Generative nucleus hi-res stock photography and images

The cotton plant in Egypt, studies in physiology and genetics . d beexamined, if only to facilitate their visualisation whenmatters relating to heredity are under discussion. The life-story of the individual begins at the moment offusion between the male and female gametes, viz., betweenthe generative nucleus of the pollen grain and the egg-cellof the ovule. The unicellular zygote thus formed developsby repeated division into an embryo enclosed in the seed-coats, and the germination of this seed is the stagecommonly regarded as beginning the life-story. Forreasons both of precision and of ulti Stock Photo

RM2AJ20JK–The cotton plant in Egypt, studies in physiology and genetics . d beexamined, if only to facilitate their visualisation whenmatters relating to heredity are under discussion. The life-story of the individual begins at the moment offusion between the male and female gametes, viz., betweenthe generative nucleus of the pollen grain and the egg-cellof the ovule. The unicellular zygote thus formed developsby repeated division into an embryo enclosed in the seed-coats, and the germination of this seed is the stagecommonly regarded as beginning the life-story. Forreasons both of precision and of ulti

Paramecium reproduction is asexual, by binary fission Stock Photo

RF2G6XNTE–Paramecium reproduction is asexual, by binary fission

. Morphology of gymnosperms. Gymnosperms; Plant morphology. 2o8 MORPHOLOGY OF GYMNOSPERMS. tubes, as in cycads, seems to function only as a haustorial system. At this stage the generative cell has the appearance of being pushed away from contact with the persistent vegetative cell, on account of the enlargement and development of vacuoles in the latter. The generative cell increases very much in size, its nucleus keeping pace with it; and these relative positions' are maintained until just before fertilization, which occurs about ten weeks later. About the middle of July the generative nucleus Stock Photo

RMPG1R7X–. Morphology of gymnosperms. Gymnosperms; Plant morphology. 2o8 MORPHOLOGY OF GYMNOSPERMS. tubes, as in cycads, seems to function only as a haustorial system. At this stage the generative cell has the appearance of being pushed away from contact with the persistent vegetative cell, on account of the enlargement and development of vacuoles in the latter. The generative cell increases very much in size, its nucleus keeping pace with it; and these relative positions' are maintained until just before fertilization, which occurs about ten weeks later. About the middle of July the generative nucleus

Paramecium cells are ovoid, elongate, foot- or cigar-shaped Stock Photo

RF2G6XNTJ–Paramecium cells are ovoid, elongate, foot- or cigar-shaped

Generative organs of thale cress (Arabidopsis thaliana) Stock Photo

RMCWEA8T–Generative organs of thale cress (Arabidopsis thaliana)

RMRDH6GW–. Morphology of gymnosperms. Gymnosperms; Plant morphology. 2o8 MORPHOLOGY OF GYMNOSPERMS. tubes, as in cycads, seems to function only as a haustorial system. At this stage the generative cell has the appearance of being pushed away from contact with the persistent vegetative cell, on account of the enlargement and development of vacuoles in the latter. The generative cell increases very much in size, its nucleus keeping pace with it; and these relative positions' are maintained until just before fertilization, which occurs about ten weeks later. About the middle of July the generative nucleus

. Botany for agricultural students . Botany. MALE GAMETOPHYTE AND FERTILIZATION 465 The pollen tube lives as a parasite on the structures through which it passes, using their tissues as food for growth and mak- ing a passageway for itself at the same time. The growth of the pollen tube is directed by the tube nucleus which maintains a position near the end of the tube. Soon after the pollen tube is well started, the generative nucleus passes from the pollen grain into the tube and later divides, forming two sperms which are carried along with the con- tents of the tube to the embryo sac. The m Stock Photo

RMPG3RY7–. Botany for agricultural students . Botany. MALE GAMETOPHYTE AND FERTILIZATION 465 The pollen tube lives as a parasite on the structures through which it passes, using their tissues as food for growth and mak- ing a passageway for itself at the same time. The growth of the pollen tube is directed by the tube nucleus which maintains a position near the end of the tube. Soon after the pollen tube is well started, the generative nucleus passes from the pollen grain into the tube and later divides, forming two sperms which are carried along with the con- tents of the tube to the embryo sac. The m

. Contributions from the Laboratory of Plant Genetics. June,1924] BRINK — PHYSIOLOGY OF POLLEN 355 vivo. In the majority of the tubes growing on the artificial medium, the nuclei migrate into the tubes in the early stages of development and there- after maintain a relation to the growing tip similar to that found in the styles of such other Liliaceae as have been examined by various workers. On the artificial cultures, moreover, division of the generative nucleus to form the two male gamete nuclei in the longer tubes has been frequently observed. The possession of these facts on nuclear behavi Stock Photo

RMREA5D7–. Contributions from the Laboratory of Plant Genetics. June,1924] BRINK — PHYSIOLOGY OF POLLEN 355 vivo. In the majority of the tubes growing on the artificial medium, the nuclei migrate into the tubes in the early stages of development and there- after maintain a relation to the growing tip similar to that found in the styles of such other Liliaceae as have been examined by various workers. On the artificial cultures, moreover, division of the generative nucleus to form the two male gamete nuclei in the longer tubes has been frequently observed. The possession of these facts on nuclear behavi

. Botany for agricultural students . Botany. Fig. 49. — Pollen grains in different stages preparatory to fertilization. A, surface view of a pollen grain; B, section through pollen grain in uni-nucleate stage; C, section through pollen grain showing the nucleus divided into the generative (g) and tube nucleus (l); D, pollen tube forming into which the two nuclei have passed; E, tube more developed and generative nucleus divided into two sperms (<;), Much enlarged. Fig. 50. — A diagram of a length- wise section through the pistil of Red Clover, showing pollen tubes trav- ersing the stigma an Stock Photo

RMPG438P–. Botany for agricultural students . Botany. Fig. 49. — Pollen grains in different stages preparatory to fertilization. A, surface view of a pollen grain; B, section through pollen grain in uni-nucleate stage; C, section through pollen grain showing the nucleus divided into the generative (g) and tube nucleus (l); D, pollen tube forming into which the two nuclei have passed; E, tube more developed and generative nucleus divided into two sperms (<;), Much enlarged. Fig. 50. — A diagram of a length- wise section through the pistil of Red Clover, showing pollen tubes trav- ersing the stigma an

. Morphology of spermatophytes. [Part I. Gymnosperms]. Gymnosperms; Plant morphology. 92 MORPHOLOGY OP SPERMATOPHYTBS covered the true functions, the more prominent nucleus of the tube cell was regarded as the generative nucleus. By this time the large tube cell has become very full of starch, and no further division occurs until the following spring, a period of about eleven months. In this con- dition also pollination occurs, and the old spore wall with its con- ...///. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability Stock Photo

RMRE2HGN–. Morphology of spermatophytes. [Part I. Gymnosperms]. Gymnosperms; Plant morphology. 92 MORPHOLOGY OP SPERMATOPHYTBS covered the true functions, the more prominent nucleus of the tube cell was regarded as the generative nucleus. By this time the large tube cell has become very full of starch, and no further division occurs until the following spring, a period of about eleven months. In this con- dition also pollination occurs, and the old spore wall with its con- ...///. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability

. Morphology of gymnosperms. Gymnosperms; Plant morphology. CONIFERALES (PINACEAE) 275. and the pollen, caught in this pollination drop, is conveyed to the nucellus (fig. 315). The pollen tube begins to grow into the nucellus as soon as the spore is deposited, and continues to develop until it is checked by cold weather. The next spring the tube begins to renew its penetration of the nucellus during April, about a year after the pollen mother cell entered upon the reduction divisions, the large tube nucleus enters the tube, and at the same time the generative cell divides into the stalk cell ( Stock Photo

RMPG2JW2–. Morphology of gymnosperms. Gymnosperms; Plant morphology. CONIFERALES (PINACEAE) 275. and the pollen, caught in this pollination drop, is conveyed to the nucellus (fig. 315). The pollen tube begins to grow into the nucellus as soon as the spore is deposited, and continues to develop until it is checked by cold weather. The next spring the tube begins to renew its penetration of the nucellus during April, about a year after the pollen mother cell entered upon the reduction divisions, the large tube nucleus enters the tube, and at the same time the generative cell divides into the stalk cell (

. Botany, with agricultural applications. Botany. MALE GAMETOPHYTE AND FERTILIZATION 465 The pollen tube lives as a parasite on the structures through which it passes, using their tissues as food for growth and mak- ing a passageway for itself at the same time. The growth of the pollen tube is directed by the tube nucleus which maintains a position near the end of the tube. Soon after the pollen tube is well started, the generative nucleus passes from the pollen grain into the tube and later divides, forming two sperms which are carried along with the con- tents of the tube to the embryo sac. Stock Photo

RMRDTG0T–. Botany, with agricultural applications. Botany. MALE GAMETOPHYTE AND FERTILIZATION 465 The pollen tube lives as a parasite on the structures through which it passes, using their tissues as food for growth and mak- ing a passageway for itself at the same time. The growth of the pollen tube is directed by the tube nucleus which maintains a position near the end of the tube. Soon after the pollen tube is well started, the generative nucleus passes from the pollen grain into the tube and later divides, forming two sperms which are carried along with the con- tents of the tube to the embryo sac.

. Morphology of gymnosperms. Gymnosperms; Plant morphology. CYCADALES 141 It is generally accepted that the cycads are wind-pollinated. Pearson (47), however, observed insects dusted with the pollen of Encephalartos villosus, and believes it is probable that they effect. Figs. 155-159.—Dioon edule'; the germination of the microspore; fig. 155, the nucleus in early prophase o£ the first mitosis, exine and inline sharply differentiated (August 14, 1905); fig. 156, the shedding stage (September 1906); fig. 157,'beginning of the pollen tube; /, tube nucleus; g, generative cell; p, prothallial cell Stock Photo

RMPG2KBC–. Morphology of gymnosperms. Gymnosperms; Plant morphology. CYCADALES 141 It is generally accepted that the cycads are wind-pollinated. Pearson (47), however, observed insects dusted with the pollen of Encephalartos villosus, and believes it is probable that they effect. Figs. 155-159.—Dioon edule'; the germination of the microspore; fig. 155, the nucleus in early prophase o£ the first mitosis, exine and inline sharply differentiated (August 14, 1905); fig. 156, the shedding stage (September 1906); fig. 157,'beginning of the pollen tube; /, tube nucleus; g, generative cell; p, prothallial cell

. Introduction to botany. Botany. POLLIXATIOX AXD FEETILIZATIOX 135 extremely slender, sticky tlareads. The mature grain contains two nuclei, a generative nucleus and a tube nucleus. Contact of the pollen grain with the moist stigmatic surface brings about osmosis, which results m distention of the pollen grain. At some point the outer coat becomes ruptured and the inner thin coat protrudes through the opening and is the beginning of the pollen tube. Then a portion of the contents of the grain passes out into the pollen tube, which is developed from the tliin inner coat of the pollen grain (fi Stock Photo

RMRE3A7H–. Introduction to botany. Botany. POLLIXATIOX AXD FEETILIZATIOX 135 extremely slender, sticky tlareads. The mature grain contains two nuclei, a generative nucleus and a tube nucleus. Contact of the pollen grain with the moist stigmatic surface brings about osmosis, which results m distention of the pollen grain. At some point the outer coat becomes ruptured and the inner thin coat protrudes through the opening and is the beginning of the pollen tube. Then a portion of the contents of the grain passes out into the pollen tube, which is developed from the tliin inner coat of the pollen grain (fi

. Lessons in botany. Botany. POLLINATION AND FERTILIZATION. 205. respond to the spermatozoids, though they are not motile. Sometimes the sperm cells are formed within the pollen grain. At other times they are only formed after the pollen grain has germinated. In fig. 184 is a germinating pollen grain of peltandra, showing three nuclei. The generative cell has di- vided to form the two sperm cells. 336. The embryo sat? is the female prothallium.—Now while the small Germinating spores , ,. (pollen grains) of pel- Spore (= the pollen gram) escapes tandra ; generative ,. r . , . , nucleus in one u Stock Photo

RMPG00J0–. Lessons in botany. Botany. POLLINATION AND FERTILIZATION. 205. respond to the spermatozoids, though they are not motile. Sometimes the sperm cells are formed within the pollen grain. At other times they are only formed after the pollen grain has germinated. In fig. 184 is a germinating pollen grain of peltandra, showing three nuclei. The generative cell has di- vided to form the two sperm cells. 336. The embryo sat? is the female prothallium.—Now while the small Germinating spores , ,. (pollen grains) of pel- Spore (= the pollen gram) escapes tandra ; generative ,. r . , . , nucleus in one u

. Botany for agricultural students. Plants. MALE GAMETOPHVTE AND FEirilLlZATlON 465 The pollen tube lives as a parasite on the structures tlu-ough which it passes, using their tissues as food for growth and mak- ing a passageway for itself at the same time. The growth of the pollen tube is directed by the tube nucleus which maintains a position near the end of the tube. Soon after the pollen tube is well started, the generative nucleus passes from the pollen grain into the tube and later divides, forming two sperms which are carried along with the con- tents of the tube to the embryo sac. The Stock Photo

RMRH8HD8–. Botany for agricultural students. Plants. MALE GAMETOPHVTE AND FEirilLlZATlON 465 The pollen tube lives as a parasite on the structures tlu-ough which it passes, using their tissues as food for growth and mak- ing a passageway for itself at the same time. The growth of the pollen tube is directed by the tube nucleus which maintains a position near the end of the tube. Soon after the pollen tube is well started, the generative nucleus passes from the pollen grain into the tube and later divides, forming two sperms which are carried along with the con- tents of the tube to the embryo sac. The

. Morphology of gymnosperms. Gymnosperms; Plant morphology. 319 320. Figs. 319-321.—Araucaria Bidwillii: fig. 319, portion of the prothallial end of the pol- len grain, showing two prothallial cells, each of which has divided, giving rise to numerous cells; the next division of the nucleus beyond the prothallial complex will give rise to the generative cell and tube nucleus; X666; fig. 320, later stage, transverse section, showing body cell in the center surroimded by nuclei which have been set free by the breaking down of the walls of the prothallial cells; X666; fig. 321, pollen tube with nu Stock Photo

RMPG2JTT–. Morphology of gymnosperms. Gymnosperms; Plant morphology. 319 320. Figs. 319-321.—Araucaria Bidwillii: fig. 319, portion of the prothallial end of the pol- len grain, showing two prothallial cells, each of which has divided, giving rise to numerous cells; the next division of the nucleus beyond the prothallial complex will give rise to the generative cell and tube nucleus; X666; fig. 320, later stage, transverse section, showing body cell in the center surroimded by nuclei which have been set free by the breaking down of the walls of the prothallial cells; X666; fig. 321, pollen tube with nu

. College botany; structure, physiology and economics of plants. Botany. PLAJSTT REPRODUCTION 95 tive nucleus. This usually occurs just before or at the time of the transfer of the pollen grain to tlie stigma. The generative nucleus divides into two sperm or male nuclei. The pollen grain produces a tube which penetrates the stigma and grows down the style. The tube nucleus enters the tube followed by the two sperm nuclei. Their further history will b© followed later (see pages 9Y and 98). The position of the ovules with reference to their form and. Fig. 70.—Types of pollen grain. attachments e Stock Photo

RMRE1NY7–. College botany; structure, physiology and economics of plants. Botany. PLAJSTT REPRODUCTION 95 tive nucleus. This usually occurs just before or at the time of the transfer of the pollen grain to tlie stigma. The generative nucleus divides into two sperm or male nuclei. The pollen grain produces a tube which penetrates the stigma and grows down the style. The tube nucleus enters the tube followed by the two sperm nuclei. Their further history will b© followed later (see pages 9Y and 98). The position of the ovules with reference to their form and. Fig. 70.—Types of pollen grain. attachments e

. Morphology of gymnosperms. Gymnosperms; Plant morphology. CONIFERALES (TAXACEAE) 341 Ginkgo, but in Phyllocladus the nucleus (or nuclei) becomes free. As a consequence, the spores on the tip of the nucellus are found to contain three or four nuclei, one or two of which are vegetative, and the body cell. In Dacrydium (136) the generative cell is cut. Figs. 392-396.—Pollen grains of several podocarps: stalk, body, and prothaUial cells evident; fig. 392, Phyllocladus alpina, showing an evanescent and a persistent prothaUial cell, also stalk, body, and tube cells; X950; after Miss Yotjng (174); Stock Photo

RMPG2JGB–. Morphology of gymnosperms. Gymnosperms; Plant morphology. CONIFERALES (TAXACEAE) 341 Ginkgo, but in Phyllocladus the nucleus (or nuclei) becomes free. As a consequence, the spores on the tip of the nucellus are found to contain three or four nuclei, one or two of which are vegetative, and the body cell. In Dacrydium (136) the generative cell is cut. Figs. 392-396.—Pollen grains of several podocarps: stalk, body, and prothaUial cells evident; fig. 392, Phyllocladus alpina, showing an evanescent and a persistent prothaUial cell, also stalk, body, and tube cells; X950; after Miss Yotjng (174);

. The plant cell, its modifications and vital processes; a manual for students. Plant physiology; Plant anatomy; Plant cells and tissues. Fig. 104.—a, Photomicrograph showing three arehegonia. h. Photomicro- graph showing to the left tlie canal of an archegoniura leading into the arohegonium proper. A pollen-tube is seen just penetrating the upper end of the embryo-sac ; the generative nucleus is to be seeS close to the upper end of the right-hand archegoniura.. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - colorati Stock Photo

RMRDYC4M–. The plant cell, its modifications and vital processes; a manual for students. Plant physiology; Plant anatomy; Plant cells and tissues. Fig. 104.—a, Photomicrograph showing three arehegonia. h. Photomicro- graph showing to the left tlie canal of an archegoniura leading into the arohegonium proper. A pollen-tube is seen just penetrating the upper end of the embryo-sac ; the generative nucleus is to be seeS close to the upper end of the right-hand archegoniura.. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - colorati

. Essentials of botany. Botany; Botany. PERTlLIZATIOlsr 165 193. Fertilization. — Fertilization in seed-plants means the union of a sperm nucleus derived from a generative P cell of a pollen graiin with an egg-cell at the apex of the embryo sac (Fig. 124). This process gives rise to a cell. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Bergen, Joseph Y. (Joseph Young), 1851-1917. Boston, Ginn Stock Photo

RMPG41TJ–. Essentials of botany. Botany; Botany. PERTlLIZATIOlsr 165 193. Fertilization. — Fertilization in seed-plants means the union of a sperm nucleus derived from a generative P cell of a pollen graiin with an egg-cell at the apex of the embryo sac (Fig. 124). This process gives rise to a cell. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Bergen, Joseph Y. (Joseph Young), 1851-1917. Boston, Ginn

RMRDCY0R–. Botany for agricultural students . Botany. MALE GAMETOPHYTE AND FERTILIZATION 465 The pollen tube lives as a parasite on the structures through which it passes, using their tissues as food for growth and mak- ing a passageway for itself at the same time. The growth of the pollen tube is directed by the tube nucleus which maintains a position near the end of the tube. Soon after the pollen tube is well started, the generative nucleus passes from the pollen grain into the tube and later divides, forming two sperms which are carried along with the con- tents of the tube to the embryo sac. The m

. Essentials of botany. Botany; Botany. Pig. 123. Germination of Pollen Grain of an Angiosperm. (Much magnified and somewhat dia^ grammatic.) Pig. 122. Pollen Grains producing ^' ™*'^« S^ain, with germination con- siderably advanced. B, tip of pollen tube at a much later stage, after the tube nucleus has disappeared: g, the generative cell beginning to enter the tube;, t, the tube nucleus; s, sperm Tubes, on Stigma of a Lily. (Much magnified.) g, pollen grains; t, pollen tubes; p, papillse of stigma; e, canal or passage running toward ovary. cells formed from the generative cell. which contain Stock Photo

RMPG41TE–. Essentials of botany. Botany; Botany. Pig. 123. Germination of Pollen Grain of an Angiosperm. (Much magnified and somewhat dia^ grammatic.) Pig. 122. Pollen Grains producing ^' ™*'^« S^ain, with germination con- siderably advanced. B, tip of pollen tube at a much later stage, after the tube nucleus has disappeared: g, the generative cell beginning to enter the tube;, t, the tube nucleus; s, sperm Tubes, on Stigma of a Lily. (Much magnified.) g, pollen grains; t, pollen tubes; p, papillse of stigma; e, canal or passage running toward ovary. cells formed from the generative cell. which contain

. The plant cell, its modifications and vital processes; a manual for students. Plant physiology; Plant anatomy; Plant cells and tissues. Fig. 105.—1. An arohegonium at the apex of the embryo-sao of Pimm, containing an oosphere which has just received a generative nucleus from the microspore (small nucleus just above the larger one of the oosphere). 2. The first two divisions at the lower pole of the oospore, subsequent to fertilisation. 3. Shows the appearance at the end of the third division. The lowest cells are the embryonal cells ; the lowest but one (6) are the cells from which the suspe Stock Photo

RMRDYC35–. The plant cell, its modifications and vital processes; a manual for students. Plant physiology; Plant anatomy; Plant cells and tissues. Fig. 105.—1. An arohegonium at the apex of the embryo-sao of Pimm, containing an oosphere which has just received a generative nucleus from the microspore (small nucleus just above the larger one of the oosphere). 2. The first two divisions at the lower pole of the oospore, subsequent to fertilisation. 3. Shows the appearance at the end of the third division. The lowest cells are the embryonal cells ; the lowest but one (6) are the cells from which the suspe

. Morphology of gymnosperms. Gymnosperms; Plant morphology. Figs. 160-165.—Cycas revoluta: fig. 160, pollen grains at shedding stage; Xsoo, fig. 161, later stage, showing prothallial cell {p) and generative cell [g), the tube nucleus not shown; X200; fig. 162, generative cell divided, giving rise to stalk and body cells; Xsoo; fig. 163, the stalk nucleus {s) being crowded out, and blepharoplasts appearing in the body cell (6); X500; fig. 164, the body cell shortly before division, showing two well-developed blepharoplasts; X 750; fig. 165, the two male cells resulting from the division of the Stock Photo

RMPG2KAR–. Morphology of gymnosperms. Gymnosperms; Plant morphology. Figs. 160-165.—Cycas revoluta: fig. 160, pollen grains at shedding stage; Xsoo, fig. 161, later stage, showing prothallial cell {p) and generative cell [g), the tube nucleus not shown; X200; fig. 162, generative cell divided, giving rise to stalk and body cells; Xsoo; fig. 163, the stalk nucleus {s) being crowded out, and blepharoplasts appearing in the body cell (6); X500; fig. 164, the body cell shortly before division, showing two well-developed blepharoplasts; X 750; fig. 165, the two male cells resulting from the division of the

. Breeding crop plants. Plant breeding. PLAXT riENETICS 19 elongates, forming a pollen tube which passes down the style. This tube grows through the tissue of the pistil and reaches the embryo sac. The generative nucleus passes into the pollen tu])e and divides, forming two nuclei which are the male gametes. The pollen tube grows through the tissues of the pistil until it reaches the embryo sac, and the tip of the tube breaks after it penetrates the wall of the embryo sac. In fertilization one of. Fig. 5.—Longitudinal section of the lower portion of the embryo sac of maize at the time of ferti Stock Photo

RMRH6W38–. Breeding crop plants. Plant breeding. PLAXT riENETICS 19 elongates, forming a pollen tube which passes down the style. This tube grows through the tissue of the pistil and reaches the embryo sac. The generative nucleus passes into the pollen tu])e and divides, forming two nuclei which are the male gametes. The pollen tube grows through the tissues of the pistil until it reaches the embryo sac, and the tip of the tube breaks after it penetrates the wall of the embryo sac. In fertilization one of. Fig. 5.—Longitudinal section of the lower portion of the embryo sac of maize at the time of ferti

. The Botanical magazine. Plants; Plants -- Japan. 46 THE BOTANICAL MAGAZINE. [Vol. XXII. No. 254. enlarges more rapidly and becomes surrounded by a denser mass of cytoplasm and forms the so-caliea body-cell, and the other, the stalk-nucleus, remains comparatively small in size and lies free in the cytoplasm of the tube. The exact moment of the division has not been determined, but it seems pro- bable that it takes place very soon after the entering of the generative nucleus into the tube. As the pollen- tube grows down- wards the body-cell and two nuclei in- crease in size, the latter being u Stock Photo

RMRHB178–. The Botanical magazine. Plants; Plants -- Japan. 46 THE BOTANICAL MAGAZINE. [Vol. XXII. No. 254. enlarges more rapidly and becomes surrounded by a denser mass of cytoplasm and forms the so-caliea body-cell, and the other, the stalk-nucleus, remains comparatively small in size and lies free in the cytoplasm of the tube. The exact moment of the division has not been determined, but it seems pro- bable that it takes place very soon after the entering of the generative nucleus into the tube. As the pollen- tube grows down- wards the body-cell and two nuclei in- crease in size, the latter being u

. Botanisk tidsskrift. Botany; Plants; Plants. — 155 — in H. umbeüatum. Such a variation in one and the same genus is very rare. In the group Pilosella the numbers 7 and 9 seem to be the basis numbers for the greater amounts. The first and second divisions proceed quite normally without the formation of such dwarfed nuclei as in H. excellens. The nucleus of the pollen cell divides in the ordinary manner into one vegetative and one generative nucleus.. The Formation of the Embryo Sac. In a preliminary note which has just lately been published (Rosenberg 25) I have shown, that in H. excellens an Stock Photo

RMRH96P5–. Botanisk tidsskrift. Botany; Plants; Plants. — 155 — in H. umbeüatum. Such a variation in one and the same genus is very rare. In the group Pilosella the numbers 7 and 9 seem to be the basis numbers for the greater amounts. The first and second divisions proceed quite normally without the formation of such dwarfed nuclei as in H. excellens. The nucleus of the pollen cell divides in the ordinary manner into one vegetative and one generative nucleus.. The Formation of the Embryo Sac. In a preliminary note which has just lately been published (Rosenberg 25) I have shown, that in H. excellens an

. Botanisk tidsskrift. Plants; Plants -- Denmark. 155 in H. umbellatum. Such a variation in one and the same genus is very rare. In the group Pilosella the numbers 7 and 9 seem to be the basis numbers for the greater amounts. The first and second divisions proceed quite normally without the formation of such dwarfed nuclei as in H. excel/ens. The nucleus of the pollen cell divides in the ordinary manner into one vegetative and one generative nucleus.. The Formation of the Embryo Sac. In a preliminary note which has just lately been published (Rosenberg 25) I have shown, that in H. excellens an Stock Photo

RMRH9MCM–. Botanisk tidsskrift. Plants; Plants -- Denmark. 155 in H. umbellatum. Such a variation in one and the same genus is very rare. In the group Pilosella the numbers 7 and 9 seem to be the basis numbers for the greater amounts. The first and second divisions proceed quite normally without the formation of such dwarfed nuclei as in H. excel/ens. The nucleus of the pollen cell divides in the ordinary manner into one vegetative and one generative nucleus.. The Formation of the Embryo Sac. In a preliminary note which has just lately been published (Rosenberg 25) I have shown, that in H. excellens an

. Advanced biology. Biology; Physiology; Reproduction. Sperm nuclei tube nucleus Production of the male gamete. Pollen is produced in the anther of the stamen. Certain cells in tjie anther go through a maturing process in which reduction division takes place. Mature pollen nuclei contain one half the number of chromosomes characteristic of the other cells of that particular plant. When A pollen grain has two nuclei, one a tube nu- cleus, the other a gener- ative nucleus. As the pollen grain forms the pollen tube, male gam- etes (the sperm nuclei) are produced from the generative nucleus.. Plea Stock Photo

RMRR26R1–. Advanced biology. Biology; Physiology; Reproduction. Sperm nuclei tube nucleus Production of the male gamete. Pollen is produced in the anther of the stamen. Certain cells in tjie anther go through a maturing process in which reduction division takes place. Mature pollen nuclei contain one half the number of chromosomes characteristic of the other cells of that particular plant. When A pollen grain has two nuclei, one a tube nu- cleus, the other a gener- ative nucleus. As the pollen grain forms the pollen tube, male gam- etes (the sperm nuclei) are produced from the generative nucleus.. Plea

$. Practical botany. Botany. 116 PEACTICAL BOTAKY Each mature grain contains a generative nucleus and a tvhe nucleus {g and t, Fig. 107, A). After the pollen grain lodges on the stigma the inner coat of the grain becomes slightly distended by osmosis, pro- duced by contact with the moist stigmatic surface. The distention of the inner coat causes it to protrude through the outer coat and it at length develops into the wall of a pollen tube (Fig. 107). This tube has the nucleus (f) at its tip and a generative cell (^) somewhere within the tube. Finally the genera- tive cell divides in- to two mal Stock Photo$

RMRE2M3A–. Practical botany. Botany. 116 PEACTICAL BOTAKY Each mature grain contains a generative nucleus and a tvhe nucleus {g and t, Fig. 107, A). After the pollen grain lodges on the stigma the inner coat of the grain becomes slightly distended by osmosis, pro- duced by contact with the moist stigmatic surface. The distention of the inner coat causes it to protrude through the outer coat and it at length develops into the wall of a pollen tube (Fig. 107). This tube has the nucleus (f) at its tip and a generative cell (^) somewhere within the tube. Finally the genera- tive cell divides in- to two mal

. Breeding crop plants. Plant breeding. Embryo sac Synergids Egg cell or female gamete^ Embryo sac Polar or endosperm nuclei Antipodal cells of nutritional value K-J Pollen grain O0-Tube / nucleus Generative nucleus Fig. 3.—Diagram to illustrate production of male and female gametes. A, In some forms as Lilium this megaspore mother cell functions directly as the embrj^o sac. Reduction division in Lilium occurs at the first nuclear division within the embrj'o sac. cell are unstained. In the soma or body of the plant the nucleus of each cell contains a definite number of chromosomes, half of wh Stock Photo

RMRH6W45–. Breeding crop plants. Plant breeding. Embryo sac Synergids Egg cell or female gamete^ Embryo sac Polar or endosperm nuclei Antipodal cells of nutritional value K-J Pollen grain O0-Tube / nucleus Generative nucleus Fig. 3.—Diagram to illustrate production of male and female gametes. A, In some forms as Lilium this megaspore mother cell functions directly as the embrj^o sac. Reduction division in Lilium occurs at the first nuclear division within the embrj'o sac. cell are unstained. In the soma or body of the plant the nucleus of each cell contains a definite number of chromosomes, half of wh

RMRDDXM4–. Botany for agricultural students . Botany. Fig. 49. — Pollen grains in different stages preparatory to fertilization. A, surface view of a pollen grain; B, section through pollen grain in uni-nucleate stage; C, section through pollen grain showing the nucleus divided into the generative (g) and tube nucleus (l); D, pollen tube forming into which the two nuclei have passed; E, tube more developed and generative nucleus divided into two sperms (<;), Much enlarged. Fig. 50. — A diagram of a length- wise section through the pistil of Red Clover, showing pollen tubes trav- ersing the stigma an

. Maize; its history, cultivation, handling, and uses, with special reference to South Africa; a text-book for farmers, students of agriculture, and teachers of nature study. Corn; Corn. EOT A NIC A L CHA RACTERS 99 smaller bodies called nuclei, one being known as the vegetative nucleus and the other as the generative nucleus. The writer has counted 636 spikelets on a tassel of sugar maize, containing in all 3,816 stamens, while the more robust "field corns" (i.e. dent and flint varieties) may carry about 7,200 stamens. The pollen grains produced in one anther CHAP. IV.. Fig. 45.—You Stock Photo

RMRE4M1X–. Maize; its history, cultivation, handling, and uses, with special reference to South Africa; a text-book for farmers, students of agriculture, and teachers of nature study. Corn; Corn. EOT A NIC A L CHA RACTERS 99 smaller bodies called nuclei, one being known as the vegetative nucleus and the other as the generative nucleus. The writer has counted 636 spikelets on a tassel of sugar maize, containing in all 3,816 stamens, while the more robust "field corns" (i.e. dent and flint varieties) may carry about 7,200 stamens. The pollen grains produced in one anther CHAP. IV.. Fig. 45.—You

. Botany for agricultural students. Plants. Fig. 49. — Pollen grains in different stages preparatory to fertilization. A, surface view of a pollen grain; B, section through pollen grain in uni-nucleate stage; C, section through pollen grain showing the nucleus divided into the generative (g) and tube nucleus (t); D, pollen tube forming into which the two nuclei have passed; E, tube more developed and generative nucleus divided into two sperms (g). Much enlarged. Fig. 50. — A diagram of a length- wise section through the pistil of Red Clover, showing pollen tubes trav- ersing the stigma and sty Stock Photo

RMRH9130–. Botany for agricultural students. Plants. Fig. 49. — Pollen grains in different stages preparatory to fertilization. A, surface view of a pollen grain; B, section through pollen grain in uni-nucleate stage; C, section through pollen grain showing the nucleus divided into the generative (g) and tube nucleus (t); D, pollen tube forming into which the two nuclei have passed; E, tube more developed and generative nucleus divided into two sperms (g). Much enlarged. Fig. 50. — A diagram of a length- wise section through the pistil of Red Clover, showing pollen tubes trav- ersing the stigma and sty

. Morphology of angiosperms (Morphology of spermatophytes. Part II). Angiosperms; Plant morphology. Fig. 58.—Development of male gametophyte iu Aselepiae. A-B, A. Corwuti; C-E, A. tuberosa. A, section of young microsporangium showing archesporial cells; B, portion of the single layer of elongated, mother-cells; C later stage showing two mother-cells, the lower one dividing and showing 10 chromosomes, the gametophyte number; 7>, second division of mother-cell, by which the row of four microspores is formed; F, microspore showing tube nucleus (t) and generative nucleus {g). A, x 200 ; B-E, x Stock Photo

RMRDYJ4J–. Morphology of angiosperms (Morphology of spermatophytes. Part II). Angiosperms; Plant morphology. Fig. 58.—Development of male gametophyte iu Aselepiae. A-B, A. Corwuti; C-E, A. tuberosa. A, section of young microsporangium showing archesporial cells; B, portion of the single layer of elongated, mother-cells; C later stage showing two mother-cells, the lower one dividing and showing 10 chromosomes, the gametophyte number; 7>, second division of mother-cell, by which the row of four microspores is formed; F, microspore showing tube nucleus (t) and generative nucleus {g). A, x 200 ; B-E, x

. Botany, with agricultural applications. Botany. Fig. 49. â Pollen grains in different stages preparatory to fertilization. A, surface view of a pollen grain; B, section through pollen grain in uni-nucleate stage; C, section through pollen grain showing the nucleus divided into the generative (g) and tube nucleus (0; D, pollen tube forming into which the two nuclei have passed; B, tube more developed and generative nucleus divided into two sperms {g). Much enlarged. Fig. 50. â A diagram of a length- wise section through the pistil of Red Clover, showing pollen tubes trav- ersing the stigma an Stock Photo

RMRDWFB7–. Botany, with agricultural applications. Botany. Fig. 49. â Pollen grains in different stages preparatory to fertilization. A, surface view of a pollen grain; B, section through pollen grain in uni-nucleate stage; C, section through pollen grain showing the nucleus divided into the generative (g) and tube nucleus (0; D, pollen tube forming into which the two nuclei have passed; B, tube more developed and generative nucleus divided into two sperms {g). Much enlarged. Fig. 50. â A diagram of a length- wise section through the pistil of Red Clover, showing pollen tubes trav- ersing the stigma an

Elementary botany . romosomes. 344 MORPHOLOG Y. When fertilization takes place the number of chromosomesis doubled in the embryo.—In the spermatozoid of osmundathen, as well as in the egg, since these are developed on the game-tophyte, there are twelve chromosomes each. The same is truein the sperm-cell (generative cell) of lilium, and also in the egg-cell. When these nuclei unite, as they do in fertilization, thepaternal nucleus with the maternal nucleus, the number of chro-mosomes in the fertilized egg, if we take lilium as an example,is twenty-four instead of twelve; the number is doubled. Stock Photo

RM2AJBAGY–Elementary botany . romosomes. 344 MORPHOLOG Y. When fertilization takes place the number of chromosomesis doubled in the embryo.—In the spermatozoid of osmundathen, as well as in the egg, since these are developed on the game-tophyte, there are twelve chromosomes each. The same is truein the sperm-cell (generative cell) of lilium, and also in the egg-cell. When these nuclei unite, as they do in fertilization, thepaternal nucleus with the maternal nucleus, the number of chro-mosomes in the fertilized egg, if we take lilium as an example,is twenty-four instead of twelve; the number is doubled.

Quain's elements of anatomy . oves again towards the centre, thereto await the advent of the fertilizing agent. Since it is now somewhat differentfrom an ordinary nucleus in its incapability to initiate the division of the cellwithout the access of a fertilizing agent, as well as in structure, nonucleoijlasmic network being visible, it is no longer termed the nucleus, butthe, femalepro-nncleus (fig. 15, 4, Bf.jm). Arrived at the condition above described, the ovum seems incapable of under-going fiuther change until it has received and blended with a portion of oneof the male generative cells. Stock Photo

RM2AWN265–Quain's elements of anatomy . oves again towards the centre, thereto await the advent of the fertilizing agent. Since it is now somewhat differentfrom an ordinary nucleus in its incapability to initiate the division of the cellwithout the access of a fertilizing agent, as well as in structure, nonucleoijlasmic network being visible, it is no longer termed the nucleus, butthe, femalepro-nncleus (fig. 15, 4, Bf.jm). Arrived at the condition above described, the ovum seems incapable of under-going fiuther change until it has received and blended with a portion of oneof the male generative cells.

Elementary botany . is the vegetative cell of the prothallium, while the smaller one, since it later forms the sperm cells, is the generative cell. This generative cell then corresponds to the central cell of the antheridium, and the vegetative cell perhaps corresponds to a wall F- cell of the antheridium. If this is so, then the Germinating spores male prothallium of angiosperms has become (P°J]en grams) of pel-r & r tandra; generative reduced to a very simple antheridium. The nucleus in one undi-r ., ,, , , , r ,.,. ,. vided, in other divided farther growth takes place alter fertilization, Stock Photo

RM2AJBJX5–Elementary botany . is the vegetative cell of the prothallium, while the smaller one, since it later forms the sperm cells, is the generative cell. This generative cell then corresponds to the central cell of the antheridium, and the vegetative cell perhaps corresponds to a wall F- cell of the antheridium. If this is so, then the Germinating spores male prothallium of angiosperms has become (P°J]en grams) of pel-r & r tandra; generative reduced to a very simple antheridium. The nucleus in one undi-r ., ,, , , , r ,.,. ,. vided, in other divided farther growth takes place alter fertilization,

Elementary botany . 359. At the sametime the two cells which were formed inthe pollen grain (antheridium) from thecentral cell move down into the tube. Oneof these is the generative cell, or bodycell, and the other is called the stalk cell,though it is more properly a sterile half ofthe central cell. The nucleus of the gener-ative cell, about the time the archegoniumis mature, divides to form two nuclei,which are the sperm nuclei, and the onein advance is the larger, though it is muchsmaller than the egg nucleus. 625. Fertilization.—Very soon after thearchegonia are mature (early in June in th Stock Photo

RM2AJC26Y–Elementary botany . 359. At the sametime the two cells which were formed inthe pollen grain (antheridium) from thecentral cell move down into the tube. Oneof these is the generative cell, or bodycell, and the other is called the stalk cell,though it is more properly a sterile half ofthe central cell. The nucleus of the gener-ative cell, about the time the archegoniumis mature, divides to form two nuclei,which are the sperm nuclei, and the onein advance is the larger, though it is muchsmaller than the egg nucleus. 625. Fertilization.—Very soon after thearchegonia are mature (early in June in th

. Elementary botany. Botany. 344 MORPHOLOGY. When fertilization takes place the number of chromosomes is doubled in the embryo.—In the spemiatozoid of osmunda then, as well as in the egg, since these are developed on the game- tophyte, there are twelve chromosomes each. The same is true in the sperm-cell (generative cell) of lilium, and also in the egg- cell. When these nuclei unite, as they do in fertilization, the paternal nucleus with the maternal nucleus, the number of chro- mosomes in the fertilized egg, if we take lilium as an example, is twenty-four instead of twelve; the number is doub Stock Photo

RMRE3BHH–. Elementary botany. Botany. 344 MORPHOLOGY. When fertilization takes place the number of chromosomes is doubled in the embryo.—In the spemiatozoid of osmunda then, as well as in the egg, since these are developed on the game- tophyte, there are twelve chromosomes each. The same is true in the sperm-cell (generative cell) of lilium, and also in the egg- cell. When these nuclei unite, as they do in fertilization, the paternal nucleus with the maternal nucleus, the number of chro- mosomes in the fertilized egg, if we take lilium as an example, is twenty-four instead of twelve; the number is doub

. Elementary botany. Botany. CAMETOPHYTE AND SFOJWPHYTE. 243 When fertilization takes place the number of chromosomes is doubled in the embryo.—In the spermatozoid of osmunda then, as well as in the egg, since these are developed on the game- tophyte, there are twelve chromosomes each. The same is true in the sperm-cell (generative cell) of lilium, and also in the egg- cell. When these nuclei unite, as they do in fertilization, the paternal nucleus with the maternal nucleus, the number of chro- mosomes in the fertilized egg, if we take lilium as an example, is twenty-four instead of twelve; th Stock Photo

RMRD462E–. Elementary botany. Botany. CAMETOPHYTE AND SFOJWPHYTE. 243 When fertilization takes place the number of chromosomes is doubled in the embryo.—In the spermatozoid of osmunda then, as well as in the egg, since these are developed on the game- tophyte, there are twelve chromosomes each. The same is true in the sperm-cell (generative cell) of lilium, and also in the egg- cell. When these nuclei unite, as they do in fertilization, the paternal nucleus with the maternal nucleus, the number of chro- mosomes in the fertilized egg, if we take lilium as an example, is twenty-four instead of twelve; th

. A manual of elementary zoology . Zoology. 148 MANUAL OF ELEMENTARY ZOOLOGY body is known as the kinetonucleus, and has been supposed to have some function in connection with movement, while the nucleus proper, known as the trophonucleus, regulates the other functions of the body. The existence of two nuclei in the body of a protozoon is known as binuclearity. It will be recalled that a kind of binuclearity, in which the nuclei are not trophic and kinetic but somatic and generative, occurs in the Ciliata. Another kind, in which, so far as is known, there is no difference of function between t Stock Photo

RMRDHRN2–. A manual of elementary zoology . Zoology. 148 MANUAL OF ELEMENTARY ZOOLOGY body is known as the kinetonucleus, and has been supposed to have some function in connection with movement, while the nucleus proper, known as the trophonucleus, regulates the other functions of the body. The existence of two nuclei in the body of a protozoon is known as binuclearity. It will be recalled that a kind of binuclearity, in which the nuclei are not trophic and kinetic but somatic and generative, occurs in the Ciliata. Another kind, in which, so far as is known, there is no difference of function between t

. Elementary botany. Botany. GAMETOPHYTE AND SPOPOPHYTE. 243 When fertilization takes place the number of chromosomes is doubled in the embryo.—In the spermatozoid of osmunda then, as well as in the egg, since these are developed on the game- tophyte, there are twelve chromosomes each. The same is true in the sperm-cell (generative cell) of lilium, and also in the egg- cell. When these nuclei unite, as they do in fertilization, the paternal nucleus with the maternal nucleus, the number of chro- mosomes in the fertilized egg, if we take lilium as an example, is twenty-four instead of twelve; th Stock Photo

RMRDWETE–. Elementary botany. Botany. GAMETOPHYTE AND SPOPOPHYTE. 243 When fertilization takes place the number of chromosomes is doubled in the embryo.—In the spermatozoid of osmunda then, as well as in the egg, since these are developed on the game- tophyte, there are twelve chromosomes each. The same is true in the sperm-cell (generative cell) of lilium, and also in the egg- cell. When these nuclei unite, as they do in fertilization, the paternal nucleus with the maternal nucleus, the number of chro- mosomes in the fertilized egg, if we take lilium as an example, is twenty-four instead of twelve; th

RMRDH67D–. Morphology of gymnosperms. Gymnosperms; Plant morphology. CONIFERALES (PINACEAE) 275. and the pollen, caught in this pollination drop, is conveyed to the nucellus (fig. 315). The pollen tube begins to grow into the nucellus as soon as the spore is deposited, and continues to develop until it is checked by cold weather. The next spring the tube begins to renew its penetration of the nucellus during April, about a year after the pollen mother cell entered upon the reduction divisions, the large tube nucleus enters the tube, and at the same time the generative cell divides into the stalk cell (

. A textbook of botany for colleges and universities ... Botany. SPERMATOPHYTES 217. Fig. 4S0. — Male gametophyte of Dacrydium (one of the podo- carps) at shedding stage of pollen, showing foiir vegetative cells, stalk and body cells (formed by the generative cell), and the tube nucleus. — After Miss Young. there is much nucellar tissue to be traversed before the female gameto- phyte with its archegonia is reached. For the first time, the pollen tube acts as a carrier of the male cells, the body cell, which is to divide, entering the tube and remaining near its tip as it ad- vances through the Stock Photo

RMRDYEW9–. A textbook of botany for colleges and universities ... Botany. SPERMATOPHYTES 217. Fig. 4S0. — Male gametophyte of Dacrydium (one of the podo- carps) at shedding stage of pollen, showing foiir vegetative cells, stalk and body cells (formed by the generative cell), and the tube nucleus. — After Miss Young. there is much nucellar tissue to be traversed before the female gameto- phyte with its archegonia is reached. For the first time, the pollen tube acts as a carrier of the male cells, the body cell, which is to divide, entering the tube and remaining near its tip as it ad- vances through the

. The plant cell, its modifications and vital processes; a manual for students. Plant physiology; Plant anatomy; Plant cells and tissues. 126 THE PLANT CELL.. Pig. 95.—The Completely JLvtuked Embryo-sac or Lillum.—It shows at the upper end the synergidte, one of the generative nuclei, and the egg-cell nucleus, and, at the lower end, the large spheroidal definitive nucleus and three antipodal cells.. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resem Stock Photo

RMRDYC8C–. The plant cell, its modifications and vital processes; a manual for students. Plant physiology; Plant anatomy; Plant cells and tissues. 126 THE PLANT CELL.. Pig. 95.—The Completely JLvtuked Embryo-sac or Lillum.—It shows at the upper end the synergidte, one of the generative nuclei, and the egg-cell nucleus, and, at the lower end, the large spheroidal definitive nucleus and three antipodal cells.. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resem

. Carnegie Institution of Washington publication. GYMNOSPERMS. '53 About the first of April the blepliaroplasts have reached nearly one- half the size they finally attain. They are more or less vacuolate, and the kinoplasmic radiations, which have become more abundant, extend in many instances quite to the plasma membrane of the cell. After further growth the generative cell divides into the two cells which develop into the two spermatozoids (Fig. 61, B, and Fig. 62). The blepharoplasts take no part in the division of the nucleus. Al- though their kinoplasmic radiations become fewer, they do n Stock Photo

RMRFWBDC–. Carnegie Institution of Washington publication. GYMNOSPERMS. '53 About the first of April the blepliaroplasts have reached nearly one- half the size they finally attain. They are more or less vacuolate, and the kinoplasmic radiations, which have become more abundant, extend in many instances quite to the plasma membrane of the cell. After further growth the generative cell divides into the two cells which develop into the two spermatozoids (Fig. 61, B, and Fig. 62). The blepharoplasts take no part in the division of the nucleus. Al- though their kinoplasmic radiations become fewer, they do n

. A manual of Indian botany. Botany. FERTILIZATION 137 tube then enters into the embryo-sac and emits one of the generative cells, the other generating cell and the vegetative cell having been disorganized in the meantime. The generative cell, guided by the syner- gidae, comes into contact with the oosphere and com- pletely fuses with it, nucleus with nucleus, and proto- plasm with protoplasm, giving rise to a single cell known as oospore. This process of the formation of the oospore by the union of the male and the female element is known as FERTILIZATION. After fertilization the oospore se- Stock Photo

RMRE1R5B–. A manual of Indian botany. Botany. FERTILIZATION 137 tube then enters into the embryo-sac and emits one of the generative cells, the other generating cell and the vegetative cell having been disorganized in the meantime. The generative cell, guided by the syner- gidae, comes into contact with the oosphere and com- pletely fuses with it, nucleus with nucleus, and proto- plasm with protoplasm, giving rise to a single cell known as oospore. This process of the formation of the oospore by the union of the male and the female element is known as FERTILIZATION. After fertilization the oospore se-

. A textbook of botany for colleges and universities ... Botany. Fig. 4S0. — Male gametophyte of Dacrydium (one of the podo- carps) at shedding stage of pollen, showing foiir vegetative cells, stalk and body cells (formed by the generative cell), and the tube nucleus. — After Miss Young. there is much nucellar tissue to be traversed before the female gameto- phyte with its archegonia is reached. For the first time, the pollen tube acts as a carrier of the male cells, the body cell, which is to divide, entering the tube and remaining near its tip as it ad- vances through the tip of the nucellus Stock Photo

RMRDYEW6–. A textbook of botany for colleges and universities ... Botany. Fig. 4S0. — Male gametophyte of Dacrydium (one of the podo- carps) at shedding stage of pollen, showing foiir vegetative cells, stalk and body cells (formed by the generative cell), and the tube nucleus. — After Miss Young. there is much nucellar tissue to be traversed before the female gameto- phyte with its archegonia is reached. For the first time, the pollen tube acts as a carrier of the male cells, the body cell, which is to divide, entering the tube and remaining near its tip as it ad- vances through the tip of the nucellus

. Elementary botany. Botany. GAMErOPHYTE AXD SPOROPBYTE. 243 â When fertilization takes place the number of chromosomes is doubled in the embryo.âIn the spermatozoid of osmunda then, as well as in the egg, since these are developed on the game- tophyte, there are twelve chromosomes each. The same is true in the sperm-cell (generative cell) oi lilium, and also in the egg- cell. When these nuclei unite, as they do in fertilization, the paternal nucleus with the maternal nucleus, the number of chro- mosomes in the fertilized egg, if we take lilium as an example, is twenty-four instead of twelve; Stock Photo

RMRE1P0G–. Elementary botany. Botany. GAMErOPHYTE AXD SPOROPBYTE. 243 â When fertilization takes place the number of chromosomes is doubled in the embryo.âIn the spermatozoid of osmunda then, as well as in the egg, since these are developed on the game- tophyte, there are twelve chromosomes each. The same is true in the sperm-cell (generative cell) oi lilium, and also in the egg- cell. When these nuclei unite, as they do in fertilization, the paternal nucleus with the maternal nucleus, the number of chro- mosomes in the fertilized egg, if we take lilium as an example, is twenty-four instead of twelve;

. A textbook of botany for colleges and universities ... Botany. 200 MORPHOLOGY The subsequent development of the gametophyte occurs after the pollen grain has reached the pollen chamber. In this position the tube begins to develop and to penetrate the tissue of the nucellus, the tube nucleus passing into it. Then the generative cell, remaining within the. Figs. 457, 458. — Development of the embryo of Zantia: 457, the stage of free nuclear division; 458, tissue-formation at base of egg, with numerous free nuclei remain- ing in the general cytoplasm. — After Coulter and Chamberlain. grain, div Stock Photo

RMRDYF04–. A textbook of botany for colleges and universities ... Botany. 200 MORPHOLOGY The subsequent development of the gametophyte occurs after the pollen grain has reached the pollen chamber. In this position the tube begins to develop and to penetrate the tissue of the nucellus, the tube nucleus passing into it. Then the generative cell, remaining within the. Figs. 457, 458. — Development of the embryo of Zantia: 457, the stage of free nuclear division; 458, tissue-formation at base of egg, with numerous free nuclei remain- ing in the general cytoplasm. — After Coulter and Chamberlain. grain, div

RMRDH6P1–. Morphology of gymnosperms. Gymnosperms; Plant morphology. CYCADALES 141 It is generally accepted that the cycads are wind-pollinated. Pearson (47), however, observed insects dusted with the pollen of Encephalartos villosus, and believes it is probable that they effect. Figs. 155-159.—Dioon edule'; the germination of the microspore; fig. 155, the nucleus in early prophase o£ the first mitosis, exine and inline sharply differentiated (August 14, 1905); fig. 156, the shedding stage (September 1906); fig. 157,'beginning of the pollen tube; /, tube nucleus; g, generative cell; p, prothallial cell

. Botany of the living plant. Botany. 312 BOTANY OF THE LIVING PLANT the apex of the prothallus (Fig. 254, C). Meanwhile its generative cell has divided to form a stalk-cell and a body-cell. The former breaks away from its attachment, and the contents of the grain enter the tube. The body-cell divides during transit to form the two male gametes. Thus provided, the tube enters the neck of an archegonium, and the gametes are transferred into the ovum. The nucleus of one of the gametes fuses with the nucleus of the ovum. The result of the fusion. Fig. 254- Picea vulgaris. A = longitudinal section Stock Photo

RMRH8W9D–. Botany of the living plant. Botany. 312 BOTANY OF THE LIVING PLANT the apex of the prothallus (Fig. 254, C). Meanwhile its generative cell has divided to form a stalk-cell and a body-cell. The former breaks away from its attachment, and the contents of the grain enter the tube. The body-cell divides during transit to form the two male gametes. Thus provided, the tube enters the neck of an archegonium, and the gametes are transferred into the ovum. The nucleus of one of the gametes fuses with the nucleus of the ovum. The result of the fusion. Fig. 254- Picea vulgaris. A = longitudinal section

. Elements of botany. Botany. FERTILIZATION 165 193. Fertilization.— Fertilization in seed-plants means the union of a speini nucleus deiived from a generative p cell of a pollen grain with an egg-cell at the apex of the embryo sac (Fig- 124). This process gives rise to a cell. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Bergen, Joseph Y. (Joseph Young), 1851-1917. Boston, Ginn Stock Photo

RMRE2JNW–. Elements of botany. Botany. FERTILIZATION 165 193. Fertilization.— Fertilization in seed-plants means the union of a speini nucleus deiived from a generative p cell of a pollen grain with an egg-cell at the apex of the embryo sac (Fig- 124). This process gives rise to a cell. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Bergen, Joseph Y. (Joseph Young), 1851-1917. Boston, Ginn

RMRDY7EF–. Botany of the living plant. Botany. 312 BOTANY OF THE LIVING PLANT the apex of the prothallus (Fig. 254, C). Meanwhile its generative cell has divided to form a stalk-cell and a body-cell. The former breaks away from its attachment, and the contents of the grain enter the tube. The body-cell divides during transit to form the tu'o male gametes. Thus provided, the tube enters the neck of an archegonium, and the gametes are transferred into the ovum. The nucleus of one of the gametes fuses with the nucleus of the ovum. The result of the fusion. Fig. :;.s4. Pic^a vulgaris. A âlongitudinal secti

. A textbook of botany for colleges and universities ... Botany. SPERJMATOPHYTES 211 ing), a generative cell, and a tube nucleus. This is the shedding stage, and the subsequent de'elopment occurs in the pollen chamber, after the pollen tube has begun to develop. In that position the nucleus of the generative cell divides, but no wall is formed, the stalk nucleus being thrust out to one side of the general cytoplasm, which organizes the body cell in connection with the other nucleus. The events that follow are exactly as in the cycads: two blepharoplasts appearing in the body cell; the body ce Stock Photo

RMRDYEX8–. A textbook of botany for colleges and universities ... Botany. SPERJMATOPHYTES 211 ing), a generative cell, and a tube nucleus. This is the shedding stage, and the subsequent de'elopment occurs in the pollen chamber, after the pollen tube has begun to develop. In that position the nucleus of the generative cell divides, but no wall is formed, the stalk nucleus being thrust out to one side of the general cytoplasm, which organizes the body cell in connection with the other nucleus. The events that follow are exactly as in the cycads: two blepharoplasts appearing in the body cell; the body ce

RMRDH676–. Morphology of gymnosperms. Gymnosperms; Plant morphology. 319 320. Figs. 319-321.—Araucaria Bidwillii: fig. 319, portion of the prothallial end of the pol- len grain, showing two prothallial cells, each of which has divided, giving rise to numerous cells; the next division of the nucleus beyond the prothallial complex will give rise to the generative cell and tube nucleus; X666; fig. 320, later stage, transverse section, showing body cell in the center surroimded by nuclei which have been set free by the breaking down of the walls of the prothallial cells; X666; fig. 321, pollen tube with nu

. Practical text-book of plant physiology. Plant physiology. PURPOSE OF MULTIPLICATION OF CELLS 277 the original capacity of division and thus constitute generative layers, cambium, or phellogen, or growing regions. The increase in amount of living material of the cells formed by the generative layers, and the consequent increase in volume of these cells, accompanied by more or less morphological differ-. Fig. 131. Changes in nucleus during mitotic division. A, earliest observable stage, showing a coarsely granular thread of filament. B, a later stage in which the thread is arranged in paralle Stock Photo

RMRE3EAB–. Practical text-book of plant physiology. Plant physiology. PURPOSE OF MULTIPLICATION OF CELLS 277 the original capacity of division and thus constitute generative layers, cambium, or phellogen, or growing regions. The increase in amount of living material of the cells formed by the generative layers, and the consequent increase in volume of these cells, accompanied by more or less morphological differ-. Fig. 131. Changes in nucleus during mitotic division. A, earliest observable stage, showing a coarsely granular thread of filament. B, a later stage in which the thread is arranged in paralle

. Botany for high schools. Botany. Fig. 375- Nearly mature pollen grain of tril- lium. The smaller cell is the genera- tive cell. which floats in the tube cell but at first is s:parated by a thin arched cell wall (fig. 375). This is the generative cell or body cell, and was formed on germination of the young microspore by the division of the single nucleus of the microspore before the pollen grain was ripe. After the pollen grain has reached the stigma of the pistil (see Pollination, Chapter XVIII) it germi- nates, producing a tube 'which travels down the style (or in the stylar canal in some Stock Photo

RMRH8H85–. Botany for high schools. Botany. Fig. 375- Nearly mature pollen grain of tril- lium. The smaller cell is the genera- tive cell. which floats in the tube cell but at first is s:parated by a thin arched cell wall (fig. 375). This is the generative cell or body cell, and was formed on germination of the young microspore by the division of the single nucleus of the microspore before the pollen grain was ripe. After the pollen grain has reached the stigma of the pistil (see Pollination, Chapter XVIII) it germi- nates, producing a tube 'which travels down the style (or in the stylar canal in some

. Carnegie Institution of Washington publication. '52 ARCHEGOX1ATES. the nucleus, but, in a number of cases in this stage and in a still later stage, they have been found nearer together, frequently less than 45° apart." The first indication of a differentiation in the blepharoplast as it increases in size is seen in the formation of an outer wall or membrane. The generative cell, which has remained nearly spherical, increases in. B FIG. 61.—-Prothailiura and a dividing generative cell of Za»tta.—(After Webber.) A, prothallium in which generative cell has become large and elongated ; the Stock Photo

RMRFWBDK–. Carnegie Institution of Washington publication. '52 ARCHEGOX1ATES. the nucleus, but, in a number of cases in this stage and in a still later stage, they have been found nearer together, frequently less than 45° apart." The first indication of a differentiation in the blepharoplast as it increases in size is seen in the formation of an outer wall or membrane. The generative cell, which has remained nearly spherical, increases in. B FIG. 61.—-Prothailiura and a dividing generative cell of Za»tta.—(After Webber.) A, prothallium in which generative cell has become large and elongated ; the

. Botany for high schools. Botany. ANGIOSPERMS 381. Fig. 375- Nearly mature pollen grain of tril- lium. The smaller cell is the genera- tive cell. which floats in the tube cell but at first is s:parated by a thin arched cell wall (fig. 375). This is the generative cell or body cell, and was formed on germination of the young microspore by the division of the single nucleus of the microspore before the pollen grain was ripe. After the pollen grain has reached the stigma of the pistil (see Pollination, Chapter XVIII) it germi- nates, producing a tube 'which travels down the style (or in the styl Stock Photo

RMRH8H8G–. Botany for high schools. Botany. ANGIOSPERMS 381. Fig. 375- Nearly mature pollen grain of tril- lium. The smaller cell is the genera- tive cell. which floats in the tube cell but at first is s:parated by a thin arched cell wall (fig. 375). This is the generative cell or body cell, and was formed on germination of the young microspore by the division of the single nucleus of the microspore before the pollen grain was ripe. After the pollen grain has reached the stigma of the pistil (see Pollination, Chapter XVIII) it germi- nates, producing a tube 'which travels down the style (or in the styl

. Essentials of botany. Botany; Botany. FERTILIZATION 165 193. Fertilization.— Fertilization in seed-plants means the union of a sperm nucleus derived from a generative p cell of a pollen grain with an egg-cell at the apex of the embryo sac (Fig. 124). This process gives rise to a cell. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Bergen, Joseph Y. (Joseph Young), 1851-1917. Boston, Ginn Stock Photo

RMRDWG4T–. Essentials of botany. Botany; Botany. FERTILIZATION 165 193. Fertilization.— Fertilization in seed-plants means the union of a sperm nucleus derived from a generative p cell of a pollen grain with an egg-cell at the apex of the embryo sac (Fig. 124). This process gives rise to a cell. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Bergen, Joseph Y. (Joseph Young), 1851-1917. Boston, Ginn

. Carnegie Institution of Washington publication. . FIG. 63.—Further development of blepharoplast.—(After Webber). A, two attached spermatozoid mother-cells (spermatids) resulting from division of generative cell; the band of blepharoplast is being formed by fusion of granules. B, fusion of granules to form the band. C, formation of ciliferous band by fusion of granules, more highly magnified. ment of the band, which is to bear the cilia, begins. It appears first as a short, delicate, and deeply staining line extending from the mass of granules toward the nucleus (Fig. 63, A). A little later a Stock Photo

RMRFWBCW–. Carnegie Institution of Washington publication. . FIG. 63.—Further development of blepharoplast.—(After Webber). A, two attached spermatozoid mother-cells (spermatids) resulting from division of generative cell; the band of blepharoplast is being formed by fusion of granules. B, fusion of granules to form the band. C, formation of ciliferous band by fusion of granules, more highly magnified. ment of the band, which is to bear the cilia, begins. It appears first as a short, delicate, and deeply staining line extending from the mass of granules toward the nucleus (Fig. 63, A). A little later a

. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. 102 CALIFORNIA FISH AND GAME. FIGURE 4. Generative cell with microtuble bundle [t] adjacent to the nucleus [n]. Bar = 1 ja. No pathogenic bacteria were isolated from spleens or kidneys of affected fish, and insignificant numbers of bacteria were observed on the gills in wet mounts. Trichodina, Trichophrya and Costia were occasionally seen in low numbers on some fish and they were often absent in fish with severe HGD from the same outb Stock Photo

RMRG3N93–. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. 102 CALIFORNIA FISH AND GAME. FIGURE 4. Generative cell with microtuble bundle [t] adjacent to the nucleus [n]. Bar = 1 ja. No pathogenic bacteria were isolated from spleens or kidneys of affected fish, and insignificant numbers of bacteria were observed on the gills in wet mounts. Trichodina, Trichophrya and Costia were occasionally seen in low numbers on some fish and they were often absent in fish with severe HGD from the same outb

. Carnegie Institution of Washington publication. 146 ARCHEGONIATES. from the generative cell. To this phase of development Ikeno has applied the term spermatogenesis. As soon as all the structures mentioned accumulate in the proximal end of the tube, all save the generative cell begin to disorganize and finally disappear. What this disorganization signifies, Ikeno remarks, ••*&?• -•-'. ' • ' • '•• • t-r-J-I-SS ' :. D FIG. 58.—Division of generative cell and further development of blepharoplasts in Cycas revoluta.—(After Ikeno.) A, generative cell with nucleus in early prophase oi division Stock Photo

RMRFWBEK–. Carnegie Institution of Washington publication. 146 ARCHEGONIATES. from the generative cell. To this phase of development Ikeno has applied the term spermatogenesis. As soon as all the structures mentioned accumulate in the proximal end of the tube, all save the generative cell begin to disorganize and finally disappear. What this disorganization signifies, Ikeno remarks, ••*&?• -•-'. ' • ' • '•• • t-r-J-I-SS ' :. D FIG. 58.—Division of generative cell and further development of blepharoplasts in Cycas revoluta.—(After Ikeno.) A, generative cell with nucleus in early prophase oi division

RMRDHG54–. Essentials of botany. Botany; Botany. PERTlLIZATIOlsr 165 193. Fertilization. — Fertilization in seed-plants means the union of a sperm nucleus derived from a generative P cell of a pollen graiin with an egg-cell at the apex of the embryo sac (Fig. 124). This process gives rise to a cell. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Bergen, Joseph Y. (Joseph Young), 1851-1917. Boston, Ginn

. A textbook of botany for colleges and universities ... Botany. Fig. 44S. — Diagram of embryo sac (containing fe- male gametophyte) of Dioon, showing two archegonia and the archegonial chamber.— After Chamberlain.. Figs. 449-456. — Male gametophyte of Cycas revoluta: 449, shedding stage of micro- spore (pollen grain), showing persistent vegetative cell, generative cell, and tube cell; 450, later stage (after shedding), showing rounded-off vegetative and generative cells (tube nucleus has passed into the pollen tube); 451, division of nucleus of generative cell into nuclei of stalk and body ce Stock Photo

RMRDYF0J–. A textbook of botany for colleges and universities ... Botany. Fig. 44S. — Diagram of embryo sac (containing fe- male gametophyte) of Dioon, showing two archegonia and the archegonial chamber.— After Chamberlain.. Figs. 449-456. — Male gametophyte of Cycas revoluta: 449, shedding stage of micro- spore (pollen grain), showing persistent vegetative cell, generative cell, and tube cell; 450, later stage (after shedding), showing rounded-off vegetative and generative cells (tube nucleus has passed into the pollen tube); 451, division of nucleus of generative cell into nuclei of stalk and body ce

RMRDDA06–. Lessons in botany. Botany. POLLINATION AND FERTILIZATION. 205. respond to the spermatozoids, though they are not motile. Sometimes the sperm cells are formed within the pollen grain. At other times they are only formed after the pollen grain has germinated. In fig. 184 is a germinating pollen grain of peltandra, showing three nuclei. The generative cell has di- vided to form the two sperm cells. 336. The embryo sat? is the female prothallium.—Now while the small Germinating spores , ,. (pollen grains) of pel- Spore (= the pollen gram) escapes tandra ; generative ,. r . , . , nucleus in one u

. Botany; principles and problems. Botany. REPRODUCTION 197 mass of cytoplasm of its own, sometimes with a separate wall, and is known as the generative cell. Shortly after the pollen has reached the stigma the thick wall of the pollen grain bursts at one point and out of the grain proceeds a thin-walled pollen-tube. Near the tip of this moves the tube-nucleus, followed by the generative cell (Fig. 111). This tube bores through the tissues. Fiu. 111.—Germinating pollen of squash. The pollen grain has burst and a pollen tube is starting down through the style. Near the end of the tube is the tu Stock Photo

RMRH8G7W–. Botany; principles and problems. Botany. REPRODUCTION 197 mass of cytoplasm of its own, sometimes with a separate wall, and is known as the generative cell. Shortly after the pollen has reached the stigma the thick wall of the pollen grain bursts at one point and out of the grain proceeds a thin-walled pollen-tube. Near the tip of this moves the tube-nucleus, followed by the generative cell (Fig. 111). This tube bores through the tissues. Fiu. 111.—Germinating pollen of squash. The pollen grain has burst and a pollen tube is starting down through the style. Near the end of the tube is the tu

RMRDH61J–. Morphology of gymnosperms. Gymnosperms; Plant morphology. CONIFERALES (TAXACEAE) 341 Ginkgo, but in Phyllocladus the nucleus (or nuclei) becomes free. As a consequence, the spores on the tip of the nucellus are found to contain three or four nuclei, one or two of which are vegetative, and the body cell. In Dacrydium (136) the generative cell is cut. Figs. 392-396.—Pollen grains of several podocarps: stalk, body, and prothaUial cells evident; fig. 392, Phyllocladus alpina, showing an evanescent and a persistent prothaUial cell, also stalk, body, and tube cells; X950; after Miss Yotjng (174);

. The cell in development and inheritance. Cells. FERTILIZATION IN PLANTS 219 egg (Fig. 108); and the earlier observers of the angiosperms, includ- ing Strasburger ('84, '88) and Guignard ('91, i), likewise found that only one of the generative nuclei entered the embryo-sac. Guignard //. Fig. 107.— Fertilization in the lily. D from Mottier, the others from Guignard.] A. Embryo-sac, ready for fertilization. B. Both generative nuclei have entered the embrvo- sac; one is approaching the egg-nucleus, the other uniting with the upper polar nucleus. C. Union of the germ-nuclei; below, union of the Stock Photo

RMRJBC0T–. The cell in development and inheritance. Cells. FERTILIZATION IN PLANTS 219 egg (Fig. 108); and the earlier observers of the angiosperms, includ- ing Strasburger ('84, '88) and Guignard ('91, i), likewise found that only one of the generative nuclei entered the embryo-sac. Guignard //. Fig. 107.— Fertilization in the lily. D from Mottier, the others from Guignard.] A. Embryo-sac, ready for fertilization. B. Both generative nuclei have entered the embrvo- sac; one is approaching the egg-nucleus, the other uniting with the upper polar nucleus. C. Union of the germ-nuclei; below, union of the

RMRJBCYD–. The cell in development and inheritance. Cells. FERTILIZATION IN PLANTS 219 egg (Fig. 108); and the earlier observers of the angiosperms, includ- ing Strasburger ('84, '88) and Guignard ('91, i), likewise found that only one of the generative nuclei entered the embryo-sac. Guio-nard // •. Fig. 107. — Fertilization in the lily. D from Mottier, the others from Guignard.] A. Embryo-sac, ready for fertilization. B. Both generative nuclei have entered the embryo- sac ; one is approaching the egg-nucleus, the other uniting with the upper polar nucleus. C. Union of the germ-nuclei; below, union of

. Textbook of botany. Botany. Fig. 70. — A cluster o£ staminate cones of the pine. After Stevens.. A B C , Fig. 71. — A, a microspore lea£ of the pine as seen from below, showing the pollen sacs. B, the same, seen from the side. C, a pollen grain; ii, the generative cell; b, the nucleus of the large vegetative cell; c, the bladder- like expansion of the outer wall of the pollen grain.. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the orig Stock Photo

RMRDWAN7–. Textbook of botany. Botany. Fig. 70. — A cluster o£ staminate cones of the pine. After Stevens.. A B C , Fig. 71. — A, a microspore lea£ of the pine as seen from below, showing the pollen sacs. B, the same, seen from the side. C, a pollen grain; ii, the generative cell; b, the nucleus of the large vegetative cell; c, the bladder- like expansion of the outer wall of the pollen grain.. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the orig

RMRDHG4W–. Essentials of botany. Botany; Botany. Pig. 123. Germination of Pollen Grain of an Angiosperm. (Much magnified and somewhat dia^ grammatic.) Pig. 122. Pollen Grains producing ^' ™*'^« S^ain, with germination con- siderably advanced. B, tip of pollen tube at a much later stage, after the tube nucleus has disappeared: g, the generative cell beginning to enter the tube;, t, the tube nucleus; s, sperm Tubes, on Stigma of a Lily. (Much magnified.) g, pollen grains; t, pollen tubes; p, papillse of stigma; e, canal or passage running toward ovary. cells formed from the generative cell. which contain

. Essentials of botany. Botany; Botany. Fig. 123. Germination of Pollen Grain of an Angiosperm. (JIuch magnified and somewhat dia- grammatic.) -1, entire grain, with germination con- siderably advanced. B, tip of pollen tube at a much later stage, after the tube nucleus has disappeared: g, the generative cell beginning to enter the tube; t, the tube nucleus; s, sperm cells formed from the generative cell. Fig. 122. Pollen Grains producing Tubes, on Stigma of a Lily. (JIuch magnified.) g, pollen grains; t, pollen tubes; p, papillse of stigma; c, canal or passage running toward ovary. which cont Stock Photo

RMRDWG4N–. Essentials of botany. Botany; Botany. Fig. 123. Germination of Pollen Grain of an Angiosperm. (JIuch magnified and somewhat dia- grammatic.) -1, entire grain, with germination con- siderably advanced. B, tip of pollen tube at a much later stage, after the tube nucleus has disappeared: g, the generative cell beginning to enter the tube; t, the tube nucleus; s, sperm cells formed from the generative cell. Fig. 122. Pollen Grains producing Tubes, on Stigma of a Lily. (JIuch magnified.) g, pollen grains; t, pollen tubes; p, papillse of stigma; c, canal or passage running toward ovary. which cont

. Morphology of spermatophytes. [Part I. Gymnosperms]. Gymnosperms; Plant morphology. Fig. 32.—Grinkgo Sifoja, development of male gametophyte: ,4, pollen grain collected April 24th, showing third nuclear division and the persistent vegetative cell (p),- X 500; S, a later stage, sliowing persistent vegetative cell {p), generative cell '{a), and tube nucleus {t), x 500; C, later stage, July 10th, the generative cell almost spherical, x"500; D, division of nucleus of generative cell into nuclei of stalk and body cells, July 11th, x 500; F, division of the body cell, the blepharoplasts being Stock Photo

RMRE2HR5–. Morphology of spermatophytes. [Part I. Gymnosperms]. Gymnosperms; Plant morphology. Fig. 32.—Grinkgo Sifoja, development of male gametophyte: ,4, pollen grain collected April 24th, showing third nuclear division and the persistent vegetative cell (p),- X 500; S, a later stage, sliowing persistent vegetative cell {p), generative cell '{a), and tube nucleus {t), x 500; C, later stage, July 10th, the generative cell almost spherical, x"500; D, division of nucleus of generative cell into nuclei of stalk and body cells, July 11th, x 500; F, division of the body cell, the blepharoplasts being

. Elements of botany. Botany. Fig. V22. Pollen Grains producing Tubes, on Stigma of a Lily. (Much magnified.) g, pollen grains; t, i^olleu tubes; p, papilhe of stigma; c, canal or passage running toward ovary. Fio. 123. Germination of I'oUen Grain of an Angiosperni. (Much magnified and somewhat dia- grammatic.) A, entire grain, with germination con- siderahly advanced. Ji, tip of pollen tube at a much later stage, after the tube nucleus has disappeared: g, the generative cell l)eginning to enter the tube; t, the tube nucleus; s, sperm cells formed from the generative cell. which contains mater Stock Photo

RMRE2JNH–. Elements of botany. Botany. Fig. V22. Pollen Grains producing Tubes, on Stigma of a Lily. (Much magnified.) g, pollen grains; t, i^olleu tubes; p, papilhe of stigma; c, canal or passage running toward ovary. Fio. 123. Germination of I'oUen Grain of an Angiosperni. (Much magnified and somewhat dia- grammatic.) A, entire grain, with germination con- siderahly advanced. Ji, tip of pollen tube at a much later stage, after the tube nucleus has disappeared: g, the generative cell l)eginning to enter the tube; t, the tube nucleus; s, sperm cells formed from the generative cell. which contains mater

. Morphology of spermatophytes. [Part I. Gymnosperms]. Gymnosperms; Plant morphology. / Fio. 22.—Cfycas revoluta, development of the ciliated male cell: .1, male gametophyte of three cells, vegetative or '' prothallial" cell (^), generative cell, and tube cell (^), X 500; B, the generative cell (a) rounded off, x 200; C, the generative cell (a) show- ing division of nucleus into stalk and body nuclei, x 500; D, fii-st appearance of blepharoplasts in enlarging body cell (6), and diminishing stalk nucleus (s), x 500; £, body cell (b) shortly before division, showing well-developed blepharop Stock Photo

RMRE2HWY–. Morphology of spermatophytes. [Part I. Gymnosperms]. Gymnosperms; Plant morphology. / Fio. 22.—Cfycas revoluta, development of the ciliated male cell: .1, male gametophyte of three cells, vegetative or '' prothallial" cell (^), generative cell, and tube cell (^), X 500; B, the generative cell (a) rounded off, x 200; C, the generative cell (a) show- ing division of nucleus into stalk and body nuclei, x 500; D, fii-st appearance of blepharoplasts in enlarging body cell (6), and diminishing stalk nucleus (s), x 500; £, body cell (b) shortly before division, showing well-developed blepharop

. Botany of the living plant. Botany; Plants. 534 BOTANY OF THE LIVING PLANT attached laterally (the generative cell), and a free nucleus (the tube nucleus) enclosed in cytoplasm which fills the rest of the grain.. Fig. 421. Pinus montana. A longitudinal section of a ripe male flower (xio). B, longitu- dinal section of a single stamen ( x 20). C, Transverse section of a stamen ( x 27). D, a ripe pollen grain of Pinus sylvestris. The obliterated prothallial cells are not shown. ( x 400.) (After Strasburger.) The male flower is thus a simple shoot bearing sporangia. The female flower may also be Stock Photo

RMRH8NJ6–. Botany of the living plant. Botany; Plants. 534 BOTANY OF THE LIVING PLANT attached laterally (the generative cell), and a free nucleus (the tube nucleus) enclosed in cytoplasm which fills the rest of the grain.. Fig. 421. Pinus montana. A longitudinal section of a ripe male flower (xio). B, longitu- dinal section of a single stamen ( x 20). C, Transverse section of a stamen ( x 27). D, a ripe pollen grain of Pinus sylvestris. The obliterated prothallial cells are not shown. ( x 400.) (After Strasburger.) The male flower is thus a simple shoot bearing sporangia. The female flower may also be

RMRG37AR–. California fish and game. Fisheries -- California; Game and game-birds -- California; Fishes -- California; Animal Population Groups; Pêches; Gibier; Poissons. ("lOjtt- G "4 0>1. FIGURE 5—A—Generative phase of primary oocyte showing association of chromosomes with the nuclear wall. NU = nucleus, NO = nucleolus. B—Budding and vacuolated nucleolus in primary oocyte. C—Lobed condition of apparent Golgi apparatus in primary oocyte. GA ^ apparent Golgi apparatus. D—Flattened condition of ap- parent Golgi apparatus (antecedent of lobed condition) in primary oocyte. GA = apparent Golgi

$. Botany for high schools. Botany. THE GYMNOSPERMS Other becomes a sperm mother cell, called the generative cell or the body cell. These cells move along in the apex of the tube. The pollen tube rests in the nucellus during win- ter. The following spring it begins growth again, and the nucleus of the generative, or body, cell divides into two sperm nuclei in the one cell. The female prothallium (endosperm) is developed sterile part of male gametophyte; a.c, central cell of an- {t-. fUp cnnrp oo.f^ {r^^r(A theridium; v.n., vegetative nucleus or tube nucleus of ^^^^ spuic ^.dbc (^iiULCl- the si Stock Photo$

RMRH84K1–. Botany for high schools. Botany. THE GYMNOSPERMS Other becomes a sperm mother cell, called the generative cell or the body cell. These cells move along in the apex of the tube. The pollen tube rests in the nucellus during win- ter. The following spring it begins growth again, and the nucleus of the generative, or body, cell divides into two sperm nuclei in the one cell. The female prothallium (endosperm) is developed sterile part of male gametophyte; a.c, central cell of an- {t-. fUp cnnrp oo.f^ {r^^r(A theridium; v.n., vegetative nucleus or tube nucleus of ^^^^ spuic ^.dbc (^iiULCl- the si

RMRDH6NM–. Morphology of gymnosperms. Gymnosperms; Plant morphology. Figs. 160-165.—Cycas revoluta: fig. 160, pollen grains at shedding stage; Xsoo, fig. 161, later stage, showing prothallial cell {p) and generative cell [g), the tube nucleus not shown; X200; fig. 162, generative cell divided, giving rise to stalk and body cells; Xsoo; fig. 163, the stalk nucleus {s) being crowded out, and blepharoplasts appearing in the body cell (6); X500; fig. 164, the body cell shortly before division, showing two well-developed blepharoplasts; X 750; fig. 165, the two male cells resulting from the division of the

. Carnegie Institution of Washington publication. sl.c.. FIG. 68.—Pollen grain, end of pollen tube, and fusion nucleus of Pinus stroiius.—(After Ferguson.) A, mature pollen grain. /' and/', remains of first and second prothallial cells; a. c., antheridial cell. B, pollen grain in which antheridial cell has divided. £.c., generative cell; st.c., stalk cell. C, distal end of pollen tube which is pushing between neck-cells of archegonium ; the male nuclei (s.n.) are of unequal size, v.n., tube nucleus ; st.c., stalk cell; i.e., cytoplasm of generative cell. D, first mitosis following fecundation. Stock Photo

RMRFWB96–. Carnegie Institution of Washington publication. sl.c.. FIG. 68.—Pollen grain, end of pollen tube, and fusion nucleus of Pinus stroiius.—(After Ferguson.) A, mature pollen grain. /' and/', remains of first and second prothallial cells; a. c., antheridial cell. B, pollen grain in which antheridial cell has divided. £.c., generative cell; st.c., stalk cell. C, distal end of pollen tube which is pushing between neck-cells of archegonium ; the male nuclei (s.n.) are of unequal size, v.n., tube nucleus ; st.c., stalk cell; i.e., cytoplasm of generative cell. D, first mitosis following fecundation.

. Colchicine in agriculture, medicine, biology, and chemistry. Colchicine; Colchicine. '% B t^. Ci D Fig. 2.4—Pollen tube cultures treated and untreated. A. A metaphase of generative cell of Lllium michiganensis without treatment. One per cent agar and 7 per cent sucrose, stained with iron alum haemotoxylin. B. Anaphase, Polygonatum commutatum un- treated. Stained with acetocarmine. C. Two microgametes and tube nucleus. D. Ar- rested metaphase, c-pairs, caused by adding 0.01 per cent colchicine to culture media. The duplications among c-pairs indicate polyploidy. There are 20 c-pairs but only Stock Photo

RMREJCMF–. Colchicine in agriculture, medicine, biology, and chemistry. Colchicine; Colchicine. '% B t^. Ci D Fig. 2.4—Pollen tube cultures treated and untreated. A. A metaphase of generative cell of Lllium michiganensis without treatment. One per cent agar and 7 per cent sucrose, stained with iron alum haemotoxylin. B. Anaphase, Polygonatum commutatum un- treated. Stained with acetocarmine. C. Two microgametes and tube nucleus. D. Ar- rested metaphase, c-pairs, caused by adding 0.01 per cent colchicine to culture media. The duplications among c-pairs indicate polyploidy. There are 20 c-pairs but only

. Fundamentals of botany. Botany. Fig. 299.—Cycas revoluta. a, Pollen grains at shedding stage; X 500; 6, later stage, showing prothallial cell {p) and generative cell (g), the tube- nucleus not shown; X 200; c, generative cell divided, giving rise to stalk- and body-cells; X 500; d, the stalk-cell-nucleus (s) being crowded out, and blepharoplasts appearing in the body cell (6); X 500; e, the body-cell shortly before division, showing two well-developed blepharoplasts; X 750; /, the two male cells resulting from the division of the body-cell; the beaks of the nuclei are attached to the cilia-b Stock Photo

RMRE2F8B–. Fundamentals of botany. Botany. Fig. 299.—Cycas revoluta. a, Pollen grains at shedding stage; X 500; 6, later stage, showing prothallial cell {p) and generative cell (g), the tube- nucleus not shown; X 200; c, generative cell divided, giving rise to stalk- and body-cells; X 500; d, the stalk-cell-nucleus (s) being crowded out, and blepharoplasts appearing in the body cell (6); X 500; e, the body-cell shortly before division, showing two well-developed blepharoplasts; X 750; /, the two male cells resulting from the division of the body-cell; the beaks of the nuclei are attached to the cilia-b

. The classification of flowering plants. Plants. 104 FLOWERING PLANTS [CH. the grains, but closes after pollination, the edges bending in- wards and pushing the grains on to the top of the nucellus, where they are retained in a sticky liquid excreted from the apex of the nucellus.. Fig. 4L A—C. Germination of microspore of Finns Laricio; p, vegetative cells; g, generative cell; t, tube-nucleus; s, stalk-cell; b, body-cell. A, May 25. B, June 15. C, May 1 in the following year. A and B x 300, C x 200. D. End of polleu-tube of Juniperus virginiana; m, male-cells, immediately in front are the nu Stock Photo

RMREK7YY–. The classification of flowering plants. Plants. 104 FLOWERING PLANTS [CH. the grains, but closes after pollination, the edges bending in- wards and pushing the grains on to the top of the nucellus, where they are retained in a sticky liquid excreted from the apex of the nucellus.. Fig. 4L A—C. Germination of microspore of Finns Laricio; p, vegetative cells; g, generative cell; t, tube-nucleus; s, stalk-cell; b, body-cell. A, May 25. B, June 15. C, May 1 in the following year. A and B x 300, C x 200. D. End of polleu-tube of Juniperus virginiana; m, male-cells, immediately in front are the nu

. Morphology of spermatophytes. [Part I. Gymnosperms]. Gymnosperms; Plant morphology. CONIPERALES 91 The third division immediately follows (Fig. 69, J), divid- ing the large antheridial cell into the primary spermatogenons. Fio. 69.—Pinus Larido, showing a series from the fonnation of the tetrads to the de- velopment of the pollen tube : p, vegetative cells; s, stalk cell; ft, body cell; i, tube nucleus : A and B, May 3d; C, May 10th ; D-G, May 20th ; H-J, May 25th; K, June 15th ; Z, May 1st (nearly a year after stage shown in Z"); x 600. cell or generative cell, and the tuhe cell (the s Stock Photo

RMRE2HGX–. Morphology of spermatophytes. [Part I. Gymnosperms]. Gymnosperms; Plant morphology. CONIPERALES 91 The third division immediately follows (Fig. 69, J), divid- ing the large antheridial cell into the primary spermatogenons. Fio. 69.—Pinus Larido, showing a series from the fonnation of the tetrads to the de- velopment of the pollen tube : p, vegetative cells; s, stalk cell; ft, body cell; i, tube nucleus : A and B, May 3d; C, May 10th ; D-G, May 20th ; H-J, May 25th; K, June 15th ; Z, May 1st (nearly a year after stage shown in Z"); x 600. cell or generative cell, and the tuhe cell (the s

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