Fungi, Ascomycetes, Ustilaginales, Uredinales . g. 68. Humaria granulata Quel.; a. fusion of nuclei in oogonium, X3200; ^.oogoniumgiving rise to ascogenous hyphae, x isjo; after Blackman ami Fraser. Vegetative cells grow up and invest the archicarp, forming a closepseudoparenchymatous sheath in which the ascogenous hyphae ramify.They give rise at last to asci in the usual way. Four chromosomes have been recorded in the ascogenous hyphae,eight in the first division in the ascus and four in the two subsequent IV] IKXIZAI.KS 11 • mitoses. This implies that the gametophytic number is four, and tha
![Fungi, Ascomycetes, Ustilaginales, Uredinales . g. 68. Humaria granulata Quel.; a. fusion of nuclei in oogonium, X3200; ^.oogoniumgiving rise to ascogenous hyphae, x isjo; after Blackman ami Fraser. Vegetative cells grow up and invest the archicarp, forming a closepseudoparenchymatous sheath in which the ascogenous hyphae ramify.They give rise at last to asci in the usual way. Four chromosomes have been recorded in the ascogenous hyphae,eight in the first division in the ascus and four in the two subsequent IV] IKXIZAI.KS 11 • mitoses. This implies that the gametophytic number is four, and tha Stock Photo](https://c8.alamy.com/comp/2AN4560/fungi-ascomycetes-ustilaginales-uredinales-g-68-humaria-granulata-quel-a-fusion-of-nuclei-in-oogonium-x3200-oogoniumgiving-rise-to-ascogenous-hyphae-x-isjo-after-blackman-ami-fraser-vegetative-cells-grow-up-and-invest-the-archicarp-forming-a-closepseudoparenchymatous-sheath-in-which-the-ascogenous-hyphae-ramifythey-give-rise-at-last-to-asci-in-the-usual-way-four-chromosomes-have-been-recorded-in-the-ascogenous-hyphaeeight-in-the-first-division-in-the-ascus-and-four-in-the-two-subsequent-iv-ikxizaiks-11-mitoses-this-implies-that-the-gametophytic-number-is-four-and-tha-2AN4560.jpg)
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Fungi, Ascomycetes, Ustilaginales, Uredinales . g. 68. Humaria granulata Quel.; a. fusion of nuclei in oogonium, X3200; ^.oogoniumgiving rise to ascogenous hyphae, x isjo; after Blackman ami Fraser. Vegetative cells grow up and invest the archicarp, forming a closepseudoparenchymatous sheath in which the ascogenous hyphae ramify.They give rise at last to asci in the usual way. Four chromosomes have been recorded in the ascogenous hyphae, eight in the first division in the ascus and four in the two subsequent IV] IKXIZAI.KS 11 • mitoses. This implies that the gametophytic number is four, and that thegemini are formed immediately after the fusion in the oogonium, so that inthe ascogenous hyphae there are four bivalent instead of eight univalentchromosomes. In the meiotic prophase which follows the fusion in theascus, there is a double number of gemini, since two sporophytic nucleihave united. In Humaria granulata, the antheridium has disappeared and normalfertilization is replaced by fusion of female nuclei in pairs in the oogonium.. Fig. 69. Humaria rutilans (Fr.) Sacc; very young ascocai p, x soo. In another species of this genus, Humaria rutilans1, reduction has gone yetfurther and not even an archicarp is produced. The apothecium arises asa dense weft of tangled filaments, which for a time differ from one anotheronly in the relatively thick walls of the outer hyphae, and the richer proto-plasmic content of the inner (fig. 69). Each cell of the weft contains oneor a few nuclei. After a while the nuclei in the central part of the massmay be seen to be of two sizes, and the smaller have been found to fuse in 1 Humaria rutilans |Kr.| Sacc. = Peziza rutilans Fr. in Boudier, horn r, PI. 315.G.-V. 8 H4 DISCOMYCETES [CH. pairs (fig. 70 a), giving rise to the larger. Sometimes in connection withthis process a nucleus migrates through the wall from one cell to another(fig. 70 b), as in prothallia of ferns. Thus in H. rutilans, where the sexualorgans are completely lacking,