Quarterly journal of microscopical science . after karyogamic union of thenuclei has taken place without any transference of cytoplasm.After noting that here, at least, conjugation is an essentiallynuclear process, we proceed to infer from the coexistence ofconditions 1 and 2 that they are correlated phenomena. Letus consider the process after the second mitosis and elimina-tion of the three rejection-nuclei. 46 MABCtJS M. HARTOG. The following schema contrasts the conjugation of theDesmid Closteriunij and of a Ciliate. The zygote of the Closterium is totally different from thegametes, whose s

Quarterly journal of microscopical science . after karyogamic union of thenuclei has taken place without any transference of cytoplasm.After noting that here, at least, conjugation is an essentiallynuclear process, we proceed to infer from the coexistence ofconditions 1 and 2 that they are correlated phenomena. Letus consider the process after the second mitosis and elimina-tion of the three rejection-nuclei. 46 MABCtJS M. HARTOG. The following schema contrasts the conjugation of theDesmid Closteriunij and of a Ciliate. The zygote of the Closterium is totally different from thegametes, whose s Stock Photo
Preview

Image details

Contributor:

The Reading Room / Alamy Stock Photo

Image ID:

2AJ6569

File size:

7.1 MB (169.6 KB Compressed download)

Releases:

Model - no | Property - noDo I need a release?

Dimensions:

1869 x 1337 px | 31.6 x 22.6 cm | 12.5 x 8.9 inches | 150dpi

More information:

This image is a public domain image, which means either that copyright has expired in the image or the copyright holder has waived their copyright. Alamy charges you a fee for access to the high resolution copy of the image.

This image could have imperfections as it’s either historical or reportage.

Quarterly journal of microscopical science . after karyogamic union of thenuclei has taken place without any transference of cytoplasm.After noting that here, at least, conjugation is an essentiallynuclear process, we proceed to infer from the coexistence ofconditions 1 and 2 that they are correlated phenomena. Letus consider the process after the second mitosis and elimina-tion of the three rejection-nuclei. 46 MABCtJS M. HARTOG. The following schema contrasts the conjugation of theDesmid Closteriunij and of a Ciliate. The zygote of the Closterium is totally different from thegametes, whose structure can only be obtained afresh by avery complex reorganisation and after protracted rest. TheCiliate, on the contrary, carries away from conjugation itscytoplast with all its complexity retained, and yet has anucleus of the same form as that of the zygote of Clos-terium. The process then seems to involve the suppressionof formation of proper gametes, in order to gain the advantageof the retention of the cytoplasmic body unchanged. A N. Fig. 7.—Comparisons of three stages of the processes immediately leadingup to conjugation in Closterium (A) and Paramoecium (B). In each casetwo zygote-nuclei of the value (N + M = Z) are formed, but the cyto-plasts are unchanged in B, and totally altered in A. Having found a key to the final processes of conjugation wecan step back, and consider the first two mitoses with the form=ation of the rejection-nuclei. We may fairly regard thesealsQ as attempts to form a plurality of gametes comparablewith the processes observed in certain Fucacese, the positionin the cytoplast determining which nuclei shall be rejected.Possibly, too, the failing energies of the meganucleus at thisstage are insufficient to determine the division of the cytoplast; SOME PROBLEMS OF REPRODUCTION. 47 indeed^ the fact that cytoplastic division remains in abeyanceduring the absence of a meganucleus in working order is anadditional argument for regarding this as a dire

Save up to 70% with our image packs

Pre-pay for multiple images and download on demand.

View discounts