. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 3O W. S. SUTTON. which, as we have seen, projected into a common chamber of the nucleus. To such a conclusion additional weight is added by the occasional finding of telophases of the last spermatogonial generation which actually shows such a fusion (Fig. 8). Fir,. 8. Telophase of secondary spermatogonium of the last generation showing synapsis. Only a few of the chromosomes are shown and as in Fig. 4 ; to avoid con- fusion the sacculations are drawn only to the point where they cross one another. The four parts of
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 3O W. S. SUTTON. which, as we have seen, projected into a common chamber of the nucleus. To such a conclusion additional weight is added by the occasional finding of telophases of the last spermatogonial generation which actually shows such a fusion (Fig. 8). Fir,. 8. Telophase of secondary spermatogonium of the last generation showing synapsis. Only a few of the chromosomes are shown and as in Fig. 4 ; to avoid con- fusion the sacculations are drawn only to the point where they cross one another. The four parts of each spireme, marked off by the longitudinal split and the line of fusion, may be traced through all the pro- phases up to the metaphase, where they are clearly seen to become the four parts of the tetrad. These facts seem to me to leave no escape from the conclusion that in the completed tetrad the longitudinal split represents merely the usual division of a chromosome into equivalent chromatids ; but the transverse mark- ing separates two spermatogonial chromosomes which have conju- gated end-to-end in synapsis} Notwithstanding the fact that no continuous spireme is formed, the various spiremes of the larger group (16 in spermatogonia, 8 in spermatocytes) in any nucleus are at any given period always of approximately the same diameter and the same degree of con- centration. Their respective lengths may therefore be taken as a measure of their respective volumes, and accordingly the longer 1Cf. Montgomery, T. H., Jr. (1901), " The Spermatogenesis of Pcripatus (Peri- fatopsis) Balfouri up to the Formation of the Spermatid," Zool. Ja/i>-/>., XV.; also "A Study of the Chromosomes of the Germ Cells of the Metazoa," Trans. Amer. Phil. Soc., Vol. 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 ori
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