. The cell in development and inheritance. Cells. 244 j^Enrcriox of T//r: cuA-chi/osoj/ns deeper meanin-; of the phenomena was first seriously considered by Weismann in his essays of 1885 and 1887 ; and, although his conclu- sions were of a highly speculative character, they nevertheless gave so. Fig. 120. — Reduction in the spermatogenesis oi Ascaris megalocephala,\2LX. bivaleiis. [Bkauer.] 1 A-G. Successive stages in the division of the primary spermatocyte. The original reticulum undergoes a veiy early division of the chromatin-granules which then form a doubly split spireme- thread, i5. Th
. The cell in development and inheritance. Cells. 244 j^Enrcriox of T//r: cuA-chi/osoj/ns deeper meanin-; of the phenomena was first seriously considered by Weismann in his essays of 1885 and 1887 ; and, although his conclu- sions were of a highly speculative character, they nevertheless gave so. Fig. 120. — Reduction in the spermatogenesis oi Ascaris megalocephala,\2LX. bivaleiis. [Bkauer.] 1 A-G. Successive stages in the division of the primary spermatocyte. The original reticulum undergoes a veiy early division of the chromatin-granules which then form a doubly split spireme- thread, i5. This shortens (6'), and breaks in two to form the two tetrads (Z) in profile, iS viewed endwise). F. G. H. First division to form two secondary spermatocytes, each receiving two dyads. /. Secondary spermatocyte. T. K. The same dividing. L. Two resulting spermatids, each with two single chromosomes and a centrosome. great a stimulus to the study of the entire problem that his views deser\'e special attention. Weismann's interpretation was based on a remarkable paper published by Wilhelm Roux in 1883,^ in which are 1 For division of the spermatogonia see Fig. 55; for the corresponding phenomena in var. univalens see Fig. 148. ' Uber Jie BeJetittiug der 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 Wilson, Edmund B. (Edmund Beecher), 1856-1939. New York Macmillan
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectcells, bookyear1906
