. Outlines of zoology. Zoology. 6o REPRODUCTION AND LIFE HISTORY. the ovum was all-important, only needing the sperm's awakening touch to begin unfolding the miniature model. Fig. 27.—Spermatogenesis and polar bodies.—After Hertwig and Weismann. A'. Primitive germ cell of Ascaris megalocephala., var. bivalens (4 chromosomes). B'. Sperm mother cell (8 chromosomes). C. Two spermatocytes formed, each with 4 chromosomes (first reducing division). D'. Four spermatozoa formed, each with 2 chromosomes (second reducing division). A. Primitive germ cell (4 chromosomes). B. Fully developed ovum (8 chrom
. Outlines of zoology. Zoology. 6o REPRODUCTION AND LIFE HISTORY. the ovum was all-important, only needing the sperm's awakening touch to begin unfolding the miniature model. Fig. 27.—Spermatogenesis and polar bodies.—After Hertwig and Weismann. A'. Primitive germ cell of Ascaris megalocephala., var. bivalens (4 chromosomes). B'. Sperm mother cell (8 chromosomes). C. Two spermatocytes formed, each with 4 chromosomes (first reducing division). D'. Four spermatozoa formed, each with 2 chromosomes (second reducing division). A. Primitive germ cell (4 chromosomes). B. Fully developed ovum (8 chromosomes). C. Formation of first polar body () (first reducing division). D. Formation of second polar body {j>) (second reducing division). First polar body may divide into two. which it contained. Others, nicknamed "animalculists," were equally confident that the sperm was essential, though. 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 Thomson, J. Arthur (John Arthur), 1861-1933. Edinburgh, Glasgow and London, H. Frowde and Hodder & Stoughton
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Keywords: ., bookauthorth, bookcentury1800, bookdecade1890, booksubjectzoology
