. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 278 ROBERT CHAMBERS AND EDWARD L. CHAMBERS 1st p b. 170 mm. FIGURE 3. Three eggs inseminated 25 minutes after deposition in sea water and then bisected at different times so as to have sperm pronucleus in one fragment and egg nucleus in the other. A. Cut at 35 minutes (10 minutes after insemination), A,. At 97 minutes, A2. Beginning sperm aster, , appears in one fragment and first in companion fragment. B. Cut at 50 minutes (25 minutes after insemination), B,. At 99 minutes, B2. Beginning sperm aster appears in one
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 278 ROBERT CHAMBERS AND EDWARD L. CHAMBERS 1st p b. 170 mm. FIGURE 3. Three eggs inseminated 25 minutes after deposition in sea water and then bisected at different times so as to have sperm pronucleus in one fragment and egg nucleus in the other. A. Cut at 35 minutes (10 minutes after insemination), A,. At 97 minutes, A2. Beginning sperm aster, , appears in one fragment and first in companion fragment. B. Cut at 50 minutes (25 minutes after insemination), B,. At 99 minutes, B2. Beginning sperm aster appears in one fragment and beginning second in companion fragment. C. Cut at 74 minutes, just after the first has formed, d. At 101 minutes, C-. Be- ginning sperm aster appears in one fragment and completed in companion fragment. D. Condition of all three bisected eggs at 170 minutes. Sperm-haploid fragment has cleaved, while egg nucleus, , of companion fragment has taken a central position and remained inactive. DISCUSSION The results presented in this paper stress two major features concerning the events after the material of the germinal vesicle has mixed with the cytoplasm of the egg. One deals writh the maturation of the karyocytoplasm; the other, with the fertilization process of the male and female nuclear elements in their relations to the maturing karyocytoplasm. Delage (1899) had already surmised that the dissolution of the germinal vesicle is essential to maturation and fertilizability of the sea urchin egg, and confirmed it from his merogonic experiments (1901) on the immature eggs of Asterias glacial is. In our experiments with Asterias forbcsii the disappearance of the germinal vesicle and the mixing of its hyaline fluid with the granular cytoplasm lasts about 10-15 minutes. The resulting karyocytoplasm contains the definitive egg Please note that these images are extracted from scanned page images that may have been digitally enhanced for readabili
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