. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 344 ROBERT CHAMBERS. plete fertilization membrane formed around the egg except at the two torn spots and cleavage followed. Endoplasmic exovates were also produced which remain con- nected by a bridge of protoplasm to the collapsed cortical portion. FIG. 25. a, nucleated exovate of internal cytoplasm produced by squashing a starfish egg. b, fragments inseminated after the endoplasmic sphere was pinched off. Only the ectoplasmic remnant forms a fertilization membrane. c, the endoplasmic sphere remains inert and nonfertilizabl
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 344 ROBERT CHAMBERS. plete fertilization membrane formed around the egg except at the two torn spots and cleavage followed. Endoplasmic exovates were also produced which remain con- nected by a bridge of protoplasm to the collapsed cortical portion. FIG. 25. a, nucleated exovate of internal cytoplasm produced by squashing a starfish egg. b, fragments inseminated after the endoplasmic sphere was pinched off. Only the ectoplasmic remnant forms a fertilization membrane. c, the endoplasmic sphere remains inert and nonfertilizable (cf. Fig. 12). FIG. 26. a, starfish egg squashed producing two endoplasmic exovates. b, the nucleated exovate was pinched off. Upon insemination the other ex- ovate drew back into the ectoplasmic remnant which formed a fertilization membrane. c, d and e, the ectoplasmic remnant underwent segmentation showing that the disturbance due to the squashing does not prevent segmen- tation. The endoplasmic sphere remains inert (d). of the egg. On being inseminated the exovate either is drawn back into the cortical portion as the latter rounds up with the formation of a fertilization membrane or is pinched off, after which it remains as an inert body. The possibility suggested itself that the substance which renders an egg fertilizable has a tendency to collect in the surface film of an egg and that, if an exovate remained in organic continuity with the egg, this substance might spread to the surface film of the exovate, thus rendering it fertilizable. Endoplasmic exovates were, therefore, produced which remained connected for varying lengths of time with the cortical portion of the egg. Some of the exovates remained connected for as long as fifteen minutes. Before insemi-. 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 w
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
