. Embryology. Embryology; Embryology; genealogy. Fig. 12. A sea urchin egg after exposure to centrifugal force becomes strati- fied into layers of granules and clear protoplasm. C, Ct gives the direction of the applied centrifugal force. The embryo which develops from the centrifuged egg (right) is normal except for pigmentation. The polarity of the egg has not been altered by centrifugation. clear protoplasm without any microscopically visible particles in it, called the hyaline protoplasm. Thus we have a means of shifting all the microscopically visible con- stituents of the egg and of movin
. Embryology. Embryology; Embryology; genealogy. Fig. 12. A sea urchin egg after exposure to centrifugal force becomes strati- fied into layers of granules and clear protoplasm. C, Ct gives the direction of the applied centrifugal force. The embryo which develops from the centrifuged egg (right) is normal except for pigmentation. The polarity of the egg has not been altered by centrifugation. clear protoplasm without any microscopically visible particles in it, called the hyaline protoplasm. Thus we have a means of shifting all the microscopically visible con- stituents of the egg and of moving them away from their original positions. If any of these constitutents—the fat droplets, the pigment granules, or this second type of unpigmented granules—are responsible for the organization of the egg, then a completely distorted larva should result. As a matter of fact, the strongly centrifuged egg develops into a perfectly normal larva when fertilized. Figure 12 shows one of these larvae. Other larvae may show a shift in the position of the pigment. It may all be concentrated at one end of the larva; or on the side of the larva, so that one side is pigmented and the other is not. But the larvae are perfectly normal in all essential respects. More than that, it has been found that if the egg is exposed to very high centrifugal forces in an ultracentrifuge, the egg becomes torn apart so that its components are separated as cream is separated from milk, and parts of the egg almost entirely free of granules are obtained. These parts of the egg, practically free of any microscopically visible granules, may develop into perfect larvae. Therefore, none of the microscopically visible com- ponents of the endoplasm of the egg can have anything to do with its organization. And thus we must conclude that the organization depends upon some of the finer structure of protoplasm which is not disturbed by the Please note that these images are extracted from scanned page
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Keywords: ., boo, bookcentury1900, booksubjectembryology, booksubjectgenealogy
