The first principles of heredity; with 75 illustrations and diagrms . B. Fig. 35.—Development of Sagitta. (After Hertwig.){From Weismann, The Germ-Plasm.)A, B, C, three successive stages ; g, germ-cells. therefore not immediately separated from the otheridioplasm of the body, but is carried along in a latent statein some of the primitive body-cells, during a few of theirearlier stages, until it is separated in the form of distinctgerm-cells. Now, this differentiation of the germ-cellsmay be put off until very late in the development of thebody structure, the germ-plasm being handed down in ala
The first principles of heredity; with 75 illustrations and diagrms . B. Fig. 35.—Development of Sagitta. (After Hertwig.){From Weismann, The Germ-Plasm.)A, B, C, three successive stages ; g, germ-cells. therefore not immediately separated from the otheridioplasm of the body, but is carried along in a latent statein some of the primitive body-cells, during a few of theirearlier stages, until it is separated in the form of distinctgerm-cells. Now, this differentiation of the germ-cellsmay be put off until very late in the development of thebody structure, the germ-plasm being handed down in alatent, inactive state from cell to cell, without in any wayinfluencing at any stage the body-cell in which it happensto be contained. The route which the germ-plasmfollows—, the succession of cells through which it passesuntil it finally splits off in the form of distinct germ-cells— THEORIES OF HEREDITY 6i is always the same for any given species, and has beencalled by Weismann the germ-track. Fig. 36 will makethis clear. We have, then, if not a continuity o
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisherlondo, bookyear1910
