The cell in development and inheritance . e changes in the body, orsoma, should so affect the protoplasm of the germ-cells as to causecorresponding changes to appear in the offspring. How, he asks,can the increased dexterity and power in the hand of a trained piano-player so affect the molecular structure of the germ-cells as to pro-duce a corresponding development in the hand of the child . It isa physiological impossibility. If we turn to the facts, w^e find, Weis-mann affirms, that not one of the asserted cases of transmission ofacquired characters will stand the test of rigid scientific sc
The cell in development and inheritance . e changes in the body, orsoma, should so affect the protoplasm of the germ-cells as to causecorresponding changes to appear in the offspring. How, he asks,can the increased dexterity and power in the hand of a trained piano-player so affect the molecular structure of the germ-cells as to pro-duce a corresponding development in the hand of the child . It isa physiological impossibility. If we turn to the facts, w^e find, Weis-mann affirms, that not one of the asserted cases of transmission ofacquired characters will stand the test of rigid scientific scrutiny. Itis a reversal of the true point of view to regard inheritance as takingplace from the body of the parent to that of the child. The childinherits from the parent germ-cell, not from the parent-body, and thegerm-cell owes its characteristics not to the body which bears it, butto its descent from a preexisting germ-cell of the same kind. Thusthe body is, as it were, an offshoot from the germ-cell (Fig. 5). As ^ Line of \£) Line of inheritance. GFig. 5. — Diagram illustrating Weismanns theory of inheritance. G. The germ-cell, which by division gives rise to the body or soma (5) and to new germ-cells(G) which separate from the soma and repeat the process in each successive generation. far as inheritance is concerned, the body is merely the carrier of thegerm-cells, which are held in trust for coming generations. Weismanns subsequent theories, built on this foundation, havegiven rise to the most eagerly contested controversies of the post-Darwinian period, and, whether they are to stand or fall, have playeda most important part in the progress of science. For aside from thetruth or error of his special theories, it has been Weismanns greatservice to place the keystone between the work of the evolutionistsand that of the cytologists, and thus to bring the cell-theory and the 14 INTRODUCTION evolution-theory into organic connection. It is from the point of vie
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectcells, bookyear1902
