An Examination of Weismannism

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated.1893 Excerpt: ... CHAPTER III.... f Weismann's Theory Of Heredity (1891). We now proceed to examine Weismann's theory of germ-plasm, and as this in its various developments has now become a highly complex theory; we had best begin by marking out the lines on »v' ich the examination will be conducted. As I have already pointed out, the Wcismannian system is not concerned only with the physiology of reproduction: it is concerned also--and in an even larger measure--with the doctrine of descent. The theory of germ-plasm as a whole is very much more than a theory of heredity; it is a new theory of evolution. The latter, indeed, is deduced from the former; but although the two are thus intimately related, they are nevertheless not mutually dependent. For the relationship is such that the new theory of evolution stands upon the basis supplied by the new theory of heredity, and although it follows from this that if the latter were disproved the former would collapse, it does not follow that if the former were to be found untenable the latter must necessarily be negatived. Hence, for the sake of clearness, and also for the sake of doing justice to both theories, we had best deal with them separately. The present chapter, then, will be devoted to examining Wcismann's theory of heredity, while the ensuing chapter will be concerned with his sequent theory of evolution. Again, Wcismann's theory of heredity stands on his fundamental postulate--the continuity of germplasm; and also on a fact well recognized by all other theories cf heredity, which he calls the stability of germ-p' m. Hut his sequent theory of evolution stands not only on this fundamental postulate, and on this well-recognized fact; it requires for its logical basis two further postulates--viz., that germ-plasm has be...