WEI SM ANN'S CONCESSIONS. 177 



But this "was only a beginning of the almost complete retreat 

 that he has now made in his last work on the Germ-Plasm. As 

 before, it seems to have been the phenomena which the vegetable 

 kingdom presents that most obstinately refuse to adapt them- 

 selves to the mechanical theory of heredity of which he is the 

 author. Before these facts his fundamental distinction between 

 the blastogenic and the somatogenic idioplasm breaks down com- 

 pletely, and here at least he is " compelled to assume that most, 

 if not all, of the cells contain all the primary constituents of the 

 species in a latent condition." * After carefully considering such 

 cases as those of Bryophyllum and Begonia, almost any part of 

 which may be made to grow if properly situated, he admits that 

 such observations " apparently prove that ' every small fragment 

 of the members of a plant contains the elements from which the 

 whole complex body can be built up, when this fragment is iso- 

 lated under suitable external conditions.' " f 



Before passing to the major admissions of Weismann it may 

 be well to mention a few of the " doubtful phenomena of heredity " 

 which, in case they really occur, form such a stumbling block to 

 his system. On this side of the water one is amused at the state- 

 ment that " blue grains occasionally occur among the yellow ones 

 in cobs of the yellow-grained maize {Zea) after fertilization with 

 the pollen of a blue-grained species." X There is probably only 

 one " species " of Indian corn, but the cultivated varieties are end- 

 less, and every farmer's boy knows that it is of the greatest im- 

 portance to keep these apart, so that the ears will " fill " with the 

 same kind of kernels. Few American farmers would hesitate to 

 stake their farms on the much more than " occasional " occurrence 

 of different kinds of kernels on the same cob in a field where 

 different varieties are planted together. 



As regards the numerous cases of the alleged transmission of 

 characters derived from one sire to the offspring of a subsequent 

 sire, though disposed to discredit the evidence, he nevertheless 

 admits their possibility to a limited extent. For he says of them : 

 ** We may, however, at any rate suppose that this so-called ' in- 

 fection,' if not altogether deceptive, only occurs in rare instances, 

 and by no means regularly, or at most only in some cases." * 



Here we have again, as in the general case above considered, a 

 characteristic Weismaniiian argument, shifting the point from 

 the qualitative to the quantitative, from the principle to the de- 

 gree, which reminds one very forcibly of Jack Easy's wet nurse 



* The Germ-Plasm, p. 206. The Italics are his in this and all subsequent passages, 

 f Ibid., p. 212. The words quoted by Prof. Weismann appear to be taken from 

 De Vries. 



X Ibid., p. 383. * Ibid., p. 385. 



VOL. XLV. 13 



