CONJUGATION AND INHERITANCE 149 



view. The other view largely, if not entirely, removes these diffi- 

 culties, nor does it introduce any fresh crop of serious difficulties. 

 We may regard, then, the idioplasms from the two parent 

 forms as undergoing a true chemical combination, 1 the resultant 

 idioplasm of the new generation being in truth a new idioplasm 

 not possessing the identical properties of that of either parent, 

 but being intermediate, tending in its characters and constitution 

 toward the constitution of either one or the other according, it 

 may be, to the number or chemical activity of the molecules of 

 one or other parent entering into combination. Weismann 

 supports his view by pointing out that for a certain period 

 the maternal and paternal materials in the chromosomes of the 

 daughter nuclei remain distinct, and reaches the bold and 

 utterly unsupported conclusion that when the chromosomes fuse 

 to form the irregular network pervading the nucleus, their 

 constituents nevertheless remain distinct and sharply separable 

 from those of the other chromosomes. But we have no evidence, 

 in the first place, that the chromosomes alone contain the idio- 

 plasm, that chromatin and idioplasm are identical. Everything 

 points to the fact that the idioplasm is contained in the 

 nucleus, but we cannot with certainty advance further. It 

 may be that the chromatin is but the cystoplasmic framework, 

 the mechanism, as it were, by which the idioplasm is distributed. 



If the germ cells of both parents possess certain loosely 

 attached or unstable side-chains of more recent acquirement, 

 which are of like nature, there is no sufficient reason why the 

 protoplasm of the offspring should not also possess them. We 

 can thus realize how it is that abnormal features present in both 

 parents may be equally or more prominent in the offspring. 

 But in general we must recognize that, the parents varying in 

 different directions, the tendency of conjugation is to preserve 

 the mean, to bring about an approach to uniformity in the 

 constitution of the idioplasm of successive generations of one 

 species exposed to like influences. 



I need scarcely say that in these higher unicellular organisms 

 which present conjugation the cell already presents a nucleus, 

 and that everything indicates that this nucleus is the controlling 



1 [It will be recalled from what was said in Part I. that I no longer accept 

 this hypothesis of chemical combination. For some years I have replaced it 

 by that of interchange of side-chains.] 



