1 86 An Examination of Weismannism, 



that the former becomes converted into the latter at each 

 ontogeny. At any rate, he allows that Vines' criticism upon 

 this head is sound. But he is strongly of the opinion that, 

 by means of a later emendation of his theory as originally 

 published, he has succeeded in obviating these difficulties 

 in ioto. For my own part, as already several times observed 

 in the text, I cannot in the least perceive that such is the 

 case ; and therefore I will quote in exfenso what he has said 

 in answer to Professor Vines. It will be seen that his newer 

 emendation of the theory consists in substituting for his 

 original "somato-plasm" two substances, which are called 

 respectively "somatic idio-plasm'' and "cytoplasm." And 

 it is by means of this substitution that he thinks he has, in 

 some way or another, overcome the contradiction involved in 

 the doctrine (and, as it still seems to me, the essential 

 doctrine of his whole theory of heredity) that " germ-plasm " 

 becomes converted into " somato-plasm " during the course 

 of every ontogeny. The following, at any rate, is his latest 

 utterance upon the subject : — 



I believe that the objections which Professor Vines makes to 

 my theory of the continuity of germ-plasma rest solely on an 

 unintentional confusion of my ideas, as he compares the opinions 

 expressed in the second essay with those of the later ones, 

 with which they do not tally. I will endeavour to make this 

 clear. In this second essay (1883) I contrasted the body (soma) 

 with the germ-cells, and explained heredity by the hypothesis 

 of a " Vererbungs-substanz " in the germ-cells (in fact the germ- 

 plasma\ which is transmitted without breach of continuity from 

 one generation to the next. I was not then aware that this lay 

 only in the nucleus of the ovum, and could therefore contrast 

 the entire substance of the ovum with the substance of the 

 body-cells, and term the latter " somato-plasm." In Essay IV 

 (1885) 1 had arrived, like Strasburger and O. Hertwig, at the 

 conviction that the nuclear substance, the chromatin of the 

 nuclear loops, was the carrier of heredity, and that the body of 

 the cell was nutritive but not formative. Like the investigators 



