38 Art Examination of Weismannism. 



it appears that no small corroboration is lent to Weis- 

 mann's views by these histological observations. And. 

 more particularly, if we suppose with him that the 

 material in question is restricted to that portion oi 

 the segregating nuclear matter which is called the 

 "nuclear thread V' in the formation of the "loops" 

 or " rods " of this substance we seem to have pre- 

 sented a visible expression of the marshalling of " the 

 carriers of heredity/' and the successive passage of the 

 originally generalized " germ-plasm " of the germ-cell 

 into the ever more and more specialized "nucleo- 

 plasms" of the somatic-cells. Indeed, the new theory 

 of heredity, when thus brought into relation with the 

 new results of histological observation, appears so well 

 to fit the latter, that one would be sorry to find 

 the coincidence unmeaning, or the theory false. But. 

 without passing any criticism, it is sufficient to note 

 that the question whether or not the theory is true — 

 and therefore correctly interprets the phenomena of 

 karyokinesis. — must depend chiefly on whether it 

 be eventually proved that the " nuclear thread " is 

 indeed the only part of a germ-cell, or even the 

 only part of a tissue-cell, which is concerned in con- 

 trolling the phenomena of heredity on the one hand, 

 and of ontogeny on the other. Into this question, 

 however, I do not propose to enter. It will be enough 

 to assume, for the sake of argument, that Weismann's 

 view of the matter will eventually prove to be true. 

 At the same time, we must remember that at present 

 this view as to the nuclear thread being the sole 



1 See Part I, figs. 36, 37, and 38. The substance of this thread, in 

 the various phases of its segmentation, is the " chromatin," as there 

 depicted, and so called because it takes a stain better than other parts 

 of the nucleus — thus showing some distinctive character. 



