Later Additions up to the year 1892. ?>7 



I do not see that it makes any substantial difference to 

 Weismann's theory of heredity, whether we speak of 

 germ-plasm being converted into " somato-plasm," 

 or into " idio-plasm " plus " somatic-idio-plasm," plus 

 " cytoplasm." But as Weismann himself thinks that 

 it does make some great difference whether we adhere 

 to his original generic term " somato-plasm," or adopt 

 his newer and more specific terms as just enumerated, 

 I append in extenso the most recent exposition of his 

 views upon this subject 1 . 



Before quitting this somewhat complicated addition 

 to the original theory of germ-plasm, I must briefly 

 allude to the descriptions and illustrations of karyo- 

 kinesis which were given in Part I of Darwin and after 

 Darwin, for the prospective benefit of any general 

 readers who might afterwards be sufficiently interested 

 in Weismann's speculations to desire a statement of 

 the main facts on which this further development of his 

 theory rests. It seemed undesirable to burden the 

 present volume with an account of recent investigations 

 so well known to naturalists, while, on the other hand, 

 it was clearly desirable that such an account should be 

 given somewhere, if the speculations in question were 

 to be rendered intelligible to anybody else. There- 

 fore I must here request those of my readers who are 

 not already acquainted with the matter to consult 

 pp. 128-134 of Part I. It will there be seen how 

 enormously complex are the visible processes which 

 take place in the nucleus of a germ-cell (and likewise 

 of a somatic-cell), preparatory to its division ; and 

 therefore, supposing that the nucleus alone contains 

 the material concerned in the phenomema of heredity, 



1 See close of Appendix. 



