54 An Examination of Weismannism. 



single tissues, or a mere cicatrix, depends only on 

 the "'•' ontogenetic grade " of differentiation which 

 this diffused nucleo-plasm has (or has not) previously 

 undergone. Moreover, as we have already seen, at 

 whatever ontogenetic grade of differentiation it may 

 be present in a given somatic-tissue, it must there be 

 capable of indefinite self-multiplication. Therefore, 

 in all these respects this ''formative nucleo-plasm "' (or 

 idio-plasm-B) of Weismann precisely resembles the 

 •' formative material" (or gemmules) of Darwin. 



Lastly, as De Vries has pointed out 1 , there must 

 be at least as many divisions and subdivisions in 

 the substance of germ-plasm, as there are differences 

 between the somatic organs, tissues, and even cells, 

 to which germ-plasm eventually gives rise — no matter 

 through how many ontogenetic grades of idio-plasm 

 it may first have to pass. Or, in other words, we must 

 accept, as the material basis of heredity, ultimate 

 particles - of germ-plasm, which are already differen- 

 tiated into as many diverse categories as there are 

 differences between all the constituent parts of the 

 resulting soma; for. as shown in the Appendix, no 

 change in the facts of the case has been shown by 

 simply changing the original term c; germ-plasm " into 

 " idio-plasm." wherever the phenomena of ontogeny 

 are concerned. It may be convenient, for the sake of 

 presenting newer additions to the theory, to restrict 

 the term " germ-plasm " to '■ idio-plasm of the first 

 ontogenetic stage " ; but as idio-plasms of all subse- 



1 Intracellulare Pangenesis, s. 55. 



2 I employ the term " particles," instead of "molecules," because 

 although Weismann and his followers seem to prefer the latter term, 

 I can scarcely imagine that they intend to use it in its original, or 

 chemical, sen-e. 



