Introductory 21 



ined to make up largely or wholly the chromosomes. 



A striking example of the rapid progress made by ele- 

 mciitalism toward its own extinction through contracting 

 itself to nothingness is furnished by the course of speculation 

 about ultimate biological units from tlie period of Spencer 

 and Darwin to the present moment. Spencer's physiological 

 units were by no means restricted to the germ-cells but 

 were held to permeate the whole organism. In this the 

 doctrine had a strong organismal flavor. And Darwin's 

 gemmules had an unmistakable organismal leaning in that 

 they belonged to the organism as a whole at least as much 

 as to the germ-cells. His conception was one of pan or uni- 

 versal genesis and not merely of genesis from germ-cells 

 toward soma. In fact, the main object of his quest was an 

 explanation of how body, or soma, may influence germ-cells. 



After Darwin came the next long step toward elementalist 

 reductio ad ahsurdum in Weismann's proposal to limit the 

 efficient ultimates of organization, the determinants, to the 

 germ-plasm whether this be in sex or other reproductive 

 cells ; that is, to so conceive the ultimate nature of the or- 

 ganism that there should be no reciprocal action between 

 soma and germinal elements ; that the whole movement, both 

 individual and racial, in organic evolution should be a one- 

 way movement, that way being from invisible germ to visible 

 organism. 



Finally, there has arrived the ultra-modern school, the 

 geneticists, with those wonderfully efficient instruments of 

 analysis, the factorial hypothesis of Mendelian inlieritance, 

 and the hypothesis that chromosomes are the "seat" of the 

 "factors" of heredity. These two hypotheses coupled to- 

 gether and with the hypotheses that all evolution is by mu- 

 tation, and that all mutations consist in the dropping out 

 or losing of factors and characters, need only to be pushed 

 hard enough and speculative biology will be carried to its 

 apotheosis and objective biology to its extinguishment. 



