HOMOLOGY AND ITS INTERPRETATION 43 



Has gone to some lost polar cell 

 And so I write this doggerel, 

 I cannot do much better." 



These kinds of variation, however, in so far as they fall 

 within the range of actual observation, are confined within 

 the limits of the organic species. Intra-specific variation, 

 however, will not suflace. To account for the adaptive modi- 

 fications superimposed upon underlying structural identity, 

 Transformism is obliged to assume the possibility of trans- 

 specific variation. Yet in none of the foregoing processes of 

 variation do we find a valid factual basis for this assumption. 



Factorial mutation, for instance, waiving its failure to 

 produce naturally-viable forms, or to meet the physiological 

 sterility test of a new species, admits of interpretation as a 

 change of loss due to the "dropping out" of a gene from the 

 germinal complex. Bateson's conception of evolution as a 

 process consisting in the gradual loss of inhibitive genes, 

 whose elimination releases suppressed potentialities, seems 

 rather incredible. Many will be inclined to see in Castle's 

 facetious epigram a reductio ad absurdum of Bateson's sug- 

 gestion; for, according to the latter's view, as the Harvard 

 professor remarks, we should have to regard man as a simplified 

 amceba. Certainly, it seems nothing short of a contradiction 

 to ascribe the progressive complication of the phenotype to a 

 simplification of the genotype by loss. 



On the other hand, not only is there no experimental evi- 

 dence of a germinal change by positive acquisition, that is, 

 by the addition of genes, but it is hard to conceive how such 

 a change could come about. "At first," admits Bateson, 

 "it may seem rank absurdity to suppose that the primordial 

 form or forms of protoplasm could have contained complexity 

 enough to produce the divers types of life." "But," he asks, 

 "is it easier to imagine that these powers could have been 

 conveyed by extrinsic addition? Of what nature could these 

 additions be? Additions of material can not surely be in 

 question. We are told that salts of iron in the soil may turn 



