34 2 Problems of Organic Adaptation 



tion is a theory of transmutation which undertakes to ex- 

 plain the diversities which exist in the living world, but not 

 the original properties of life. It undertakes to explain the 

 various forms of adaptation found among organisms, but 

 not organic adaptability. It may be that regulation or 

 regeneration is one of the fundamental physiological prop- 

 erties of living things, and that it belongs in the same cate- 

 gory with assimilation, growth, metabolism, reproduction, 

 and irritability properties which are found in the lowest 

 organisms as well as the highest, and which can therefore 

 be left out of the list of things which organic evolution may 

 reasonably be expected to explain. But this would certainly 

 not apply to peculiar, individual adaptations such as have 

 been named. The origin of these must be explained no less 

 than the origin of particular racial adaptations. Moreover, 

 it is incredible that things so much alike as racial and indi- 

 vidual adaptations should be due to wholly different causes. 

 It seems, therefore, that while natural selection is a fairly 

 satisfactory explanation of racial adaptations, it does not, 

 in the form proposed by Darwin, furnish a satisfactory ex- 

 planation of individual adaptations, and this has led several 

 biologists, notably Wolff and Driesch, to the conclusion that 

 Darwinism "fails all along the line," while many who are not 

 biologists have hailed with joy what they regard as the 

 "death of Darwinism." But this conclusion is certainly un- 

 warranted and extreme. There are many racial adaptations, 

 as we have seen, which are beautifully explained by the 

 Darwinian theory, and it is certainly premature to abandon 

 hope of explaining individual adaptations by a similar prin- 

 ciple. 



5. Intra-personal Selection 



Weismann recognized that natural selection as set forth 

 by Darwin was not a satisfactory explanation of all phe- 



