368 Problems of Organic Adaptation 



evolution and adaptation what he calls "proenvironment" ; 

 this he defines as "the capacity of any organism for perceiv- 

 ing and then positively growing or moving toward an envi- 

 ronment that is the most satisfying for it." This capacity 

 he holds is present in all living things and has its analogue 

 even in chemical affinity. Certainly when one observes how 

 almost universally organisms distinguish between benefi- 

 cial and injurious environments, one is compelled to admit 

 that some such capacity must be present in all living things, 

 and that it must be an important factor in the adaptive or 

 beneficial responses of organisms. Whether it is also a 

 factor in the evolution of racial adaptations depends upon 

 the answer to the question whether such individual or ac- 

 quired adaptations can become hereditary. Macfarlane 

 takes it for granted that they can be, and he would probably 

 maintain, though he has not developed this thesis specifi- 

 cally, that all inherited adaptations were in their individual 

 origins beneficial or satisfying responses to the environment. 

 Against this view may be urged all the weighty objections 

 to the doctrine of the inheritance of acquired adaptations 

 which are familiar to all biologists. It is difficult if not im- 

 possible to explain on this ground the origin of numerous 

 inherited adaptations which are for the good of the species 

 only and are destructive of the individual; for example, 

 the peculiar structures, functions, and instincts of worker 

 and drone bees, which lead to the sacrifice of the indi- 

 vidual for the good of the colony, cannot be explained by 

 any form of Lamarckism, but are readily explained by 

 Darwinism. 



According to the Darwinian theory, the guiding and 

 directing power of selection should be directly proportional 

 to its severity. If it eliminates only those mutants that are 

 positively injurious or non-viable, as many adherents of the 



