Adaptation and Health 457 



there was a rapid development of important knowledge re- 

 garding the responses of the blood and of other tissues to 

 foreign bodies, and this has given us the whole structure of 

 serum therapy and specialized diagnostic methods. The 

 researches of Metchnikoff resulted in the concept of phago- 

 cytosis, the devouring of invading microbes by the white 

 corpuscles. This is a beautiful example of the transfer of 

 the intensive study of ameba to higher and higher forms. 

 The white corpuscle is essentially an ameboid cell, an in- 

 tegral part of the more complex organism, yet continuing 

 to behave in certain respects like its primitive prototype. 

 This is not to say that the human body is *' nothing but " 

 a colony of amebas, or that the discovery as to the actual 

 facts of phagocyte behavior would not eventually have 

 been made without the evolutionary point of view. It illus- 

 trates merely a discovery that lends itself to immediate as- 

 similation into the body of evolutionary teaching. The 

 facts would not so readily fit into any of the older concepts 

 regarding the nature of man, and would probably not have 

 been so soon discovered by investigators approaching their 

 problems in one of the older ways. 



The development of antitoxin by experimental methods, 

 following shortly after the discovery of diphtheria-toxin, 

 illustrates the same thing. Man as an adaptive mechanism 

 came to be studied objectively, the specialist searching in 

 detail for each of the many mechanisms that would enable 

 him to understand better and to manage better the organism 

 as a whole. The revolution was brought about not by the 

 increased emphasis which Darwinian thought placed upon 

 adaptation, but by the new recognition of adaptation as 

 something to be understood in terms of mechanism. It is 

 not enough to marvel at the wonderful fitness of things: it 

 is necessary to find out, the evolutionsts thought, ]u%t how 

 each particular detail of fitness has come about and how 

 it operates. 



The connection between illness and perverse imps or 

 evil spirits was pretty well broken down, for at least the 



