206 THE PERPETUATION OF ADAPTATIONS 



Biologists of all countries and thinking men of all walks in life 

 were drawn into the controversy. Living nature was searched 

 everywhere for evidence bearing on evolution. Habits and 

 instincts, coloration and mimicry of animals, living and fossil 

 forms were studied minutely in the search for proof, and little 

 by little, with the accumulation of facts the opponents of evolu- 

 tion were won over, until finally the conception of evolution 

 was universally accepted as the explanation of the origin of 

 modern types of living things. 



In the meantime, however, another controversy arose, this 

 time among biologists themselves who, having accepted what has 

 taken place through evolution, did not agree as to how it has 

 taken place nor in regard to the factors involved. Darwin 

 believed that natural selection, by which those organisms best 

 adapted to survive in the struggle for existence would continue 

 to live and breed, was the chief means of the maintenance of 

 diverse types, although not the only means. Some later 

 biologists believed that this process of natural selection is 

 itself the source of variations, as well as the means of perpetu- 

 ating them after adaptations had arisen, useful adaptations 

 being selected and conserved, useless adaptations, being a 

 hindrance, would lead to extinction. Still other biologists 

 could see little basis for the origin of variations on Darwin's 

 theory of natural selection, and turned back to the view advo- 

 cated by Lamarck in 1815, to the effect that animals may be- 

 come changed or adapted to conditions of their environment 

 during their individual lifetime, and then transmit such ac- 

 quired changes or adaptations to their offspring. These Neo- 

 Lamarckians thus believed in the inheritance of acquired 

 characteristics, which Darwin himself believed might play 

 some slight role in the origin of species. 



One effect, in large part, of this controversy among biologists 

 was to introduce a new method of research in biological science, 

 and experimental biology grew up. At first, animals were 

 mutilated in various ways to see if such mutilations would have 

 any effect upon the offspring. The failure of such experiments 

 was no check upon the use of the experimental method, which 



