H. W. Conn 363 



him the direct influences of the environment, and all sub- 

 sequently developed variations are acquired rather than con- 

 genital. They are frequently called ontogenetic variations]- which 

 is a better term than acquired, since all variations must of course 

 be acquired at some time, and the term ontogenetic indicates 

 that they are acquired by the individual and not by the germinal 

 substance. These ontogenetic variations are entirely indepen- 

 dent of those which arise in the germ plasm, since they are sup- 

 posed to affect the body simply and are perhaps not transmitted 

 by heredity. But such variations have a very great influence 

 upon the individual. From the very beginning of his life he is 

 influenced by them, and the characters that he has when adult 

 are a combination of some that he has received by inheritance 

 with some which he has developed himself as the result of the 

 action of the environment upon him. Since these latter char- 

 acters are the result of the action of the environment, they are 

 commonly adapted to it. To be sure, as elsewhere pointed out, 

 we do not understand how environment can act upon the individ- 

 ual in such a way as to produce even acquired adaptive changes 

 in it. Why a muscle grows with use or diminishes with disuse, 

 why sensations become more acute when exercised, why changes 

 in food or climate modify colors, why the shapes of leaves and 

 the length of the beaks of birds change with climate, w r e have 

 not the faintest notion. But such adaptive changes do appear 

 during the life of the individual. They form the basis of the 

 Lamarckian theories and are patent in everyday life. 



" It is impossible to determine at present to what extent the 

 characters of an adult are inherited or congenital, and to what 

 extent they are readily developed by each individual independent 

 of inheritance. When we remember what extensive changes 

 can be produced in an organism by changes in its environment, 

 and remember that the individual from the outset is acted 

 upon by the environment, it would seem to follow that its adult 

 characters must in no inconsiderable degree be simply acquired 

 rather than congenital. But it is difficult or impossible to dis- 



1 Professor Osborn's term, for which in his later writings he has substituted 

 the term modification. J. M. B. 



