38 HEREDITY AND ENVIRONMENT 



velopment of functions than to the develop- 

 ment of structures, and consequently it is not 

 possible to describe the former with the same 

 degree of detail as the latter. But in spite of 

 the lack of detailed knowledge regarding the 

 development of particular functions the gen- 

 eral fact of such development is well estab- 

 lished. To what extent structures may modify 

 functions or functions structures, in the course 

 of development, is a problem which has been 

 much discussed, and upon the answer to it de- 

 pends the fate of certain important theories, 

 for example Lamarckism; but this problem 

 can be solved only by thoroughgoing experi- 

 mental and analytical work. In the meantime 

 it seems safe to conclude that living structures 

 and functions are inseparable and that any- 

 thing which modifies one of these must of 

 necessity modify the other also; they are 

 merely different aspects of organization, and 

 are dealt with separately by the morphologists 

 and physiologists only as a matter of conven- 

 ience. At the same time there can be no doubt 

 that minute changes of function can frequently 

 be detected where no corresponding change of 



