342 HEREDITY AND ENVIRONMENT 



a part is a function of its position." We now 

 know that this expresses only a fraction of the 

 truth. The fate of a part is primarily a func- 

 tion of its organization and only secondarily a 

 function of its position. 



These are only a few illustrations of the 

 many kinds of abnormal development which 

 may be caused by changed environment or by 

 unusual functional activities. At all stages of 

 ontogeny the course of development may be 

 altered by extrinsic stimuli but earlier stages 

 may be more profoundly influenced than later 

 ones. 



D. INHERITANCE OR NON-INHERITANCE 

 OF ACQUIRED CHARACTERS 



Few questions in biology have been dis- 

 cussed so fully and so fruitlessly as this. It is 

 a problem of the greatest interest not only to 

 students of biology but also to sociologists, 

 educators and philanthropists and yet it is still 

 to a certain extent an unsolved problem. It is 

 well known that Lamarck taught that charac- 

 ters due to desire or need, use or disuse, and to 

 changed environment or conditions of life were 



