No.fi.'U] 



INHERITANCE IN THE OSTRICH 



309 



that many now regarded as transmissible could also arise 

 as needed as direct responses. It will certainly be legit- 

 imate to question the germinal origin of those characters 

 whose formation can be interpreted as adaptive responses 

 to changes to which the organism is subject. 



The germ plasm theory of Weismann and the factorial 

 hypothesis of Mendel, Bateson and others have been of 

 inestimable value in enabling us to appreciate many of 

 the facts of heredity. But no one imagines that they give 

 us the completed account of evolution and adaptation, as 

 many are beginning to feel now that their contributions 

 can b'e estimated more or less in their entirety, and we 

 get a true perspective of what they have to offer. They 

 are and will remain important chapters in the story of 

 variation, heredity and evolution, but they are not the 

 whole volume; nor are they the concluding chapters, as 

 their supporters themselves would doubtless admit. It is 

 submitted that something is yet to be gained from con- 

 sideration of how adaptive characters arise as a result of 

 stimuli from use and disuse of parts and from environ- 

 ment, and how they may become transmissible, though 

 not necessarily germinal. The germ plasm theory to a 

 large extent and the factorial hypothesis in toto are 

 sterile when we come to questions of adaptation, and 

 natural selection lias to be freely invoked, whereas prac- 

 tically every structure in the body bears witness to its 



For an acquired character to become transmissible, so 

 that it appears independently of the stimuli which orig- 

 inally called it forth, is manifestly a difficult proceeding 

 when regarded from the point of view of the hereditary 

 structural relationships which have been established 

 through long ages. The natural and experimental 

 phenomena of regeneration show how deep is the tend- 

 ency to maintain the established relationships of the 

 various parts of the body. An acquired character repre- 

 sents some temporary disturbance of the normal rela- 

 tionships, but ordinarily the old correlations return with 

 the next generation and the new are but transient, per- 

 sisting for the generation only. When however these 



