CHAPTER XIV 



Transmission of Acquired Characters. 

 Observations and Experiments 



Experiments instituted to ascertain the hereditary transmission 

 of acquired characters. — Mutilations and disease. — Brown- 

 Sequard's guinea pigs. — The adaptation of living beings to 

 external conditions. — Variations produced in butterflies by 

 temperature and food: experiments made by Kellogg and 

 Bell, Pictet, Fisher. — Influences producing local modifica- 

 tions: facts instanced by Cunningham, Hyatt, Cattaneo. — 

 Transmission of psychical characters such as a talent for 

 music. — How acquired characters may possibly be trans- 

 mitted. — A chemical theory; the theories of A. Gautier, Le 

 Dantec and Montgomery. — The proper method to follow. 



MANY experiments have been instituted for the 

 purpose of demonstrating the heredity of 

 acquired characters and much evidence has been pre- 

 sented in support of the heredity theory. This evi- 

 dence is not of uniform value and is more or less open 

 to criticism; very little of it is convincing, probably 

 on account of the difficulties we pointed out in the 

 preceding chapter, difficulties of experimentation and, 

 above all, of interpretation. We will review the vari- 



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