IV. CONTROVERSIAL QUESTIONS. 



§ 15. ACQUIRED CHARACTERS AND VARIATIONS 

 CAUSED BY NUTRITION. 



It is not my intention to enter into a discussion of 

 the much disputed question of the inheritance of acquired 

 characters. I only wish to show how a clear understand- 

 ing of the difference between the theory of selection and 

 the theory of mutation to a great extent simplifies, and 

 may perhaps even lead to a satisfactory solution of, this 

 problem. 



The point at issue is really one of definition. Each 

 author's conclusion on this question depends on the defi- 

 nition of "acquired" with which he starts. 



Starting as we can, after the discussion in the last 

 chapter, with an insight into the nature of selection and 

 of improved races, let us formulate as clearly as possible 

 what the question for decision really is. 



Mutations obviously do not fall within the category 

 of acquired characters. There can, it seems to me, be 

 no doubt about this. They appear suddenly ; w^e can as 

 yet assign no cause for them ; they seem independent of 

 the environment. They are germinal variations in the 

 strictest sense of the term. 



According to the mutation hypothesis species have 

 arisen by such mutations. Therefore specific characters 

 are never "acquired"; and there is therefore no need for 



