THE THEORIES OF IIEREOITY 71 



since there are such formidable uhjcctiuns to it as 

 Hertwig has marshalled, the only defence to be 

 offered is that Weismann's theory does nevertlieless 

 appear to be so well founded, and so fruitful in the 

 deductions to be drawn from it, that we may 

 legitimately reduce our recognition of Hertwig's 

 criticisms to something like the proportions of the 

 preceding paragraphs. If the reader likes his 

 science complete and exact he must be content to 

 ignore biology. 



CHAPTER X 



THE INHERITANCE OF ACQUIREMENTS 



Doubtless the best method of attacking the con- 

 troversial subject of this chapter is to define our 

 leadmg terms with all possible precision. 



For convenience in practice, or for purposes of 

 study, it is possible to isolate from the Whole, which 

 we call the Universe, any entity or aggregate that 

 we please and to establish an antithesis between 

 it and all else. The whole universe, save one 

 atom, or one electron, or one organism, is the en- 

 vironment, the '' milieu environnant " of that atom, 

 or electron, or organism. If we are to be philosophic, 

 we must not presume to say that only certain entities 

 or aggregates may be thus conceived. If we may 

 select an obvious entity, so to speak, such as a 

 dog, we may also select a less obvious entity such 

 as any organ, or any cell of any organ, of that 

 dog; and may regard all else, i.e. the rest of the 

 dog and all that is not that dog, as the environ- 



