( cviii ) 



balance established between environment and innate qualities 

 resulting in the production of a normal individual) to produce 

 an appreciable change, such a modification or ' difference ' 

 may be called an acquired chax^acter." * 



Such results of abnormal conditions undoubtedly supply 

 extremely striking examples of acquired characters, but it is, I 

 submit, a mistake to make too much of abnormality, or to 

 import it into a definition. Some of the most marked and 

 certainly the most easily studied and tested of acquh-ed char- 

 acters are the differences between the effects of alternative 

 environments, all of which are normal, upon the individuals of 

 a single species. The green colour of a larva of Aviphidasys 

 hetularia, if fed upon broom, is an acquired chai'acter, as is the 

 dark colour it would assume upon oak, etc. I think there- 

 fore that a more satisfactory definition of at any rate a large 

 class of acquired characters may be framed as follows : — 

 " Whenever change in the environment regularly produces 

 appreciable change in an organism, such difference may be 

 called an acquired character." 



Sir Edward Fry has objected to Mr. Galton's definition, — and 

 his objection would equally apply to that which I have sug- 

 gested above — that " the possibility of inheritance is excluded 

 by the definition, and the inquiry whether acquired characters 

 are inherited is impossible." f 



This appears to me to be only a verbal difliculty. Before 

 attempting to prove whether a certain class of characters can 

 be inherited, it is essential to be able to decide Avhether a given 

 character which it is proposed to test belongs to the class. 

 If a satisfactory criterion can be reached we can pi^oceed with 

 the test even though the name "acquired" be by our defini- 

 tion deuied to the character after transmission by inheritance. 

 The interest of the result would remain all the same. If the 

 character were there — appreciable, measurable, — the effects 

 would be incalculable in their importance, and would not be 

 diminished one iota by the consideration that the name would 

 no longer apply. Sir Edward Fry's criticism does indeed 



* Baldwin's "Dictionary of Philosophy and Psychology," p. 10. 

 t "Nature," vol. li, 1894, p. 108. See also Professor Lankester's 

 reply to the criticism, on p. 245. 



