2 INTRODUCTION [CHAP. 



to definite or indefinite results. By the term 

 'definite action' I mean an action of such a 

 nature that when many individuals of the same 

 variety are exposed during several generations 

 to any change in their physical conditions of 

 life, all, or nearly all, the individuals are 

 modified in the same manner. A new sub- 

 variety would then be produced without the 

 aid of selection." 1 



The reader will note the cause of both 

 "indefinite" and "definite" variations is attri- 

 buted to changed conditions of life. Sir E. R. 

 Lankester distinguished the former as "birth- 

 variations " " spontaneously (arising) by innate 

 variability." . . . "Nothing done to them after 

 birth . . . causes the desired characteristic [in 

 breeding]. It appears unexpectedly, almost 

 unaccountably as an inborn quality."' 



He is here alluding to what Darwin called 

 " individual differences." 3 From such, natural 

 selection is supposed to select the fittest to 

 survive. "The characteristics of a race or 

 species are maintained by natural selection, just 

 as much as they are produced by it." In these 

 words Sir E. R. Lankester is evidently not in 

 accordance with Darwin, who attributes in- 

 definite variations to the external conditions of 



1 An. and PI. under Dom., ii., p. 271. 



a " Science from an Easy Chair/' Daily Telegraph, 22nd February 

 1906. 

 3 "Origin," etc., 6th ed., p. 34. 



