274 APPENDIX D 



that many are subject to the law of ' recession 

 towards mediocrity '. He considered that evolu- 

 tion proceeds by the selection of large variations 

 (saltation) as well as of small. He suggested 

 that certain variations do not obey the law of 

 recession, but are the expression of a sudden leap 

 to a new position of genetic stability. He thus 

 anticipated de Vries in both ' Fluctuations ' and 

 * Mutations ', proposing for the latter type of 

 variation the far better and far more descriptive 

 term * transilient '. 



The conclusion that evolution has been 'dis- 

 continuous', proceeding by means of relatively 

 large steps, was urged with much vigour by 

 Professor Bateson in his work On Variation (1894). 

 It was in a review of this book that Galton pro- 

 posed the term 'transilient', although the opinion 

 that evolution may take place by large steps 

 had been expressed by him at a much earlier 

 date. 



AUGUST WEISMANN revealed the unsubstantial 

 nature of the evidence on which the hereditary 

 transmission of acquired characters l was believed. 



1 It may be convenient to quote three passages from the author's 

 Essays on Evolution (1908) : 



(1) 'For the question 'Are acquired characters hereditary?' 

 it would be more accurate to substitute ' Can the acquired char- 

 acters of the parent be handed down as inherent characters in the 

 offspring ? ' ' (p. 144). 



(2) ' It is in no way necessary that the acquired elements of a char- 

 acter should be disentangled from the inherent elements, if only we 

 can prove that the character as a whole is dependent upon a con- 

 trollable external cause, and is therefore itself controllable. In 

 fact we speak of a character as ' acquired ' just as we speak of an 

 article as 'manufactured', although the result itself is a complex 



