262 APPENDIX D 



mission of acquired characters with a levity justly 

 rebuked by Mr. R. H. Lock in the following 



' . . . de Vries believes that individual variability de- 

 pends entirely upon nutrition ; but under this head he 

 includes practically the whole environment of plants 

 light, space, soil, moisture, and the like. Characters ac- 

 quired in a similar way by previous generations are inherited, 

 and the effect of conditions upon the developing seed whilst 

 still borne upon the parent plant may be considerable. 

 Thus easily does de Vries dispose of the puzzling question 

 of the inheritance or non-inheritance of acquired characters. 

 Acquired characters are inherited ; they are not of any 

 importance in the origin of species.' 1 



It will now be well to show from several 

 passages that de Vries considers ' fluctuations ' to 

 be hereditary, and that the limits which he 

 assigns to them only become manifest by means 

 of heredity. 



' . . . we must,' says Mr. Punnett, ' recognise 

 with de Vries the type of variation which he has 

 termed fluctuating.' 2 In order to ensure an 

 accurate recognition it will be safest to quote 

 de Vries's words. 



(1) In the celebrated Mutationstheorie (Leipzig, 

 1901, I.) de Vries states that, in advocating the 

 use of the term ' fluctuation ', he is merely adopt- 

 ing a word often used by Darwin himself. Thus, 



1 Variation, Heredity and Evolution, London, 1909, 2nd Ed., 

 155. See also passage (1) quoted from Mr. Lock on p. 270. 



2 Mendelism, R. C. Punnett, 2nd Ed., Cambr. (1907), 70. 



3 An example ofDarwin's use of the words 'fluctuating variability ' 

 is to be found in the following passage from a deeply interesting 



