266 APPENDIX D 



Fluctuations are, according to de Vries, unable, 

 however rigidly and however long selected, to 

 lead to progressive evolution. The following 

 passages in which this belief is expressed, assert 

 perfectly clearly that these limitations rashly 

 assumed to be permanent are revealed by means 

 of heredity. They also plainly show that de 

 Vries, in maintaining the uselessness of 'fluctua- 

 tions ' as the material for progressive evolution, is 

 merely availing himself of a principle established 

 much earlier and on far firmer grounds by 

 Francis Galton the well-known principle of 

 ' recession towards mediocrity ' : 



(3) ' Fluctuations always oscillate round an average, and 

 if removed from this for some time, they show a tendency 

 to return to it. This tendency, called retrogression, has 

 never been observed to fail, as it should, in order to free the 

 new strain from the links with the average, while new 

 species and new varieties are seen to be quite free from 

 their ancestors and not linked to them by intermediates.' ' 



In the following passage, as well as in (5), 

 de Vries is of course referring to * fluctuations ' : 



(4) ' . . . Long-continued selection has absolutely no 

 appreciable effect. Of course I do not deny the splendid 

 results of selection during the first few years, nor the 

 necessity of continued selection to keep the improved races 

 to the height of their ameliorated qualities. I only wish 

 to state that the work of selection here finds its limit and 

 that centuries and perhaps geologic periods of continued 

 effort in the same direction are not capable of adding any- 

 thing more to the initial effect' 2 



1 Species and Varieties, 18. Ibid., 790-1. 



