VIII. NUTRITION AND SELECTION OF SEMI- 

 LATENT CHARACTERS. 



§ 26. INCREASED NUTRITION FAVORS THE DEVELOP- 

 MENT OF THE ANOxMALY. 



Fluctuating variability is a phenomenon of nutrition, 

 whereas mutability is the result of hitherto unknown 

 causes (Vol. I, p. 575). This statement, which is per- 

 haps the sharpest expression of the contrast between 

 fluctuating or continuous variability on the one hand 

 and occasional sudden transitions from one species into 

 another on the other, has been discussed more than once 

 in this work. It is equally true for the variability oi 

 semi-latent characters as for that of normal ones. This 

 side of the statement has also been already alluded to. 

 and I have cited many instances in order to prove its 

 truth. Everywhere nutrition and variability are so in- 

 timately connected that the physiology of the latter ])hc- 

 nomenon can hardly be dealt with without discussing 

 its relation to the former. 



Artificial selection is the choice of the better nour- 

 ished individuals, except of course, when selection is 

 carried out in the negative direction (Vol. I, p. 142). 

 In the first volume I cited as a proof of this generaliza- 

 tion an experiment with a semi-latent character. The 

 number of accessory carpels of Papai'cr sonniifcniin 

 polyccpliahiin was shown to be dependent on selection 



