104 BLASTOGENIC VAEIATIONS. 



we can at least enquire into what is known about the in- 

 fluence of nutrition on the germ-plasm as a whole. In 

 fact, we can see how far the parental plasms are indi- 

 vidually capable of being affected by changes of nutri- 

 tion, so as, on subsequent mingling in sexual union, to 

 give rise to appreciable changes in the resulting off- 

 spring. Important as this subject is, the direct experi- 

 mental evidence available upon it is distinctly meagre. 

 It is, for instance, probable that the children of a father 

 whose tissues, and therefore his sex-cells, are saturated 

 with alcohol or the products of some disease, are 

 smaller and less well formed than those of normal 

 parents, but there are no satisfactory data to support it. 

 Similar evidence with reference to the female sex- 

 cells is obviously not available, as any effects produced 

 on offspring would probably in chief part arise during 

 embryonic development, or after, and not before, fer- 

 tilisation. 



The evidence obtained as to the influence of nutri- 

 tion on the evolution of sex is only indirectly related to 

 the problem under discussion. Most of it goes to show 

 that increased feeding of young organisms tends to- 

 wards the production of a larger proportion of 

 females,* and hence, as male and female sex-cells 

 cannot be considered entirely equivalent, it follows 

 that an effect is produced on the germ-plasm. Yet 

 there is no evidence to show that the offspring of fe- 

 males which arose in spite of bad feeding differ in any 

 way from those of females produced in consequence of 

 good feeding. Nevertheless it seems probable that, as 

 nutrition has some influence in determining the sexual 

 * Vide Geddes and Thomson's " Evolution of Sex," p. 41, 1889. 



