FECUNDITY. 113 



tant influence on fecundity, through the variations in- 

 volved in the nutritive functions. 



In a preceding chapter (page 36) the relations of 

 age to fecundity have been noticed, in discussing the 

 influence of immaturity in the parents upon the de- 

 velopment of their offspring. 



It was there shown that the eggs of young animals 

 were comparatively small and few in number. 



The sow and the bitch, breeding at an early age, 

 have comparatively few young in a litter ; at the pe- 

 riod of maturity the number reaches a maximum, and, 

 at an advanced age, the number is diminished. " The 

 young hamster produces only from three to six young 

 ones, while that of a more advanced age produces 

 from eight to sixteen." x 



Similar variations in the number of young at dif- 

 ferent ages have been observed in other animals. 



The quality of food seems to exercise an influence 

 on the reproductive functions, but the data for a full 

 discussion of the subject are as yet wanting. In the 

 development of the bee, the form of the cell and the 

 character of the food determine the fertility or non- 

 fertility of the perfect insect, and it is also claimed 

 that in insects the sex is, in some cases, determined 

 by the process of nutrition. 2 



A large proportion of sugar in the food is supposed 

 to interfere with the reproductive functions. 3 



Prof. Tanner, in his paper on the reproductive 

 powers of animals, says : " The general system of diet 



1 " Principles of Biology," vol. ii., p. 438. 



2 The Popular Science Monthly, April, 1874, p. 761. 



8 Journal of the Royal Agricultural Socisty, 1865, p. 267. 



