FECUNDITY. HI 



The greater fecundity of domesticated varieties, 

 as compared with that of wild species, is, in great 

 measure, owing to a better supply of food throughout 

 the year, and the more uniform conditions in which 

 they are placed. 



The activity of the reproductive organs is neces- 

 sarily dependent upon the function of nutrition which 

 supplies the materials concerned in its operations. 



Dr. Carpenter says, " There is a certain degree of 

 antagonism between the nutritive and the generative 

 functions, the one set being executed at the expense 

 of the other." ' 



A certain activity of the nutritive functions is re- 

 quired to secure the greatest fertility in both plants 

 and animals. When the function of nutrition is im- 

 paired by disease, or when the supply of food is not 

 sufficient for the wants of the system, the reproduc- 

 tive powers suffer a corresponding decrease in their 

 activity. 



Sheep bred on rich pastures are more likely to 

 produce twin lambs than those gaining a scanty sub- 

 sistence in less favored localities. 



It is said that, "among the barren hills of the 

 west of Scotland, two lambs will be borne by about 

 one ewe in twenty, whereas in England something 

 like one ewe in three will bear two lambs." a 



While full feeding seems to increase the fecundity 

 of varieties, any excess in the nutritive activity of the 

 system will as readily impair the powers of reproduc- 

 tion. 



1 "Comparative Thysiology," p. 147. 



2 "Principles of Biology," vol. ii., p. 469. 



