138 Life and Love. 



On the other hand, the too close blood-relation- 

 ship of parents is not conducive to robust posterity, 

 and if continued may in time cause the extermina- 

 tion of the race. Horses, for instance, bred from 

 near relatives, are exceedingly delicate, and require 

 more care than those which are of mixed blood. 



In some animals near relationship produces off- 

 spring defective in some way. It would seem that 

 within prescribed limits, tlie vitality of an unrelated 

 life were necessary to the higliest good of the 

 creature, just as in flowers the best results often 

 come from fertilization from a stranger plant. 

 Nature resents any attempt to curtail that marvel- 

 lous possibility of variation which comes from the 

 union of two who are not directly connected with 

 each other. 



Because of this necessity of the species to repro- 

 duce within its own limits, there exists stabiHty of 

 form; because of the tendenc)- of the individual to 

 choose a mate not of its immediate family, there 

 exists strength and individual variety. 



Mammals, like birds, express choice in mating, 

 and some are said to take their partners for life, 

 the selection being as a rule made, not from the 

 immediate famil)-, but from among strangers. 



As a result of this tendency to choose a mate 

 from an unrelated famil}', the new life througli 

 inheritance has a boundless reservoir from which 

 to draw variability and strength, and so may find a 

 permanent place in the crowded ranks of life. 



