136 



Life and Love. 



XV. 



I 



VARIABILITY AND INHERITANCE. 



N all life, both low and high, the power to re- 

 produce depends upon a certain resemblance 

 between the two parents. Sex 

 attraction is operative only 

 within narrow limits. 



Long ago, we are told, there 

 existed strange creatures on 

 the earth. There were then no birds 

 such as now live, and no mammals. 



Reptiles and birds were not yet 

 separated from each other, but there 

 existed creatures which were a sort of 

 mixture of both. In course of time 

 the descendants of these 

 strange reptile-birds became 

 more decidedly rcptilc-like on the one hand, and 

 bird-like on the other. 



In early ages all life seems to have found it 

 easier to take new forms than it does now, and so 

 there arose the race of reptiles as a result of cher- 

 ishing the most reptilian characteristics of the 

 reptile-bird form, and developing these character- 

 istics to the exclusion of others. 



