CHAPTER XI. 



THE EVIDENCE FOR THE OCCURENCE OF CROSSES 



BETWEEN INDIVIDUALS BELONGING TO DIFFERENT 



LINNEONS IN NATURE. 



Crossing of individuals belonging to different Linne- 

 ons will be brought about by opportunity or by ne- 

 cessity. 



Opportunity is offered f. i. whenever pollen gets 

 on a foreign stigma and nothing prevents its subse- 

 quent fertilizing action ; necessity is born by the sexu- 

 al desire which no animals and few men can resist in 

 the long run. 



So, while most white men in Europe would not think 

 of mating with a negress, white men not infrequently 

 do so in Africa, where no white women live, and while 

 bantamcocks don't pair with pheasants in nature, 

 they do so in captivity, if locked up with pheasant- 

 hens, in the absence of hens of their own kind. 



While hare and rabbit don't pair in nature, a male 

 hare doubtless would do so if sufficiently long isola- 

 ted with female rabbits, in the absence of male rabbits 

 on an island, as ressorts from the experiments of Mr. 

 Houwink, showing that the hare looses its inborn aver- 

 sion of a tame rabbit, if it is taken soon after birth 

 from its mother, and sucked by a tame rabbit foster- 

 mother. 



This secret for obtaining Leporids, Mr. Houwink ob- 



