THE EVOLUTION OF LIVING BEINGS. 121 



tained from a poacher and it worked so splendidly 

 that he is now in the possession of a fine fullgrown F 2 

 generation of Leporids, a male of which has already 

 paired with one of its sisters. a ) 



I would therefore not be a bit surprised if it were 

 subsequently proved that our tame rabbits were evol- 

 ved from an original cross between the wild rabbit 

 and the hare, which cross Mr. Houwink is trying to 

 obtain in a similar way. 



Perhaps this trick of having the individuals belon- 

 ging to a foreign Linneon nurtured by an individual 

 belonging to the Linneon, with which one desires to 

 cross them, is very widely applicable and may lead 

 to the obtention of many interesting hybrids. 



Dr. van Oort tells me that it is well known, that a 

 bitch of our domestic dogs refuses nearly always to 

 mate with a male wolf, but shows no aversion if she 

 herself was raised by a female wolf. 



The aversion to mating between individuals belon- 

 ging to different Linneons can consequently be overco- 

 me, and that this happens in nature also, is proved by 

 the fact that Linneons which intercross in nature are 

 known from almost all groups of animals and plants. 

 Of animals we will mention of the class of the Echino- 

 dermata: Echinus esculentus and E. acutus in the 

 neighbourhood of Plymouth (cf. Shearer, de Morgan 

 and Fuchs Phil. Frans act. Royal Society B 204 pp.- 

 2 55 — 362), of the Class of the Vermes : hybrids between 

 Ascaris univalens and A. bivalens with three chromoso- 



*) This copulation has since proved to be fertile, but the young 

 ones died soon after birth. 



