PERPETUATION OF LIVING BEINGS 83 



they may appear to be to mere races or breeds, they present 

 a marked peculiarity in the reproductive process. If you 

 breed from the male and female of the same race, you of 

 course have offspring of the like kind, and if you make 

 the offspring breed together, you obtain the same result, 

 and if you breed from these again, you will still have the 

 same kind of offspring ; there is no check. But if you 

 take members of two distinct species, however similar 

 they may be to each other, and make them breed together, 

 you will find a check, with some modifications and excep- 

 tions, however, which I shall speak of presently. If you 

 cross two such species with each other, then, although 

 you may get offspring in the case of the first cross, yet, if 

 you attempt to breed from the products of that crossing, 

 which are what are called HYBRIDS that is, if you couple 

 a male and a female hybrid then the result is that in 

 ninety-nine cases out of a hundred you will get no offspring 

 at all : there will be no result whatsoever. 



The reason of this is quite obvious in some cases ; the 

 male hybrids, although possessing all the external appear- 

 ances and characteristics of perfect animals, are physio- 

 logically imperfect and deficient in the structural parts of 

 the reproductive elements necessary to generation. It is 

 said to be invariably the case with the male mule, the 

 cross between the Ass and the Mare ; and hence it is, that, 

 although crossing the Horse with the Ass is easy enough, 

 and is constantly done, as far as I am aware, if you take 

 two mules, a male and a female, and endeavour to breed 

 from them, you get no offspring whatever ; no generation 

 will take place. This is what is called the sterility of the 

 hybrids between two distinct species. 



You see that this is a very extraordinary circumstance ; 

 one does not see why it should be. The common teleo- 

 logical explanation is, that it is to prevent the impurity ol 

 the blood resulting from the crossing of one species with 

 another, but you see it does not in reality do anything of 

 the kind. There is nothing in this fact that hybrids cannot 

 breed with each other, to establish such a theory ; there 

 is nothing to prevent the Horse breeding with the Ass, or 

 the Ass with the Horse. So that this explanation breaks 

 down, as a great many explanations of this kind do, that 

 are only founded on mere assumptions. 



Thus you see that there is a great difference between 

 " mongrels/* which are crosses between distinct races, and 



