SALMONID^E. 75 



Thus Shetland' ponies breeding together will produce Shetland 

 ponies ; and blood-horses of the Arab stock, blood-horses. 



Intermix these, and you shall have a cross-bred offspring ; which is 

 not, however, a hybrid, like the produce of a horse and an ass ; for it 

 is capable of breeding again, with its own type, or with either of the 

 parent races, or with any other pure horse. 



And so of hounds, setters, greyhounds, and all the varieties of 

 domestic dogs, so long as they are interbred among themselves ; but 

 the moment they are associated with the wolf, fox, jackal, dingo, or 

 any of the congenerous though distinct races, they will breed with them, 

 it is true, but the progeny will be truly hybrid and barren. 



If, therefore, it should be proved on experiment, that the various 

 distinct species of the Salmonidce, as they are now held to be, will, 

 when interbred, produce young capable of reproduction, it would go 

 very far to establish the fact that the distinctions are not distinctions, 

 but merely varieties. 



I must not, however, be understood as saying that the success of 

 experiments, and the establishment of such a result as I have supposed, 

 would go at all to prove that such intermixture of varieties occurred, or 

 such cross-breeds were produced, in a state of nature ; far from it. 



We know, that in vegetables, hybrids can be, and are, readily pro- 

 duced by artificial means, which will not occur once in a century, per- 

 haps never would occur at all, were the plants left to the operation of 

 nature. 



Nature abhors monstrosities ; and the proverb that the " cat will 

 follow kind" is of older wisdom than Will Shakspeare's. Man's 

 freaks have raised mongrels between the lion and the tigress; nature's, 

 so far as we know, or can conjecture, never. And always in a wild 

 state a hundred circumstances, such as different size, different habits, 

 haunts, associations, and last, not least, fear one species of the same 

 family being habitually the devourer of his relatives will prevent the 

 occurrence of such admixtures between animals. 



It would require many and strong evidences to make me believe 

 that the Brook Trout of ordinary dimensions would trust itself wil- 

 lingly within such distance of the Salmon, or Lake Trout, as would 

 permit their ova to commingle in a single furrow. 



Nor, indeed, do I believe, myself, that the result of such experi- 



