TRANSMUTABLE. 125 



If he says no, then I remark that this test is 

 held by observers to be a mark of distinctness 

 of species; but all experiments prove the fertil- 

 ity of crosses between the same species or their 

 varieties, the produce of the latter breeding 

 back. 



While these sheets are passing through the 

 press, I observe the following pertinent remarks, 

 by an intelligent correspondent of "The Field," 

 for July 14th. : "Have any of your readers tried 

 to perpetuate a cross not between species but 

 varieties? If they have they will know that to 

 perpetuate to perfection is next to impossible. 

 Take, for instance, the first cross between a 

 short-horn and Alderney, and you will have an 

 animal that, in my opinion, combines the qualities 

 most desired by the dairymaid and the butcher. 

 Try and perpetuate that cross, and failure is 

 the result ; it being an established fact, that to 

 obtain a decent animal you must breed back with 

 one or other of the original stocks." Naturam 

 expelles furca, tarnen usque recurret! 



Therefore, I say that experience and experiment, 

 and the observation of such men as Mr. Knight, 

 and a host of others, are utterly opposed to the 

 possibility of the ass and the zebra, and d fortiori 

 of the ass and the horse, being descended from 

 a common parent. 



I write this with full knowledge of the facts 

 stated by Geoffrey St. Hilaire, and quoted further 

 on, because it is quite clear that that distin- 

 guished philosopher is opposed altogether to any 



