THE MOUFLON, &c 221 



very different from thofe metaphyfical and arbi- 

 trary ones, which have no exiftence but in idea. 

 Thefe phyfical genera are, in reality, compofed 

 of all the fpecies, which, by our management, 

 have been greatly vaiiegated and changed ; and, 

 as all thofe fpecies, fo differently modified by the 

 hand of man, have but one common origin in 

 Nature, the whole genus ought to conftitute but 

 a fingle fpecies. In writing, for example, the , 

 hiflory of tigers, we have admitted as many fpe- 

 cies as are really found in different parts of the 

 earth ; becaufe we are certain thut man has ne- 

 ver introduced any changes among thefe untrac- 

 eable and ferocious animals, who fubfift at pre- 

 fent in the fame manner as they were originally 

 produced by Nature. The fame remark applies 

 to all free and independent animals. But, in 

 eompofing the hiftory of oxen and fheep, we 

 have reduced all the varieties of the oxen to ene 

 ox, and all the varieties of the fheep to one fheep ; 

 becaufe it is equally certain that Man, and not 

 Nature, has produced the different kinds which 

 we have enumerated, livery thing concurs in 

 fupporting this idea, which, though clear in it» 

 felf, may not, perhaps, be fulEciently underftood. 

 That all the oxen produce together, we are af- 

 fured by the experiments of IYl.de laNux, Ment- 

 zelius, and Kalm : That all the fheep produce 

 with one another, with the mouflon, and even 

 with the goat, I know from my own experience. 

 All the varieties of oxen, therefore, form but one 



fpecies j 



