

110 



DOMESTICATION ELIMINATES STERILITY. 



Chap. XVI. 



experiment would in all cases be surrounded by many diffi- 

 culties. Dureau de la Malle, who has so closely studied classical 

 literature, states 27 that in the time of the Komans the common 

 mule was produced with more difficulty than at the present 

 day ; but whether this statement may be trusted I know not. A 

 much more important, though somewhat different, case is given 

 by M. Groenland, 28 namely, that plants, known from their inter- 

 mediate character and sterility to be hybrids between iEgilops 

 and wheat, have perpetuated themselves under culture since 

 1857, with a rapid but varying increase of fertility in each genera- 

 tion. In the fourth generation the plants, still retaining their 

 intermediate character, had. become as fertile as common 

 cultivated wheat. 



The indirect evidence in favour of the Pallasian doctri 



me 



appears to me to be extremely 



In the earlier chapt 



I have attempted to show that our various breeds of dogs 



ended from 



al wild species; and 



case with sheep. Thei 



can 



no long 



b 



probably is the 

 any doubt that 



the Zebu or humped Indian ox belongs to a distinct species 

 European cattle : the latter, moreover, are descended from 

 or three forms, which may be called either species or wild r 

 but Avhich co-existed in a state of nature and kept distinct, 

 have good evidence that our domesticated pigs belong t 

 least two ; 



' 



t. We 

 j to at 

 pecific types, S. serofa and Indicus, which probably 

 ved together in a wild state in South-eastern Europe. Now, a 

 idely-extencled analogy leads to the belief that if these several 



allied species, in 



bee 



wild state or wdien first reclaimed, had 



their first 



unions 



crossed, they would have exhibited, both in their 

 and in their hybrid offspring, some degree of sterility 



Nevertheless the several domesticated races descended from 

 them are now all, as far as can be ascertained, perfectly fertile 

 together. If this reasoning be trustworthy, and it is apparently 

 sound, we must admit the Pallasian doctrine that long-continued 

 domestication tends to eliminate that sterility which is natural 

 to species when crossed in their aboriginal state. 



2 7 ' Annales cles Sc. Nat.,' torn. xxi. (1st series), p. 61. 



28 < Bull. Bot. Soc. de France,' Dec. 27th, 1861, torn. viii. p. 612 



