Chap. Vlll. DEGREES OF STERILITY. 239 



believe that tlio liyl)ri(ls from Cervulus vaginalis and Rccvesii, 

 and from Pliasianus colchicus with P. toniuatus, arc perfectly 

 fertile. It has lately been asserted in France, that two such 

 distinct species as the hare and the raljbit, Avhen they can be 

 |Tot to breed together, produce offspring, which are highly fer- 

 tile when crossed with one of the parent-species. The hybrids 

 from the common and Chinese geese (A. cygnoides), species 

 which are so dillerent that they are generally ranked in dis- 

 tinct genera, have often bred in this country with either pure 

 parent, and, in one single instance, they have bred inter se. This 

 was eifected by Mr. Eyton, who raised two hybrids from the 

 same parents, but from difVerent hatches ; and from these two 

 birds he raised no less than eight hybrids (grandchildren of the 

 pure geese) from one nest. In India, however, these cross-bred 

 geese must be far more fertile ; for I am assured by two emi- 

 nently-capable judges, namely, Mr. Blyth and Captain Hutton, 

 that whole flocks of these crossed geese are kept in various 

 parts of the country ; and as they are kept for profit, where 

 neither pure parent-species exists, they must certainly be high- 

 ly or perfectly fertile. 



Tlie various races of each kind of domesticated animals are 

 quite fertile when crossed together ; yet in many cases they 

 are descended from two or more wild species. From this fact 

 wc must conclude either that the aboriginal parent-species 

 produced at first perfectly fertile hybrids, or that the hybrids 

 subsequently reared under domestication became quite fertile. 

 This latter alternative, which was first propounded by Pallas, 

 seems tlie most probable, and can, indeed, hardly be doubted. 

 It is, for instance, almost certain that our dogs are descended 

 from several wild stocks ; yet, witli perhaps the exception of 

 certain indigenous domestic dogs of South America, all are 

 quite fertile together; and anahigy makes me greatly doubt 

 whether the several aljoriginal species would at first have 

 freely bred together, and have produced quite fertile hybrids. 

 So, again, I have lately acquired decisive evidence tliat the 

 crossed offspring from the Indian humped and common cattle 

 are inter se perfectly fcrtih^; and from the observations by 

 Ililtimeyer on their important osteijlogical differences, as well 

 as from tliose by Mr. IJlytli on their differences in habits, voice, 

 constitution, etc., these two forms must be regarded as good 

 and distinct species as any in the world. According to this 

 view of the origin of many domestic animals, we must either 

 give up tlie belief of the almost universal sterility of distinct 



