Chap. I. THEIR PAEENTAGE. 31 



who has closely attended to this subject, allows a difference 

 of four days in the gestation of the dog. The Rev. W. D. 

 Fox has given me three carefully recorded cases of retrievers, 

 in which the bitch was put only once to the dog ; and not 

 counting this day, but counting that of parturition, the 

 periods were fifty-nine, sixty-two, and sixty-seven days. The 

 average period is sixty-three days ; but Bellinger! states that 

 this applies only to large dogs ; and that for small races it 

 is from sixty to sixty-three days ; Mr. Eyton of Eyton, who 

 has had much experience with dogs, also informs me that 

 the time is apt to be longer with large than with small 

 dogs. 



F. Cuvier has objected that the jackal would not have been 

 domesticated on account of its offensive smell ; but savages are 

 not sensitive in this respect. The degree of odour, also, differs 

 in the different kinds of jackal f^ and Colonel H. Smith makes 

 a sectional division of the group with one character dependent 

 on not being offensive. On the other hand, dogs — for instance, 

 rough and smooth terriers — differ much in this respect ; and 

 M. Godron states that the hairless so-called Turkish dog is 

 more odoriferous than other dogs. Isidore Geoffroy ** gave to 

 a dog the same odour as that from a jackal by feeding it on raw 

 flesh. 



The belief that our dogs are descended from wolves, jackals, 

 South American Canidae, and other species, suggests a far more 

 important difficulty. These animals in their undomesticated 

 state, judging from a widely-spread analogy, would have been 

 in some degree sterile if intercrossed ; and such sterility will 

 be admitted as almost certain by all those who believe that 

 the lessened fertility of crossed forms is an infallible criterion 

 of specific distinctness. Anyhow these animals keep distinct 

 in the countries which they inhabit in common. On the 

 other hand, all domestic dogs, which are here supposed to 

 be descended from several distinct species, are, as far as is 



112) that in the Jardin des Plantes 'Hist. Nat. G^n.,' torn. iii. p. 112, on 



the period of the jackal has been the odour of" jackals. Col. Ham. Smith, 



found to be from si.xty to si.xty-three m ' Nat. Lib.,' vol. x. p. 289. 



days, exactly as with the dog. ^■» Quoted by Quatrefages in ' Bull. 



*^ See Isid. Geoffroy St.-Hilaire, Soc. d'Acclimat.,' May 11th, 1863. 



