1 



294 



VAEIATION OF PLANTS AND ANIMALS. [Ch. XXXVI. 



species still existing tliere."^' Thus the domestic dogs of the 



Amer 



Indians resemble North American 



The 



shepherd-dog 



Hun 



is very like the European wolf; 



resembles 



But although the intercrossing of several original wild stocks 



generic ; 



m some 



may have increased the total number and diversity of our 

 breeds, it cannot, says Darwin, explain the origin of such ex- 

 treme forms as thoroughbred greyhounds, bloodhounds, bull- 

 dogs, Blenheim spaniels, terriers and pugs, none of Avhich are 

 known to have been kept by savages, and which are the 

 product of breeding in civilised countries. The difference 

 in the form of the skulls in some of these races is admitted 

 by Cuvier to be sometimes more than 

 varieties there is an additional pair of molars in the upper 

 jaw ; and some, like the Turkish dogs, are deficient in the 

 number of their molars ; the mammoe also vary from seven to 

 ten in number. Dogs have properly five toes in front, and four 

 behind, but a fifth toe is often added, together with a fourth 

 cuneiform bone. Man, says Darwin, if he had cared about 

 the number of their molar teeth, mammse or digits, could, by 

 selection, have fixed these characters, in the same way as he 

 has given additional horns to certain breeds of sheep, and an 

 additional toe and feathers to the Dorkino- fowl ; but at 

 present these peculiarities have merely accompanied changes 

 in form, fleetness, size, strength, and other characters which 

 the breeder has purposely fixed. 



Inherited instincts. — It is evident that these new races 

 could not be artificially produced if the individual pecu- 

 liarities of one generation were not transmitted by inheritance 

 to the next. Even newly acquired habits and instincts are 

 often so transmitted, as was beautifully illustrated by a race 

 of dogs employed for hunting deer in the platform of Santa 



mode 



animal 



Fe, in Mexico, 

 wliicl 



and overturning it by a sudden effort, taking advantage of 

 the moment when the body of the deer rests only upon the 

 fore-legs. The weight of the animal thus thrown over is 



» Darwin ' On Yariatiou,' chap. i. p. 20. 



_» 



I 



f 



?> 





