6 DOGS AND ALL ABOUT THEM 



legs. Their howl becomes a business-like bark. They smell 

 at the tails of other dogs and void their urine sideways, and 

 lastly, like our domestic favourites, however refined and 

 gentlemanly in other respects, they cannot be broken of the 

 habit of rolling on carrion or on animals they have killed. 



This last habit of the domestic dog is one of the surviving 

 traits of his wild ancestry, which, like his habits of burying 

 bones or superfluous food, and of turning round and round on 

 a carpet as if to make a nest for himself before lying down, 

 go far towards connecting him in direct relationship with 

 the wolf and the jackal. 



The great multitude of different breeds of the dog and the 

 vast differences in their size, points, and general appearance 

 are facts which make it difficult to believe that they could 

 have had a common ancestry. One thinks of the difference 

 between the Mastiff and the Japanese Spaniel, the Deerhound 

 and the fashionable Pomeranian, the St. Bernard and the 

 Miniature Black and Tan Terrier, and is perplexed in con- 

 templating the possibility of their having descended from a 

 common progenitor. Yet the disparity is no greater than 

 that between the Shire horse and the Shetland pony, the 

 Shorthorn and the Kerry cattle, or the Patagonian and the 

 Pygmy ; and all dog breeders know how easy it is to produce 

 a variety in type and size by studied selection. 



In order properly to understand this question it is necessary 

 first to consider the identity of structure in the wolf and the 

 dog. This identity of structure may best be studied in a 

 comparison of the osseous system, or skeletons, of the two 

 animals, which so closely resemble each other that their 

 transposition would not easily be detected. 



The spine of the dog consists of seven vertebrae in the neck, 

 thirteen in the back, seven in the loins, three sacral vertebrae, 

 and twenty to twenty-two in the tail. In both the dog and 

 the wolf there are thirteen pairs of ribs, nine true and four 

 false. Each has forty-two teeth. They both have five front 

 and four hind toes, while outwardly the common wolf has 



