6 THE DOG IN HEALTH. 



est care in selection and rearing that is, the puppies are, 

 at a certain age, retained or rejected according to the merit 

 they display. Long before this, Nature will have weeded 

 out those that were feeble and unresisting ; in other words, 

 those perish that have insufficient stamina by a process of 

 " natural selection," as opposed to the previous kind of 

 selection by man, or " artificial selection." 



By the environment is meant the whole combination of 

 circumstances that enters into the life of the animal as 

 food, housing, exercise, climate, etc. in fact, everything 

 not implied in breeding and selection. 



Even those extremes of form seen in the gigantic St. 

 Bernard of two hundred pounds and the toy terrier of five 

 pounds are to be explained chiefly on the above principles, 

 though of course a possible origin from different wild 

 forms complicates the problem. Great as is the influence 

 of environment, greater by far are the effects of crossing 

 and selection, as every breeder of experience knows. 



The history of the different breeds of dogs is involved 

 in so much obscurity that there is little agreement on this 

 subject. But it is very doubtful if any people, savage or 

 civilized, has been without the dog, while it seems equally 

 probable that this noble animal will continue to be man's 

 companion as long as human nature endures. 



THE ZOOLOGICAL POSITION OF THE DOG. 



His Anatomy. Whether the origin of the dog be as 

 above described or not, his structure justifies placing him 

 among the carnivora. 



This is especially evident in the teeth, which are 

 adapted for seizing, tearing, and cutting rather than grind- 



