192 THE HORSE 



HABIT AND USE 



When one or several limbs or organs of an animal 

 are called upon to do extra work, Nature immediately 

 tries to strengthen such members by providing extra 

 nourishment. This extra work must not be carried 

 to the point of exhaustion, or the member may become 

 weakened or diseased. 



The habit of life and the work performed play 

 important parts in producing change and variation in 

 individuals, even in so short a period as a life -time. 

 Take two brothers of nearly the same age, similar in 

 looks and characteristics, and approaching their ma- 

 jority, and let one lead an easy, sedentary life, largely 

 within doors, while the other exposes himself to the 

 sun, storms and cold, while employed in laborious toil. 

 When these brothers have reached the age of sixty, they 

 will be so unlike as to suggest that they might belong 

 to distinct races. If the fast -stepping trotter spends his 

 life in drawing heavy loads at a slow pace, and is kept 

 fat in order to secure weight, he becomes to all intents 

 and purposes a draft -horse. He may preserve his fine 

 head and his smallish feet, but in weight and movement 

 he will illustrate what marked changes are wrought in a 

 half -score of years of use. Or allow the well-bred dairy 

 cow to nurse her own calf for a half-year, so that she 

 becomes nearly dry at the end of six months, in subse- 

 quent years she will fall short of her normal production ; 

 whereas, if the calf had been removed and she had been 

 regularly milked, the flow of milk would not only have 

 been more abundant, but it would have continued much 



