SELECTION 193 



longer and the normal flow of milk have been main- 

 tained the following year. The family horse, overfed 

 and tinder-used, soon becomes slow and logy, although 

 at first he was spirited and active. 



It can be readily understood that, in order to pre- 

 serve the inherited characteristics of a breed or an 

 individual, the animals must not only be placed under 

 similar conditions as to food and climate, but must 

 retain similar habits and do similar work to that per- 

 formed by the ancestors from which they sprung. 



It is difficult to discover certainly the character of the 

 ancestors by an inspection of an animal; it is easy to 

 determine the uses to which they have been put and 

 the abuses which they have suffered. Full use, without 

 abuse, and appropriate work tend to produce variation 

 for the better and to preserve and increase the efficiency 

 of specialized qualities, as well as to make them perma- 

 nent in time and capable of being transmitted to suc- 

 ceeding generations. 



SELECTION 



It is self-evident that variation is constantly taking 

 place, sometimes for the better, sometimes for the 

 worse, and that changes sometimes appear which do not 

 affect intrinsic value. Most of the causes which produce 

 variation are known, but the causes may not produce 

 immediate noticeable changes. It may take several 

 generations before the accumulated effects become 

 marked. The careless breeder does not note these 

 causes and their effects until degeneracy has gone so 

 far as to make it advisable to introduce new blood, 



M 



