LECTURE LXXVIII. 



THE INFLUENCE OF HEREDITY AND PREPOTENCY. 



One of the most commonly accepted laws in animal breed- 

 ing is that "like produces like." This simply means the in- 

 heritance by the offspring of the characteristics of the parents 

 at the time of procreation. Although there are many excep- 

 tions to this law, an examination of the facts will reveal that 

 this law is always in operation, also that it extends to every 

 feature of the organism. While in some instances it may 

 not show up very strongly, this is simply due to the fact that 

 some other law which is more predominant for the time be- 

 ing has obscured it. 



The resemblance of the offspring to the parent is very 

 marked in most cases. This is simply the influence of the 

 law of heredity. It is very helpful and valuable in the breed- 

 ing of our best animals. By means of this apparently simple 

 law we are able to breed definite types for definite purposes. 

 It is the outward guide. -Its influence in animal breeding is 

 not confined solely to the external conformation, color mark- 

 ings, and so on. It shows its influence on the nervous sys- 

 tem, internal organs and, in fact, in every detail of the animal 

 organism. This being the case, it is sometimes a very dan- 

 gerous law. Through it, either directly or indirectly, many 

 of the very worst kinds of diseases are transmitted. 



In discussing this law it might be well to illustrate the in- 

 fluence of the same by use of a few of the most common 

 and marked examples. The uniformity found in the different 

 breeds of our domestic animals is a very good example. In 

 almost every breed there are favorite families or strains 

 which are noted and valued because through the law of 

 heredity these characteristics can be readily transmitted to 

 the offspring. 



The Down sheep, for instance, will invariably transmit their 

 dark face and leg color markings as well as their mutton 

 form to their progeny. 



The ability of the cow to convert large quantities of feed 



