HEREDITY AND VARIATION 261 



improved the various types of horses familiar to us as draft horses, 

 coach horses, hackneys, and the trotters. 



It is needless to say that all the various domesticated animals 

 have been tremendously changed in a similar manner since civilized 

 man has come to live on the earth. When we realize the very 

 great amount of money invested in domesticated animals; that 

 there are over 60,000,000 each of sheep, cattle, and swine and 

 over 20,000,000 horses owned in this country, then we may see 

 how very important a part the domestic animals play in our lives. 



Improvement of Man. If the stock of domesticated animals 

 can be improved, it is not unfair to ask if the health and vigor 

 of the future generations of men and women on the earth might 

 not be improved by applying to them the laws of selection. This 

 improvement of the future race has a number of factors in which 

 we as individuals may play a part. These are personal hygiene, 

 selection of healthy mates, and the betterment of the environment. 



Personal Hygiene. In the first place, good health is the one 

 greatest asset in life. We may be born with a poor bodily machine, 

 but if we learn to recognize its defects and care for it properly, 

 we may make it do its required work effectively. If certain muscles 

 are poorly developed, then by proper exercise we may make them 

 stronger. If our eyes have some defect, we can have it remedied 

 by wearing glasses. If certain drugs or alcohol lower the efficiency 

 of the machine, we can avoid their use. With proper care a poorly 

 developed body may be improved and do effective work. 



Eugenics. When people marry there are certain things that 

 the individual as well as the race should demand. The most 

 important of these is freedom from germ diseases which might be 

 handed down to the offspring. Tuberculosis, that dread white 

 plague which is still responsible for almost one seventh of all 

 deaths, epilepsy, and feeble-mindedness are handicaps which it 

 is not only unfair but criminal to hand down to posterity. The 

 science of being well born is called eugenics. 



The Jukes. Studies have been made on a number of different 

 families in this country, in which mental and moral defects were 

 present in one or both of the original parents. The "Jukes " 

 family is a notorious example. The first mother is known as 



