INTRODUCTION 



Genetics may be defined as the science which deals with the 

 coming into being of organisms. It does not refer, however, 

 to the first creation of organic beings, but rather to the pres- 

 ent and e very-day creation of new individuals or new races. 

 It refers particularly to the part that parent organisms have 

 in bringing new organisms into being and to the influence 

 which parents exert on the characteristics of their offspring. 

 In this sense it is nearly equivalent to the term heredity. 

 But logically, though less immediately, it is concerned with 

 all agencies which in any way affect, condition, or limit the 

 coming into being of a new organism or a new race. All 

 physical and chemical changes in the world outside the organ- 

 ism, or in a word the environment, vitally concern genetics, 

 though they are the more immediate field of study of other 

 branches of biology. 



Eugenics, from its et;yTiiology, means coming into being well. 

 It is used at present solely with reference to man, and means 

 almost literally the science of being well-born. Since man is 

 zoologically merely one of the higher animals, it is evident 

 that his reproduction is a very special case falling under the 

 general laws of genetics, and before we can properly under- 

 stand this special case we must know something of the general 

 laws of genetics. We shall therefore turn our attention to 

 genetics first and foremost, and to eugenics subsequently and 

 secondarily. 



The term Eugenics was proposed by Francis Galton who 

 defines it thus: — " Eugenics is the study of agencies under 

 social control that may improve or impair the racial qualities 

 of future generations, either physically or mentally." 



As thus defined it is purely an applied science, for it is con- 

 cerned only with those agencies which are under social con- 

 trol and gives no attention to any agencies, however impor- 



