4 ' GENETICS AND EUGENICS 



tant, which are not under social control. Its scope therefore 

 is much narrower than that of genetics. It is concerned with 

 only so much of genetics as concerns man, and with only so 

 much of that as is under social control. To determine what 

 are the general principles of genetics and to what extent man 

 is subject to them are primarily biological problems, but to 

 determine how far these are socially controllable is a problem 

 for the sociologist, and one which I shall not attempt to 

 answer without help from sociologists. 



The coming into being of a new organism is one of the 

 least understood of all natural phenomena. Even to the 

 trained biologist it is largely an unexplained mystery. To 

 understand his vie^'point concerning it, and what definite 

 facts he knows about it, and how he attempts to explain 

 them, we must be familiar with certain of the generalizations 

 of biology. Familiarity with the more important of these 

 fundamental generalizations of biology will be assumed in the 

 present work. 



From the philosophical standpoint genetics is only a sub- 

 division of evolution. For the evolution theory teaches that 

 the organisms now existing have come into being through 

 descent with modification from those which existed at an 

 earlier time and, in general, that the world as we know it today 

 is different from what it has been at any previous time; that 

 all things, organic and inorganic, are constantly undergoing 

 change, yet nothing wholly new comes into being, for every- 

 thing new arises out of something which existed before. Thus 

 no new matter is created, yet new creations constantly arise 

 out of elements which before existed in different form. 



It will be our first task to discuss the rise of the evolution 

 theory and in particular its relation to the subject of genetics. 

 Subsequently we shall discuss the known facts of genetics and 

 the several ways in which biologists interpret them; and 

 finally we shall discuss human evolution as a subdivision of 

 genetics, and its social control, or eugenics. 



