422 ANIMAL BIOLOGY 



have seen, biologists the world over are developing and applying 

 these principles in plant and animal breeding. What was impossible 

 a few years ago is now being accomplished almost as a mere matter 

 of routine work in many biological laboratories. 



Important as the application of these principles is in the mastery 

 of agricultural problems, a far more profound power remains to be 

 realized when, as nations, mankind becomes awake to the fact that 

 these same basic principles apply equally to human inheritance. 

 If it be true that the human race has not improved in bodily and 

 mental characteristics since the time of the ancient Greeks, the 

 responsibility rests with Man himself. He has studied and applied 

 selective breeding of animals and plants. He has in general kept 

 the best for his purposes that nature offered and eliminated the 

 rest. He has depended chiefly on the stock and only secondarily 

 on the environment for permanent improvement. But it has been 

 otherwise with himself. Much of the worst human stock has 

 continued to survive and multiply, and disproportionately so as 

 civilization has advanced. Reliance has been placed almost solely 

 on the improvement of the conditions of life and not on breeding 

 from the best. We may fairly say that humanity is what it is to- 

 day in spite of the continual violation of many of the biological 

 principles which would improve the race. (Figs. 179, 269.) 



This, of course, is merely a statement of fact: not a reproach. 

 Man could not have done otherwise until it had been demonstrated 

 by biological investigation that he is a part of, and not apart from 

 the rest of living nature — the most profoundly important fact that 

 biology has contributed to human welfare. With this fully grasped, 

 new import is given to the study of general biological principles and 

 no plant or animal is too insignificant to throw light on life prob- 

 lems. And this has been the chief source of the stupendous po- 

 tential for biological control which has within less than a century 

 come to mankind. Potential for control, we say, because years of 

 research by generations of investigators is still necessary before 

 we shall be prepared to solve the problems we now face and which 

 the saturation point of human population will immensely augment. 

 (Figs. 188, 194, 270, 271.) 



The natural method of securing a healthy — adapted — race is, 

 of course, the gradual process of adjustment throughout the ages by 

 response to environmental stimuli. But mankind has the power, 



