CHAPTER XVI 



Biology and medicine. Microscopic life and its relat'on to 

 human health. The role of animals in spreading disease. 

 Animal experimentation and its contributions to human 

 welfare. The new medicine, safeguarding the health of 

 the nation. 



Nowhere has the service of biology to man been so con- 

 spicuous as in the field of preventive medicine and public 

 sanitation. While the entire field of medicine is sirictly 

 speaking a biological one, yet the study of the human mech- 

 anism in health and disease holds a special place in science, 

 peculiar to itself, and it is only in so far as our knowledge 

 of plants and lower animals contributes to human health that 

 we shall consider medicine, or more properly speaking, 

 sanitation, a province of biology. 



In days gone by the doctor's chief duty was to heal the 

 sick ; today his main function is to keep men well. The 

 greatest medical progress of all time has been in the pre- 

 vention of disease. It is the knowledge of microscopic life 

 that has rendered this progress possible, a knowledge for 

 which the world is indebted to biology. 



In bacteriology no American ranks with Pasteur, Koch or 

 Jenner. Yet America has not lacked men noted in bacteri- 

 ological science, and in its practical application she ranks 

 second to none. Nowhere in all the fields of human endeavor 

 has a greater contribution to human welfare been made than 

 in the discovery of the world of unseen things about, and 

 within us, the bacteria and the Protozoa, and the recognition 

 of the part they play in causing human disease. This dis- 

 covery has revolutionized medical practice, created the new 

 science of sanitation, reclaimed vast areas formerly uninhab- 

 itable by the white race, virtually wiped out of existence 

 some of the worst scourges of mankind and saved countless 

 human beings from death and misery. This debt we owe 

 to biology. The story of this revolution would in itself fill 

 volumes, and is in its general outline so widely known that 

 its repetition here would be prosaic. And yet of common 

 knowledge how little there is that each of us can call his 



440 



