Scientific Research and Public Health 15 



istic ambitions, for in the warfare against nature we are all allies and 

 our common interests will tend to strengthen the alliance more and more 

 as we come to appreciate the nature and strength of the forces arrayed 

 against us. 



The general status of our relations with nature may be summarized 

 in this way. Man as an organism must adapt himself to his environ- 

 ment. Speaking in very general terms, the environment may be des- 

 cribed as biological and physical. Under the designation biological 

 environment I would group man's relations to other living things, 

 including his fellow man. But the living things in which we are chiefly 

 interested from the point of view of public health are those small organ- 

 isms that live on or in our bodies and which as a consequence of their 

 parasitism give rise to dangerous or fatal diseases. Some of these or- 

 ganisms, it is true, may be our friends, but for the most part they are 

 competitors and enemies — and our relations with them are best des- 

 cribed by the familiar terms of human warfare. In our operations 

 against them we must use methods both of defense and offense. The 

 notable defensive agencies are those that have been developed without 

 our conscious assistance by natural selection. They exist ready formed 

 in the body. When invading organisms gain access to our bodies they 

 are in part bodily captured and destroyed by a certain group of cells 

 designated as phagocytes, or their power for evil is met by the automatic 

 production in the tissues of antagonistic substances of various kinds 

 which immunize the body against the activity of the special invader. 

 This power of the tissues to create a special immunity is a marvelous 

 reaction in its delicacy and its complexity. The chemistry of the pro- 

 cesses involved is far beyond the ability of the scientist to understand or 

 to imitate. But we know that the power exists, a special branch of 

 preventive medicine has been organized for its study and carefully 

 trained scientific workers in many laboratories are devoting their time 

 and energy to its investigation. Nature offers here a problem of great 

 intricacy and we want to know all about it for two reasons. First, 

 simply to widen our knowledge, for Science, as Clifford put it, is interested 

 in "everything that is or has been or may be related to man". Second, 

 for a utilitarian reason. Altough the processes of immunity work 

 automatically without our conscious assistance, it is obvious that if we 

 understand them we may greatly increase their field of action. We can 

 take this defensive agency developed through the blind processes of 

 nature and improve it to who can tell what degree. A beginning has been 

 made. Everyone knows of the successful use of the antitoxins for 

 diphtheria and tetanus and of the wide spread benefits in the way of 

 prevention obtained from vaccines of various kinds. But it is only a 



