NEW OUTLOOKS IN MEDICINE. 365 



yard, the dairy, and the kitchen, in certain of the arts, in the 

 normal processes of digestion, and in the maintenance in many 

 ways of the salubrity of the earth and air and water. 



The sooner we realize that the exercise of their disease-produc- 

 ing powers by the microbes as a class is only an incident in their 

 largely beneficent careers, the sooner shall we arrive at a just 

 comprehension of our newly discovered earth neighbors, upon 

 whose ministrations we are dependent for the creation and the 

 maintenance of conditions which make possible our being here 

 at all. 



The variety and complexity of the chemical transformations 

 which microbes effect in the soil and in the water are but just be- 

 coming evident. But we already know that through the vast 

 reaches of time which their life history covers the delicate work 

 which they have to do has been intricately apportioned among 

 them, and a most elaborate physiological division of labor ad- 

 justed. The struggle for existence among these lowly forms of 

 life is so keen that they are almost always confined to their legiti- 

 mate haunts and to their beneficent offices. 



I need not refer in detail to the story of the discovery, one 

 after another, of the bacteria which have been shown to cause 

 fatal maladies. Tuberculosis, cholera, pneumonia, diphtheria, 

 tetanus, anthrax, and more of the sinister brood have now yield- 

 ed the secret of their causation. 



At first the relationship of bacteria to the diseases which they 

 were found to caiise seemed quite simple. But as research went 

 on it became clear that we were still only scanning the surface. 

 It was shown that these intruding germs do not act chiefly by 

 their mere presence as foreign bodies, but more usually or more 

 fatef ully by the elaboration of subtle poisons which permeate the 

 body and destroy the cells or disturb their nice adjustment. 



So the study of the products formed and set free in the life 

 processes of these germs opened a new line of intricate and 

 delicate chemical procedure. Think of the complexity of the 

 processes which are induced in the body by the presence and ac- 

 tion of these living organisms ! We have, on the one hand, the 

 body cells, each one, small as it is, a chemical factory, setting free 

 unnumbered complex substances, some of which are to be used 

 by the body as a whole, some to be resolved into other forms, 

 some to be eliminated, since they are powerful poisons. To these 

 multiform cell units of the body enter the germs, cells too, mostly 

 plants, equally complex in their processes, also poison factories 

 sometimes of most appalling energy and grown hardy through 

 ages of strenuous battle for existence. 



Great progress has been made in research upon the agencies 

 which the body can bring into play to protect itself against these 



