INTRODUCTION 3 



be truly scientific in the sense of being neutral, exact 

 and unbiased. Developing as it has, as a sort of 

 household necessity, and lacking the resources of 

 assured scientific data or the support of coordinated 

 methods, it is no wonder that it is even now in a 

 somewhat chaotic state. 



That a change of viewpoint will follow the present 

 liberal advance in medicine is probable. All progress 

 indicates the early formulation of a synthetic basis 

 upon which the problems of many diseases may be 

 rationally resolved. Medicine has been for a long time 

 at the parting of the ways. Like other sciences, it 

 has had to evolve through the three traditional stages 

 of development : a stage of superstition and empiri- 

 cism ; a stage of experiment and accumulation of 

 data; and a final stage of synthesis and coordination 

 of facts. That medicine is well through the second 

 stage and has entered the final stage of synthesis in 

 which practical working principles are being formu- 

 lated is evidenced especially by the increasing control 

 of infectious diseases. In many instances the older 

 volumes filled with dissertations on certain diseases 

 contain less useful information than now is comprised 

 in single sentences or words which indicate both origin 

 and control. With malaria and yellow fever explained 

 by one word, mosquito; diphtheria reduced to bacillus 

 and anti-toxin; smallpox disposed of in vaccination; 

 bubonic plague apprehended in infected vermin; and 

 synthetic chemistry producing such a specific as sal- 

 varsan; there is hope for a like conquest of the host 

 of chronic diseases, and fairer promise for a future of 

 preventive medicine. 



