HISTORIC DEVELOPMENT OF IMMUNOLOGY 17 



recognized as the specific treatment for diph- 

 theria. 



THE TWENTIETH CENTURY 



The most noticeable thing about twentieth 

 century medicine is the growth of cooperation 

 and the fact that nearly every important ad- 

 vance that has been made is prophylactic that 

 is, comes within the scope of preventing the oc- 

 currence, the recurrence, or the spread of dis- 

 ease. The tendency in all branches of recent 

 sciences, even in zoology, sociology, therapeu- 

 tics, internal medicine, and surgery, has been 

 to pass out of the descriptive into the experi- 

 mental stage. Loeb (1859-), who is now head 

 of the Department of Experimental Biology in 

 the Eockefeller Institute, has been a brilliant 

 investigator in many branches of physiology. 

 Ehrlich (1854-) has done the most effective 

 work since Pasteur and Koch in the science of 

 infectious diseases, and he has added new ter- 

 ritory to the domain of experimental pharma- 

 cology and therapeutics by his genius for re- 

 search and his wonderful industry. 



In 1903, Wright and Douglas first determined 

 the direct dependence of phagocytosis upon 

 some ingredient of the blood-serum; and they 



