﻿^Hamilton Xecture 



INFECTION AND RECOVERY FROM INFECTION ' 

 By SIMON FLEXNER, M. D. 



(With Five Plates) 



Mr. Secretary, Ladies and Gentlemen : I experience a peculiar 

 pleasure in being chosen to deliver the Hamilton Lecture before the 

 Smithsonian Institution, for, from its beginning, this Institution has 

 been an instrument of catholicity in science, knowing no geographical 

 or national limits and subserving no special department of learning. 

 Its object has been to promote all science. My pleasure is derived 

 from the admission of medicine, so long the healing art, into the body 

 of the exact sciences, into which it has been carried by the dis- 

 coveries in anatomy, physiology, and pathology of the last decades. 



The most notable advances that have thus far been made in the 

 medical sciences relate to the discovery of the class of infectious 

 diseases and the mode of their conquest. Infectious diseases are 

 those diseases that are caused by the entrance into and multiplication 

 within the body of minute, so-called microscopic, parasitic living- 

 beings. All animals and plants are subject to disease from this 

 source. Our theme relates to the infectious diseases of the higher 

 animals, and of man in particular, and the biological phenomena 

 involved in recovery from them. Probably the identical or closely 

 similar phenomena account for the recovery from infection of all 

 orders of living beings. 



Disease-producing parasites belong to the two great classes of 

 living things ; namely, animal and vegetable. The greater number 

 now known are vegetable in nature and are included among the 

 bacteria, but a large number also are animals and of protozoal nature. 

 Just as there are harmless and even useful protozoa that never under 

 any circumstances act as causes of disease, so there are many bac- 

 teria of similar innocuous or useful habits. 



1 Lecture delivered at Washington, D. C, February 8, 1912, under the auspices 

 of the Hamilton Fund of the Smithsonian Institution. 



Smithsonian Miscellaneous Collections, Vol. 59, No. 8 



