22 Introduction 



Plencig, of Vienna, became convinced that there was an undoubted 

 connection between the microscopic animalcules exhibited by the 

 microscope and the origin of disease, and advanced this opinion as 

 early as 1762. 



In 1704 John Colbach described "a new and secret method of 

 treating wounds by which healing took place quickly, without 

 inflammation or suppuration." 



Boehm succeeded in 1838 in demonstrating the occurrence of 

 yeast plants in the stools of cholera, and conjectured that the 

 process of fermentation was concerned in the causation of that 

 disease. 



In 1840 Henle considered all the evidence that had been collected, 

 and concluded that the cause of the infectious diseases was to be 

 sought for in minute living organisms or fungi. He may be looked 

 upon as the real propounder of the Germ Theory of Disease, for 

 he not only collected facts and expressed opinions, but also investi- 

 gated the subject ably. The requirements which he formulated in 

 order that the theory might be proved were so severe that he was 

 never able to attain to them with the crude methods at his disposal. 

 They were so ably elaborated, however, that in after years they were 

 again postulated by Koch, and it is only by strict conformity with 

 them that the definite relationship between micro-organisms and 

 disease has been determined. 



Briefly summarized, these requirements are as follows: 



1. A specific micro-organism must be constantly associated with 

 the disease. 



2. It must be isolated and studied apart from the disease. 



3. When introduced into healthy animals it must produce the 

 disease, and in the animal in which the disease has been experiment- 

 ally produced the organism must be found under the original 

 conditions. 



In 1843 Dr. Oliver Wendell Holmes wrote a paper upon the 

 "Contagiousness of Puerperal Fever." 



In 1847 Semmelweiss, of Vienna, struck by the similarity between 

 fatal wound infection with pyemia and puerperal fever, cast aside 

 the popular theory that the latter affection was caused by the 

 absorption into the blood of milk from the breasts, and announced 

 his belief that the disease depended upon poisons carried by the 

 fingers of physicians and students from the dissecting room to the 

 woman in child-bed, and recommended washing the hands of the 

 accoucheur with chlorin or chlorid of Hme, in addition to the use 

 of soap and water. He was laughed to scorn for his pains. 



In 1849 J- K. Mitchell, in a brief work upon the " Cryptogamous 

 Origin of Malarious and Epidemic Fevers," foreshadowed the germ 

 theory of disease by collecting a large amount of evidence to show 

 that malarial fevers were due to infection by fungi. 



Pollender (1849) and Davaine (1850) succeeded in demonstrating 



