THE CAUSE OF INFECTIOUS DISEASE. 22J 



qualitative element scarcely fitted into this 

 conception. The doctrine of the causation of 

 infectious diseases is accordingly not indebted 

 to Virchow for its furtherance nearly so much 

 as are other realms of pathology. 



On the other side, those investigators who 

 were dissatisfied with Virchow's explanation 

 fell into the opposite error in their own inves- 

 tigations. The Viennese doctor Plenciz had 

 expounded very clearly and more fully than 

 any one had done before him the doctrine that 

 the cause of disease must be sought in the ex- 

 istence and activities of minute, specific living 

 things. Afterwards Eisenmann and still more 

 acutely Henle set forth this parasitic theory 

 of infectious diseases, which grew then steadily 

 stronger through the added force of important 

 discoveries. In our own time, through the 

 work of Davaine, Pasteur, Klebs, F. Cohn, J. 

 Schroter, and Koch, it has become the prevail- 

 ing theory. By his statement of this theory 

 Henle was thrown into just as sharp opposition 

 to Virchow as Koch has been recently, and at 

 that time was forced by Virchow's want of con- 

 sideration into other lines of activity, a fact that 

 enables us to understand many personalities in 

 current controversy. 



The now well-established parasitic theory 

 of disease asserts that every " specific " infec- 



