ESSAYS ON BACTERIOLOGY. 109 



The dangers of vaccination, such as there are, arise 

 from four sources: 



1 . The induction of a very mild infectious disease. 



2. The transfer of human disease by the use of 

 human lymph. Of these syphilis is the most to be 

 feared. There are others, but of much less impor- 

 tance. This is avoided by the use of animal virus. 



3. The possible transfer of diseases to which the 

 animal is subject. Among these, theory, or more fre- 

 quently perhaps imagination, suggests many; facts 

 point to but few, such as erysipelas and suppuration. 

 This danger is reduced to almost nothing by proper 

 care in the management of the vaccine stables. 



4. The vaccination wound may become infected, 

 as may any other trifling abrasion. Suppuration or 

 erysipelas may supervene and cause trouble, but the 

 avoidance of these complications is so plain and sim- 

 ple, in this day of surgical cleanliness, as to hardly 

 need mention. 



There remains, perhaps, after all, a minute but real 

 danger, which, though not for a moment to be placed 

 in the balance over against the incalculable good, 

 cannot be finally ruled out till the discovery of the 

 specific bacteria of vaccination enables us to handle 

 and apply the virus with the exactness of a chemical 

 experiment. In the meantime we may rest assured, 

 and may assure the public in whose interests alone we 

 are working, that the dangers of vaccination are to- 

 day almost entirely imaginary and hardly worth more 



