INFECTIOX. 101 



man beings, but animals and their products. This restrictive, pre- 

 ventive medicine, if we may be allowed the term, has been rewarded 

 by the grandest results, though it at first paid little or no attention 

 to the primary causes of the diseases it sought to prevent. The 

 causes it recoy:nized were those of intercourse and commerce. It 

 sought to regulate these with reference to the contagious diseases, 

 and the result has been that the black-death and bubo-pest have 

 become entire strangers to Western Europe ; Asiatic cholera is no 

 longer the terror of the civilized world. Aside from the benefits of 

 vaccination, the varioliB no more carry horror into the human family. 

 The cattle-owner of Europe does not awaken on any morning and 

 find the rinderpest devastating his herd. The lung-plague of cattle 

 is kept within restricted limits, and so of other diseases of like na- 

 ture. 



Tliese remarks have no relation to diseases of a purely malarial 

 character, which are based on locality. Here we have to do with 

 questions of drainage, tillage, and the like, which we will not dis- 

 cuss at present. 



"While this work of modern medicine is of no secondary impor- 

 tance, the results of the observations and experiments of recent 

 years have opened still another path to the workers in preventive 

 medicine. 



They have discovered the causes of some diseases, and gained 

 knowledge that justifies us in assuming that the causes of all infec- 

 tious and contagious diseases are of a similar nature. This cause 

 is the schizomycetes or fission-fungi, and their germs, which bear 

 the general name of micrococci or microbes. 



Having discovered these objects, the next step has been to study 

 their mode of life, how they live and multiply, what elements favor 

 these processes, and what are opposed to them. 



Our conceptions in this regard are still far from clear, and too 

 frecpiently our action is based on mistaken reasoning. 



We too often think that, when we have removed the odor from 

 an offensive place or substance, we have destroyed its disease-pro- 

 ducing qualities, a hope which is only too soon negatived by expe- 

 rience. 



The resistibility of germs is such that we may look upon it as 

 very nearly fallacious to disinfect the atmosphere by adding to it 

 chlurine-gas, or sulphur, or any similar disinfectants. Such disin- 

 fection is more or less an idea inherited from the earlier days of 

 preventive medicine, and not in conformity with our present knowl- 

 edge. 



