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Bacteriology assists materially in tlie prompt diagnosis of many 

 of the contagious diseases, such as diphtheria and tuberculosis, making 

 early isolation and quarantine possible. 



The old idea that consumption was a constitutional disease has been 

 exploded. Dr. Koch, in 1882, declared this to be a germ disease. Expe- 

 rience has shown that there are as many as two million bacteria in 

 a single expectoration. It is undoubtedly through the medium of the 

 sputum that most of the consumption is spread, and these facts point 

 out the necessity and importance of precautionary measures. 



There have been many recent discoveries made by bacteriologists 

 showing that certain diseases are due, not to bacteria, but to animal 

 parasites, protozoa. There are many cases in which these animal par- 

 asites appear to be carried through the agencj' of insects. An example 

 of this is the carrying of malaria germs by the mosquito. This has led 

 the sanitarian to make important crusades against the mosquito, de- 

 stroying their breeding places, and in this way checking a spread of 

 the disease. 



Experiments with the common house fly have shown that these in- 

 sects carry infected material on their legs and probosces. Hence the 

 need of disinfecting all germ-bearing material which may come within 

 the reach of the fly. Also the destruction of their breeding places so 

 as to reduce as far as possible the numbers of these insects. 



The discovery of antitoxic serums, the direct or indirect products of 

 bacterial action and growth, have been a great advance in bacteriology 

 and medicine, not only for the curing of disease, but, more important, 

 for protection against disease as well. The use of protective serums 

 is now in its infancy, and I look forward to the time when the bac- 

 teriologist shall have discovered or manufactured, with the assistance 

 of the bacteria, a serum or mixture of serums with which we may 

 be inoculated, and thereby protected against all diseases, perhaps through- 

 out life. That would indeed be a great factor in preventive medicine. 



These facts show briefly the great and incalculable assistanc;e given 

 to sanitary science by one of the youngest of the many "ologies." That 

 the sanitary scientists have taken advantage of this aid is evidenced by 

 the attention which they everywhere receive, and the importance which 

 is now attached to their dictum and doings. They can now compel 

 legislation to enforce safeguards against disease, and it is a benighted 



