IOS ANIMAL EXPERIMENTATION 



submitted to the test of experiment. Fever is one of the 

 most marked symptoms of disease. The knowledge \ve 

 have of this, the causes which lead to it, the consequences 

 which follow from it, which knowledge has led to a total 

 change in methods of treatment, has been derived from 

 the study of fever produced experimentally in animals. 

 Our knowledge of the disturbances of the circulation which 

 arise in consequence of disease of the heart and blood 

 vessels, and which again has led to better methods of treat- 

 ment, has been derived from animal experimentation. 



It is interesting to see by what gradual steps knowledge 

 has come. In a disease so common, so well known at 

 present as tuberculosis, the first great step in the chain of 

 investigation which led to our present knowledge was 

 taken in the decade of 1860, when a French investigator 

 showed by inoculating animals with the products of this 

 disease that it could be transferred from one animal to 

 another that it belonged to the infectious diseases. It was 

 further shown by a continuation of animal inoculations 

 that the disease could appear under an infinite variety of 

 forms, that many conditions which were formerly regarded 

 as distinct diseases really were forms of one disease. By 

 a continuation of the study, by applying the methods of 

 bacteriology derived from the experimental study of other 

 diseases, the Bacillus tuberculosis, the actual cause, was 

 discovered by Koch. The practical results in the treat- 

 ment of the disease which have come from the application 

 of this knowledge are enormous. We can guard against 

 infection, we can recognize the disease at so early a period 

 that cure is possible. Statistics show a progressive dimin- 

 ution in the mortality from the disease which has come 

 from the application of what we know. Great as is our 

 knowledge, there arc important gaps which can only be 

 filled by the continuation of the same methods of research. 



The changes in anatomical structure, the lesions of 



