XIV INTRODUCTION. 



already found a rod-shaped bacterium in the blood of ani- 

 mals suffering from splenic fever (sang de rate), but they 

 attached no special significance to their discovery until 

 Pasteur made public his grand researches in regard to fer- 

 mentation and the role bacteria played in the economy. 

 Then Davaine resumed his studies, and in 1863 established 

 by experiments the bacterial nature of splenic fever or an- 

 thrax. 



But the first complete study of a contagious affection was 

 made by Pasteur in 1869, in the diseases affecting silk-worms 

 pebrine and flacherie which he showed to be due to micro- 

 organisms. 



Then Koch, in 1875, described more fully the anthrax 

 bacillus, gave a description of its spores and the properties 

 of the same, and was enabled to cultivate the germ on arti- 

 ficial media ; and, to complete the chain of evidence, Pas- 

 teur and his pupils supplied the last link by reproducing the 

 same disease in animals by artificial inoculation from pure 

 cultures. The study of the bacterial nature of anthrax has 

 been the basis of our knowledge of all contagious maladies, 

 and most advances have been made first with the bacterium 

 of that disease. 



Since then bacteriology has grown to huge proportions 

 become a science of itself and thousands of earnest workers 

 are adding yearly solid blocks of fact to the structure, which 

 structure it will be our aim to briefly describe in the pages 

 which are to follow. 



