64 JOURNAI, AND PROCEEDINGS 



factor in the transmission of this widespread and fatal disease 

 was believed to be a specific germ, whose early discovery was 

 confidently predicted by CoJmheim in 1879. 



The announcement of the discovery of the tubercle 

 bacillus was made by Koch in March, 1882, and two years 

 afterv/ards a full report of his researches appeared. His work 

 on this subject stands to-day as probably the master-piece of 

 bacteriological investigation. In the first place, because of 

 the difficulties which had to be overcome in order to make 

 the discovery of the specific germ, and secondly, because of 

 the completeness with which he demonstrated the relation of 

 this organism to the disease. 



The tubercle bacillus cannot be demonstrated in the 

 tissues, as is the case with a variety of other micro organisms, 

 by means of a watery solution of a basic analine dye, and it 

 was only b}^ means of a variation of an ordinary method, 

 worked out by himself and by prolonged staining of 24 hours, 

 that he was able to reveal the germ. 



All attempts to cultivate it on the ordinary media 

 completely failed, but by bringing his able reasoning 

 powers into play, it occurred to him that it might be 

 induced to grow on the solidified serum of an animal's 

 blood, the method- of preparing which he devised 

 himself. Further, no growth was perceptible on the surface 

 of his media till the tenth day at the earliest, a circumstance 

 which might easily have led a less patient and careful 

 observer to the conclusiorj that no growth took place. 



His genius and perseverance overcame successfully in 

 the end every obstacle, and by a long series of inoculation 

 experiments on various animals, he proved that bacilli from 

 tubercular lesions produced like lesions and were the same 

 bacilli. 



His work on this subject Osier considers to be one of the 

 most masterly demonstrations of modern medicine, and its 

 thoroughness appears in the fact that, in the years which 

 have elapsed since its appearance, the innumerable workers 

 on the subject have not, so far as he knows, added a solitary 

 essential fact to those presented by Koch. 



