TUBERCULAR DISEASE. 195 



and described by Gordonius. From that time our 

 knowledge of tubercular disease has been slowly grow- 

 ing; for centuries, progress, if there were any, was 

 very small, but within the past hundred years our 

 knowledge has grown apace, investigation having been 

 rewarded time after time by discovery. It had long 

 been known that tubercular disease could be com- 

 municated by inoculation of tubercular matter (as the 

 sputum of a phthisical person), or by feeding an 

 animal upon the flesh of animals which were tuber- 

 cular; but it was not until 1882 that the disease 

 was robbed of its last secret by the discovery, by 

 Professor Koch of Berlin, of the micro-organism upon 

 which all tubercular disease depends. This eminent 

 scientist discovered that in all tubercular growths 

 there are to be found myriads of micro-organisms 

 having characters peculiar to themselves. This disease 

 germ, which Koch named the "tubercle bacillus," is 

 to be found in every case of tubercular disease, and 

 will, if introduced into the system of an apparently 

 healthy animal, light up tubercular disease. It can, 

 moreover, with proper attention to temperature, and 

 in a proper medium, be multiplied indefinitely outside 

 the living body altogether, and such artificially culti- 

 vated germs, when inoculated upon the living animal, 

 produce tubercular disease, just as would matter taken 

 from a diseased person or animal. 



Professor Koch's discovery of the tubercle bacillus, 

 although the existence of the germ had for some 

 time been suspected, caused great stir in the medical 



