io8 Bulletin 65. 



Tuberculosis Contagious. 



In the middle ages tuberculosis in animals was recognized as 

 contagious and laws were made against the use of the aflfected 

 carcasses as human food, which remain in force in Italy and 

 Spain to the present day. In the i6th century the disease was 

 confounded with syphilis and at the end of the 1 8th century with 

 glanders, blunders which, however untenable, show the strong 

 conviction that the malady was contagious. The propagation by 

 contagion in herd was recorded in Germany by Ruhling (1774), 

 and Krunitz (1787), and more recently by Spinola, Zannger and 

 others. In France the same is claimed by Fromage, Huzard, 

 Lafosse, Dupont, and Cruzel. 



It must be allowed, however, that in the first half of the pres- 

 ent century, the manifest tendency of the disease to run in fam- 

 ilies, and to develop under special unwholesome conditions of 

 life, served to weaken the belief in contagion, and in Central and 

 Western Europe such belief had become practically extinct among 

 medical men, when their attention was recalled to the subject by 

 the successful inoculations of tuberculosis on rabbits and guinea- 

 pigs, b}^ Villemin,in 1865. The subject was taken upon all sides 

 by incredulous experimenters and for a time a keen polemic war- 

 fare raged, but slowly the stern logic of constantly accumulating 

 and unanswerable facts compelled all candid observers to accept 

 the doctrine of contagion. 



The Germ. Bacillus Tuberculosis. 



An even fuller demonstration came in 1882, when Robert Koch, 

 of Berlin, demonstrated the existence of the tubercle bacillus, 

 and showed that the disease could be produced with equal cer- 

 tainty by inoculating with the substance of a tubercle from the 

 ox's lung, or with a pure culture of the germ grown on pepton- 

 ized gelatine, apart from the living body. Before publishing his 

 discovery Koch demonstrated the presence of the bacillus in the 

 expectoration or tubercle of over 100 cases of consumption, and 

 had successfully inoculated 472 subjects — guineapigs, rabbits, 

 mice, rats, and cats, besides dogs, pigeons and chickens. The 

 following are some of the characteristics of this germ : 



Form. — A delicate rod with rounded ends, 1.5 to 3.5 micromillimeter in 

 length (about i-2500th of an inch). They occur singly, or in pairs or chains 



