4C8 ANNUAL REPORT OF THE Oft. Doo. 



expei'imentecl on small aniuials, such as rabbits and guinea-pigs, I 

 failed to arrive at any satisfactory results, though indications which 

 rendered the difference of the two forms of tuberculosis probable 

 were not wanliiig. Not till the complaisance of the Minister of Agi- 

 culture enabled me to experiment on cattle, the only animals really 

 suitable for these investigations, did I arrive at absolutely conclusive 

 results. Of the experiments which I have carried out during the last 

 two years along with Trofessor Shiietz, of the Veterinary College i« 

 Berlin, I will tell you briefly some of the most important. 



A number of young cattle which had stood the tubcLculin test, 

 and might therefore be regarded as free from tuberculosis, were 

 infected in various ways with pure cultures of tubercle-bacilli taken 

 from cases of human tuberculosis; some of them got the tubercular 

 sputum of consumjitive patients direct. In some cases the tuber- 

 cle-bacilli or the sputum were injected under the skio, in others into 

 the peritoneal cavity, in others into the jugular vein. Six animals 

 were fed with tubercular sputum almost dail}- for seven or eight 

 months; four repeatedly inhaled great quantities of bacilli, which 

 were distributed in water, and scattered with it in the form of spray. 

 None of these cattle (there were nineteen of them) showed any 

 symptoms of disease, and they gaitied considerably in weight. From 

 six to eight months after the beginning of the experiments they 

 were killed. In their internal organs not a trace of tuberculosis was 

 found. Onl}' at the places where the injections had been made small 

 sui)purative foci had foiTued, in which few tubercle-bacilli could be 

 found. This is exactly what one finds when one injects dead tuber- 

 cle-bacilli under the skin of animals liable to contagion. So the 

 animals we experimented on were affected b}' the living bacilli of 

 human tuberculosis exactly as they would have been by dead ones; 

 they were absolutely insusceptible to them. 



The result was utterly difterent, however, when the same experi- 

 ment was made on cattle free from tuberculosis with tubercle-bacilli 

 that came from the lungs of an animal suffering from bovine tuber- 

 culosis. After an incubation-period of about a week the severest 

 tubercular disorders of the internal organs broke out in all the in- 

 fected animals. It was all one whether the infecting matter had been 

 injected only under the skin or into the peritoneal cavity or the vas- 

 ciilar system. High fever set in, and the animals became weak and 

 lean; some of them died after a month and a half to two months, 

 others were killed in a miserably sick condition after three months. 

 After death, extensive tubercular infiltrations were found at the 

 place where the injections had been made, and in the neighboring 

 lymphatic gla«ds, and also far advanced alterations of the internal 

 organs, especially the lungs and the spleen. In the cases in which 

 the injcf lion h:id l>ecn nuule into the peritoneal cavity the tubercular 



