INFECTIOUS DISEASES OP CATTLE. 423 



them. All that is necessary is to cultivate in pure culture the tubercle bacilli- 

 found in the tubercular material, and to ascertain whether they belong to bovine 

 tuberculosis by inoculating cattle with them. For this purpose I recommend 

 subcutaneous injection, which yields quite specially characteristic and convincing 

 results. 



These important and comprehensive conclusions followed from a 

 comparatively few experiments upon animals, and apparently no effort 

 had been made to learn to what extent human tubercle bacilli might 

 differ in their virulence for cattle or what grades of virulence there 

 might be among bacilli of bovine origin. Vagedes had already shown 

 that bacilli were sometimes present in human lesions which were as 

 virulent as bovine bacilli, but his work was wholly ignored by Koch. 



A considerable number of investigators, including Chauvean, 

 Vagedes, Ravenel, de Schweinitz, Mohler, De Jong, Delepine, Orth, 

 Stenstrom, Fibiger and Jensen, Max Wclff, Nocard, Arloing, Behring, 

 Dean and Todd, Hamilton and Young, the German Tuberculosis 

 Commission, and Theobald Smith, have found tubercle bacilli in the 

 bodies of human beings that died of tuberculosis, which proved to 

 have about the same virulence for cattle as had the bacilli from 

 bovine animals affected by the disease. 



Kossel, in a preliminary report, stated that the German commission 

 had tested 7 cultures of tuberculosis from cattle and hogs — 4 from 

 cattle and 3 from hogs. Two of these cultures proved acutely fatal 

 in cattle after eight to nine weeks; 4 of the cultures likewise pro- 

 duced a generalized tuberculosis, but which certainly had a more 

 chronic course, while 1 of the cultures caused only an infiltration 

 at the point of inoculation, with some caseous foci in the adjoining 

 prescapular gland and in one of the mediastinal glands, and there 

 was lacking the spreading of the tuberculosis over the entire body, 

 which they were accustomed to see after the injection of cultures of 

 bovine tuberculosis. "Hence," says Kossel, "among bovine tuber- 

 culosis bacilli there can also occur differences with regard to the 

 virulence." 



The German commission also tested 39 different freshly made cul- 

 tures from tuberculous disease in man. Nineteen of these cultures 

 did not produce the slightest symptoms in cattle; with 9 others the 

 cattle exhibited after four months very minute foci in the prescapu- 

 lar glands, which were mostly encapsuled and showed no inclination 

 to progress; with 7 other cases there was somewhat -more marked 

 disease of the prescapular glands, but it did not go so far as a mate- 

 rial spreading of the process to the glands next adjoining. There were 

 4 cultures, however, which were more virulent and caused generalized 

 tuberculosis in the cattle inoculated with them. 



It would appear, therefore, that hereafter everyone must admit that 

 it is impossible always to tell the source of a culture of the tubercle 

 bacillus by its effects when it is inoculated upon cattle. One of the 

 bovine cultures failed to produce generalized tuberculosis in cattle, 



