620 Tuberculosis. 



that human beings were only slightly susceptible to the contagion 

 of pearl disease ; in view of all this, however, he did not regard the 

 possibility of human infection with bovine bacilli (especially in children 

 ingesting large quantities of bacilli with milk from cows with tuber- 

 culosis of the udder) as out of the question. Even before Theobald 

 Smith, Sidney Martin, Frothingham and Dinwiddle had made similar 

 observations in regard to the variability in the pathogenic action of 

 these two types of bacilli, although Frothingham oliserved rather ex- 

 tensive morbid changes in the peritoneum and in the mesenteric lymph 

 glands of calves that were infected with bacilli from a tuberculous 

 child while Dinwiddle, on the other hand, found that in one case material 

 obtained from a tuberculous cow proved avirulent for a calf. Accord- 

 ing to Dinwiddle the differences exhibited by the two forms of bacilli 

 manifest themselves only in horses, cattle, dogs and eats, while the 

 human as well as the bovine types of bacillus produce generalized 

 tuberculosis in swine. Finally Vagedes succeeded in procuring human 

 cultures that had pathogenic properties very similar to those obtained 

 from cattle. 



The question of identify or non-identity attracted renewed 

 attention ^vhen Robert Koch announced it at the London 

 Tuberculosis Congress in 1901 as his emphatic vie^v "that 

 human tuberculosis differed from bovine tuberculosis;" that 

 the former ^vas not transmissible to cattle and ''that accord- 

 ingly it did not seem necessary to take any measures whatever 

 for the protection of milk, butter and cheese from tuberculous 

 cattle against infection with the germs of this disease." 



Koch based this view on the results of infection experiments that he had con- 

 ducted with the co-operation of Schuetz. 19 calves were treated with the pulmonary 

 discharges of tuberculous persons and with cultures of human tuliercle bacilli which 

 material was administered with the food, with the inhaled air, or the cultures were 

 injected intravenously, subcutaneously or intraperitoneally; all of the calves 

 remained perfectly healthy, increased steadily in weight and, at post mortem 

 examination several months later only caseous abscesses could be detected at the 

 point of inoculation. On the other hand, six calves given subcutaneous, intra- 

 peritoneal or intravenous injections of bovine cultures of bacilli developed fever 

 and became very sick. At post-morten examination tuberculous changes were 

 found not only at the point of inoculation and in the regional lymph glands Imt 

 there was extensive tuberculosis of the internal organs, especially in the lungs and 

 spleen. Of six pigs that had been fed for 104 days with tuberculous sputum 

 mixed with the food, small scattered tuberculous nodules developed in the cervical 

 glands and in the lungs and mesenteric glands of two of the animals while the 

 remaining pigs remained unaffected. On the other hand, of six pigs that had 

 been fed for 70 days with cultures of bovine bacilli, all contracted extensive 

 lesions of tuberculosis. Subcutaneous, intraperitoneal and intravenous injections of 

 human tubercle bacilli proved harmless in 5 pigs while the 6th animal, whiidi 

 received an intravenous injection, developed miliary tuberculosis of the lungs and 

 mediastinal glands. Two sheep were unaffected by subcutaneous injections of 

 cultures of human bacilli while one, receiving an intravenous injection, developed 

 slight tuberculous changes in the lymph glands of the lungs. On the other hand, 

 sheep treated in a similar manner Avith cultures of bovine bacilli became very 

 sick. 



The large number of experimental animal inoculations that 

 have been made since Koch's epoch making address, according 

 to which the bacillus of human tuberculosis as compared ^vitli 

 that of bovine tuberculosis is only slightly or not at all patho- 

 genic for cattle, as sliow^n by the investigations of Koch tS: 



