VETERINARY SCIENCE AND PRACTICE. 691 



led to au extended investigation of the subject. Some of the earlier 

 experiments have been previously reported. 1 



In the present publication 12 experiments with cattle are described 

 in considerable detail. Six animals were inoculated with human bacilli, 

 5 with bovine bacilli, and 1 with swine bacilli. In all cases cultures 

 isolated by the author were used. Inoculations were first made on 

 guinea pigs, and from them after 3 to weeks cultures on dog serum 

 were made. These were tested upon rabbits and guinea pigs and lastly 

 on the cattle. In all the tests the experimental conditions were kept 

 as nearly uniform as possible. Of the G cases inoculated with bacilli 

 from sputum 1 showed no disease, 2 very slight lesions, and 3 only local 

 lesions without dissemination. Of the 5 cases inoculated with bovine 

 bacilli, 2 died of generalized disease, 2 showed extensive lesions, and 1 

 less extensive lesions. The animal inoculated with swine bacilli, which 

 the author remarks were probably originally bovine, showed less exten- 

 sive lesions than the animals inoculated with bovine bacilli. 



"We may now maintain that bovine tubercle bacilli and human bacilli as found 

 in sputum are not identical. The difference in their action upon cattle is reinforced 

 by certain differences in the bacilli themselves and their effect upon rabbits. . . . 



" What the significance of these divergencies is, what influence they have upon 

 the transmissibility of the disease from cattle to man, we are unable at present to 

 state with any degree of certainty. That they do have some effect must be admitted 

 in view of results of studies upon other species of pathogenic bacteria. Their pre- 

 cise bearing needs careful investigation. 



"These studies will, I think, warrant one inference, however; that is, that human 

 sputum can not be regarded as specially dangerous to cattle, nor can it be looked 

 upon as a factor in the introduction of tuberculosis into a healthy herd of cattle. 

 Even if the tubercle bacilli of cattle and of man are very closely related and have 

 the same ancestry, as we all must admit, if we regard the two as mere varieties, 

 which may eventually, under very favorable conditions, pass one into the other, the 

 condition in which the bacillus leaves the lungs in sputum is evidently such as to 

 interfere, under ordinary circumstances, with any development in the bovine body. 

 It would fall a speedy prey to destruction. 



"I refrain, for obvious reasons, from drawing the conclusions that all human 

 tubercle bacilli are like those existing in the sputum of phthisis." 



A comparative study of bovine tubercle bacilli and of human 

 bacilli from sputum, T. Smith (Jour. Exptl. Med., 3 (1898), X<>. 

 4-5, pp. 451-511). — In this publication the author describes the experi- 

 ments noted above, and in addition reports comparative tests of bovine 

 tubercle bacilli and bacilli from human sputum upon rabbits, gray mice, 

 and pigeons. 



"The foregoing experiments, while they show unmistakably theclose relationship 

 existing aiming the various cultures studied, nevertheless justify us, if only to guide 

 and stimulate fmther study, in establishing a distinctively human or sputum and 

 a bovine variety of the tubercle bacillus. . . . The characters upon which the 

 bovine variety may be based reside, morphologically, in the invariably short, straight 



'Trans. Assoc. Anier. Physicians, 1896, pp. 75-93. U. S. Dept. Agr., Bureau of 

 Animal Industry Rpt, 1895-96, pp. U9-161 (E. S. R., 9, p. 889). 



