VETERINARY SCIENCE AND PRACTICE. 709 



intertransmissibility of the disease between man and animals and the frequency of 

 such transmission. These questions are discussed in a careful manner with numerous 

 references to the literature of this subject. 



It is concluded that there is "one tubercle bacillus with infinite variations accord- 

 ing to its habitat, whether that habitat is an artificial culture medium or an animal 

 organism, and notwithstanding these variations a bacillus which is always essentially 

 the same, and one which may at any time, if given suitable conditions, retrace its 

 steps and recover the properties which it possessed before the variations occurred." 

 A brief bibliography relating to this subject is appended to the article. 



Spread of tuberculosis among- healthy cattle upon exposure to tubercu- 

 lous cattle, E. C. Schroeder and W. E. Cotton (U. S. Dept. Agr., Bureau of 

 Animal Industry Rpt. 1903, pp. 61-68). — The investigations reported in this paper 

 indicate that all of a herd of cattle may become tuberculous within a year from 

 exposure to one tuberculous animal. The authors describe the arrangement of 

 stalls in a stable in which 7 healthy cattle were kept along with 3 tuberculous cows. 

 Guinea pigs fed milk of a tuberculous cow did not develop the disease. After receiv- 

 ing intraabdominal injections of milk from this cow, however, 2 guinea pigs died of 

 generalized tuberculosis while the third was unaffected. 



Detailed notes are given on the history of each animal belonging to the herd. An 

 examination of the records of this herd shows that all of the 7 healthy animals 

 became affected within a little more than 6 months after exposure, with the possible 

 exception of one animal which had received 5 intravenous injections of human 

 tubercle bacilli. This cow was subsequently killed and numerous minute tubercles 

 all of the same age were found in the lungs. These tubercles were believed to be the 

 result of inoculation with human tubercle bacilli. The animal apparently possessed 

 considerable immunity to further infection. Since, however, the lesions in the lungs 

 still contained living tubercle bacilli 10 months after the last injection was made, 

 this fact is considered as furnishing a serious objection to this method of immuni- 

 zation. 



Among the healthy animals 2 had received injections of dead tubercle bacilli, 

 one of human and the other of bovine origin. These injections had no influence in 

 the production of immunity. Attention is called to the fact that 5 of the 7 origi- 

 nally healthy cattle showed lesions in the mediastinal glands, 3 in the bronchial 

 glands, 4 in the lungs, 2 in the throat glands, 2 in the mesenteric glands, 1 in the 

 liver, and 2 on the pulmonary surfaces. 



It appears, therefore, that stable infection of cattle takes place more commonly 

 through the respired air than through the food. Among 100 guinea pigs which were 

 kept exposed to the tuberculous cattle only one became affected with tuberculosis, 

 and 3 cats which were exposed and received milk from tuberculous cows remained 

 healthy. 



A test of the immunity of treated cattle against a natural exposure to 

 tuberculosis, E. A. de Schweinitz and E. C. Schroeder (Amer. Vet. Rev., 27 

 (1904), No. 10, pp. 961, 962). — In 1902 a cow was given intravenous injections in 

 doses of 10 cc. of a moderately virulent culture of human tubercle bacilli which had 

 been maintained in the laboratory for a large number of generations. The culture 

 was no longer virulent for cattle, but bad still retained its virulence for guinea pigs. 



During the following year the cow was placed in a stall together with tuberculous 

 animals and was repeatedly tested with tuberculin without reaction, after which, in 

 August, 1903, it was killed and examined. The lung was found to be sprinkled with 

 small white nodules, but the other organs and glands showed no tuberculous lesions. 

 The cow treated with human tubercle bacilli appeared to have acquired immunity 

 against the bovine form of the disease. The tubercle bacilli of human origin, how- 

 ever, remained alive for a long period, and the author suggests that "the practicability 



