470 Veterinary Medicine. 



have in every case to consider the necessity for receptivity as 

 well as infectivity, and the lack of either is a bar to infection. 

 When, however, we assume that the most diverse tubercle bacilli 

 are descendents of one original stock, that a large herd must fur- 

 nish some animals of more than usual susceptibility, and that 

 such animals are subjected to continuous accessions of both bacilli 

 and toxins, we can easily understand how some of the more 

 adaptable germs will in time accommodate themselves to the new 

 medium. A Pettinkoffer, with an immune constitution or a 

 specially vigorous gastric digestion, may with impunity drink a 

 culture of cholera spirillum, but the sameisnot true of the drunk- 

 ard fresh from a spree and with seriously impaired digestion. 



Bacillus Tuberculosis in Man and Ox. Points of Similarity . 

 The bacillus tuberculosis of cattle is in general shorter and thicker 

 than those of man, but many in both subjects are morphologically 

 indistinguishable. Such differences are often far exceeded by 

 different specimens of one stock of germ seeded on different 

 media. There is no great difference in the thermal death-point, 

 and the viability in light, dryness, cold and putrefaction. The 

 tendency is in all cases to colonize the lymph-plexus or glands 

 and to develop the specific lesions, with slight variation in detail. 

 The slow development of the lesions from both forms of bacilli 

 and their histological similarity is another argument for their 

 essential identity. The slow growth of both on artificial media, 

 the demand of each for a medium having the same approximate 

 composition, and the similar pathogenic and diagnostic characters 

 of the toxic matters elaborated by both germs bespeak a primary 

 identity. The very remarkable staining qualities of tubercle 

 bacillus, from whatever source it may be drawn, are no less 

 remarkable. 



Tuberculosis of Man and Ox Coextensive. The prevalence of 

 tuberculosis in man and ox in the same country and district is so 

 frequent that it may be safely set down as the rule. Among 

 ichthyophagists and great fishing communities, like the people of 

 the Hebrides, Iceland, Newfoundland, Greenland, and the coasts 

 of Hudson Bay, tuberculosis is rare. In these countries cattle 

 are few or absent, or, like the hardy highland kyloes of the 

 Hebrides, they are kept in the open air. The immunity of the 

 people is not due to insusceptibility, since they fall ready victims 

 to tuberculosis when removed to infected countries and cities. 



