BUREAU OF ANIMAL INDUSTRY. 385 



bacillus alone into vigorous, thoroughly healthy guinea pigs and into 

 those that are less vigorous or that have had their vitality reduced 

 through exposure to adverse conditions. For example, pure cultures 

 of the abortion bacillus rarely cause a diseased condition of the joints 

 of the legs Avhen injected into healthy guinea pigs from the station's 

 breeding pens. But when such guinea pigs are injected with cul- 

 tures of the abortion bacillus mixed with cultures of some other germs, 

 which latter are in themselves innocuous, large swellings in the legs 

 in the region of the joints are very common. Likewise when guinea 

 pigs of reduced or low vigor are injected with pure cultures of the 

 abortion bacillus, the joint disease develops in a large proportion. 



From this we may assume that the abortion bacillus, which, if 

 the general literature on the subject can be credited, is capable of 

 causing abortion in widely different species of animals, may be respon- 

 sible, either by acting as an independent factor or in cooperation or 

 symbiosis with some other bacterium or group of bacteria, for various 

 pathological conditions that have been traced to no definite cause, 

 and that the use of heavily infected milk or infected milk for a long 

 period of time in a raw state may hold out an explanation for some 

 of the conditions, the causes of which remain obscure, that affect 

 artificially nourished human infants. 



The subject presented is, to say the least, worthy of careful study, 

 and for the time being we should not fail to recognize that the 

 occurrence of infectious abortion among cattle, and the elimination 

 of the bacillus of infectious abortion with the milk from infected 

 but apparently healthy cows, supplies an argument that can not 

 readily be put aside in favor of the pasteurization, under official 

 supervision, of the entire milk supply. 



TUBERCULOSIS. 



Several series of investigations relative to tuberculosis have been 

 conducted. Fresh evidence has been obtained to prove that bovo- 

 vaccination, or the injection of living tubercle cultures of an insuffi- 

 cient degree of virulence to cause progressive tuberculosis in cattle, 

 is a practice that should be emphatically condemned as unfit for use 

 in the control and eradication of bovine tuberculosis. Among the 

 bovo-vaccinated animals at the station several became affected with 

 meningeal tuberculosis, and two heifers developed tuberculosis in 

 their virgin udders as a result of the vaccination. The development 

 of tuberculosis lesions in the udders of bovo-vaccinated animals has 

 also been observed elsewhere than at the station. How serious this 

 condition is will be more apparent when we bear in mind that the 

 bacilli injected in the practice of bovo-vaccination are of the human 

 type, which cause only a mild, usually retrogressive, disease in cattle, 

 so that an udder affected with such disease may long retain a normal 

 appearance and yet produce milk saturated with tubercle bacilli of a 

 type which, however mild they may be for cattle, we have no reasons 

 to regard as harmless for human health. In one of our earlier inves- 

 tigations on tuberculosis a cow received an injection through her teat 

 into the udder, without trauma, of a very weakly virulent culture of 

 tubercle bacilli of the human type. As a result the milk of the cow 

 contained tubercle bapilli for a period of six years. She never reacted 

 with tuberculin, and she gave birth to and raised two calves that did 



70481°— AGB 1912 25 



