236 PATHOGENIC BACTERIA IN MILK 



yet capable of producing in certain animals lesions similar to those 

 of the tubercle bacillus.^ The chief organism coming within such a 

 category is the B. pseudo-tuberculosis of Pfeiffer.- But other workers 

 have described very similar organisms. Klein found this bacillus 

 present in 2 out of 5 samples of London milk,^ and in 8 out of 100 

 samples of country milk delivered in London.* Delepine found 

 that out of 450 samples of milk, lesions produced by pseudo- 

 tubercle bacilli were met with four times. It seems not unlikely 

 that this group of bacilli includes several varieties bearing a close 

 general resemblance to each other, but possessing slightly different 

 properties. They gain access to milk in all probability by some 

 accidental contamination. The milk itself remains unaltered in 

 appearance, though it becomes alkaline. As regards differential 

 diagnosis, it may be said that the pseudo-tubercle bacillus is not 

 acid-fast, nor is it similar to B. tuberculosis in morphological or 

 cultural characters. The pathological changes set up by it, and 

 which form its chief claim to be considered as in any way related 

 to tuberculosis, differ from that disease in showing an absence of 

 giant cells in the nodules, absence of the true tubercle bacilli, 

 copious presence of the pseudo-tubercle bacilli, and a more rapid 

 development of disease. 



Bovine Tuberculosis 



Without entering fully into the conditions and characteristics 

 of bovine tuberculosis (which may be found in any standard work 

 of veterinary pathology), we may say here that the chief anatomical 

 changes are commonly found in the lungs and in the serous mem- 

 branes. In about one half of all cases, the lungs and the serous 

 membranes become simultaneously affected ; in about one third 

 the lungs alone, and in about one fifth the serous membranes alone 

 (Friedberger and Frohner). Tuberculosis of the pleura and peri- 

 toneum produces the well-known " grape disease " (perlsucht). 

 Generally speaking, there is a marked tendency to calcification 



Mt is perhaps unnecessary to add that under this term of pseudo-tubercle 

 we do not inckide the ordinary tuberculosis of animals, protozoal infections, or 

 parasitical disease set up by echinococcus or strongylus in the lungs of cattle. 



^ The pathology and etiology of pseudo-tuberculosis is fully treated of by 

 Klein in the Supplement to the Twenty-Ninth Annual Report of the Local 

 Government Board, 1899-1900, pp. 355-384. See also Atmales de rinstitut 

 Pasteur, 1894, No. 4, and Jour, of Path, and Bad., 1898, pp. 160-181 (Muir). 



•' Report of Local Government Board, 1899- 1900, p. 360, and 1 900-1 901, p. 332. 



* Jour, of Hygiene, 1901, vol. i., p. 83. 



