294 



THE TUBERCLE BACILLUS 



(a) 



8th Generation 

 4 months old. 



(W 



5th Generation. 

 28 days old. 



FIG. 187. Tubercle bacilli from cases of 

 Lupus growing on glycerin-potato, (a) The 

 nic or bovine type: (6) the eugonic 



type. (A. S. Griffith.) (See 



material by residence in the tissues of calf and rabbit so as to bring it up to the 

 high virulence of the bovine tubercle bacillus " : and one of the strains of degraded 

 human tubercle bacilli attained the full virulence of the human tubercle bacillus 



after residence in the body of a monkey. 

 No correspondence suggesting any rela- 

 tion between the duration or extent of 

 the disease in the human patient and the 

 degree of attenuation of the bacillus iso- 

 lated was demonstrable in these cases. 



[From thirteen cases of joint and bone 

 tuberculosis the human tubercle bacillus 

 with the full virulence of the type alone 

 was isolated ; in a fourteenth case both 

 human and bovine tubercle bacilli appear 

 to have been present (Cobbett and A. S. 

 Griffith). These investigations therefore 

 afford no confirmation of Arloing's theory 

 so far as it applies to joint or gland 

 tuberculosis. ] 



3. Tuberculosis in the lower 

 animals. 



The majority of the lower animals are 

 susceptible to infection with tuberculosis ; 

 [The infecting agent however is not 

 always of the same type.] 



Bovine animals. Adult animals are 

 frequently tuberculous (3-60 per cent, 

 varying according to the locality), 

 [young] calves very rarely so (1 in 

 10,000 at the most). 



Generally speaking the disease runs a chronic course. Cattle may suffer from the 

 disease for a long time without showing any loss of weight. 



The respiratory organs are most frequently affected : large, occasionally calci- 

 ned, tuberculous masses (Grapes x ) are found in the lungs : the pleurae and especially 

 the bronchial glands are affected at the same time : occasionally the abdomen 

 (mesenteric glands, liver and more rarely the spleen and kidneys) is invaded. Some- 

 times, especially in young cattle, the disease is mainly confined to the alimentary 

 tract : the lymphoid structures of the intestine, the mesenteric glands, peritoneum, 

 liver and spleen being infected. Other local manifestations of the disease are some- 

 times found in cattle ; for instance, mammary tuberculosis (in about 1 per cent, 

 of tuberculous animals), tuberculosis of bone, etc. 



Finally, bovine tuberculosis may occur as a rapidly-spreading generalized infection 

 resembling the miliary tuberculosis of man. 



[The bovine type of tubercle bacillus has been shown to be the sole cause of 

 bovine tuberculosis.] 



Monkeys. In these climates, monkeys frequently develop tuberculosis, 

 and in them the disease runs a course similar to that of human tuberculosis, 

 a characteristic feature being its tendency to become generalized. In these 

 animals the commonest form of the disease is tuberculosis of the lung [and 

 appears to be due mainly to the human type of tubercle bacillus (Rabino- 

 witsch). Thus of twenty-seven cases of tuberculosis in monkeys the human 

 type of bacillus was found in nineteen and the bovine type in three : the 

 avian type, or modified organisms or mixtures of different types were found 

 in the remaining five]. 



Dogs. Tuberculosis is not uncommon among dogs (Cadiot), though the 

 fact has for a long time remained unrecognized. In dogs the lesions often 

 t 1 Fr. Pommeliere ; Ger. Perlsucht.] 



dysgo 



or human 



fig. 186.) 



