ANIMALS SUSCEPTIBLE TO TUBERCULOSIS. 285 



As a curative agent for the treatment of tuberculosis, 

 tuberculin has not merited the confidence that was at 

 first accorded to it. Its greatest field of usefulness is 

 now admitted to be as an aid to the diagnosis of obscure 

 cases, and more particularly those occurring in cattle, 

 where it has proven itself to be of inestimable value in 

 this particular application. 



SUSCEPTIBILITY OF ANIMALS TO TUBERCULOSIS. 

 The animals which are known to be susceptible to the 

 tubercular processes are man, apes, cattle, horses, sheep, 

 guinea-pigs, pigeons, rabbits, cats, and field mice. 



White mice, dogs, and rats possess immunity against 

 the disease. 



We have reviewed the three common pathogenic organ- 

 isms with which we may come in contact in the sputum 

 of tuberculous individuals. Occasionally oth er forms 

 may be present. The pyogenic forms are not rarely 

 found, and for some time after diphtheria the bacillus 

 of Lceffler is demonstrable in the pharynx, so that it 

 too may be present under exceptional circumstances. 

 These latter organisms will be described under their 

 proper heads. 



From time to time fowls are known to suffer from a 

 form of tuberculosis that is in many respects similar to 

 human tuberculosis both as regards pathological lesions 

 and etiology. The bacillus causing the disease, while 

 very much like the genuine bacillus tuberculosis mor- 

 phologically, differs from it in cultural peculiarities ; in 

 its inability to produce general tuberculosis in rabbits 

 and guinea-pigs ; in its growth into long branched 

 forms at 45 to 50 C. ; and in its never having been 

 detected in human or mammalian tuberculosis. 



Anatomical lesions very suggestive of those produced 

 13* 



