262 TUBERCULOSIS. 



Not only so, but the ulceration which might be the sequel of 

 the necrosis appeared to open a path for fresh infection. Soon 

 facts were reported which justified these criticisms. Cases 

 where rapid acute tubercular conditions ensued on the use of 

 tuberculin were reported, and in a few months the treatment 

 was practically abandoned. The conditions in guinea-pigs on 

 which the discovery was based have since been found not to 

 be of universal occurrence. 



The Toxins of the Tubercle Bacillus. — The fact that tuber- 

 culin was a powerfully toxic agent stimulated the study of its 

 constituents in the belief that among these the toxins of the 

 tubercle bacillus were present. It was found to contain several 

 albumoses, alkaloids, extractives, and inorganic salts. The 

 albumoses originated a tuberculin reaction in tubercular guinea- 

 pigs, but as has been stated this is also true of ordinary albu- 

 moses. It may be stated that the tuberculin reaction is obtained 

 with the products of the growth of the bacillus in a non-proteid 

 medium. But further, a similar reaction has taken place when 

 tuberculin has been injected into persons suffering from diseases 

 other than tubercle, e.g. cancer, sarcoma, syphilis. Further 

 investigations on this subject are thus required. The toxins of 

 tubercle are thus possibly not of the nature of albumoses. Of 

 their real nature we are still ignorant. From what is known, it 

 is possible that they do not to any great extent diffuse out into 

 the culture media. It has been found that if tubercle cultures 

 are filtered germ-free, the filtrated does not give such a marked 

 tuberculin reaction as the unfiltered fluid. Maragliano has 

 found that such a fluid, however, causes in animals lowering 

 of temperature and sweating, and further that if it is heated at 

 100° C. it now gives a much more marked tuberculin reaction. 

 It is thus possible that more than one toxic body may be formed 

 by the tubercle bacillus, but from what ha;s been said it will be 

 realised that to consider the occurrence of the tuberculin reac- 

 tion as indicating the presence of the products of the tubercle 

 bacillus is not at present justifiable. 



The Use of Tuberculin in the Diagnosis of Tuberculosis in 

 Cattle. — This is now the chief use to which tuberculin is put. 

 In cattle, tuberculosis may be present without giving rise to 

 apparent symptoms. It is thus important from the point of 

 view of human infection that an early diagnosis should be made. 



