TUBERCULOSIS. 271 



times causes its death. Opposed to the original opinion of 

 Koch is the fact that the action of tuberculin upon tuber- 

 culous tissues is, however, not specific, and not confined to 

 it alone. As Romer was the first to show, the products 

 derived from other microorganisms by boiling (proteins) 

 induce precisely the same reaction. 



The influence of tuberculin upon healthy and diseased 

 human beings has been tested from both a diagnostic 

 and a therapeutic standpoint in so large a number of cases 

 that a definite opinion can now be expressed. Diagnos- 

 tically, tuberculin has proved an exceedingly delicate 

 reagent for the detection of tuberculous lesions. Subcu- 

 taneous injection of five milligrams is followed by no 

 appreciable effect in healthy persons. In tuberculous in- 

 dividuals, however, this dose gives rise to fever of moderate 

 degree, lasting for several hours, while at the same time a 

 local reaction, manife-sted by redness and swelling, takes 

 place in the tuberculous lesions in so far as these are acces- 

 sible to examination. Initial doses of ten milligrams cause 

 in tuberculous subjects greater and more protracted eleva- 

 tion of temperature, together with headache, nausea, and' 

 vomiting. Similar doses cause also in healthy persons 

 febrile disturbance and general manifestations. 



The undoubted diagnostic utility of minimal doses of 

 tuberculin is rendered practically unavailable from the fact 

 that the injection is followed by febrile movement in all 

 persons who harbor tubercle-bacilli, even when these are 

 latent and encapsulated as, for instance, in lymphatic or 

 bronchial glands. It has been found, in numerous cases, 

 that apparently healthy persons develop fever after injec- 

 tions of tuberculin in the same way as tuberculous patients. 

 From what has been said with regard to the frequent 

 occurrence of tubercle-bacilli in healthy persons, this mani- 

 festation should not occasion surprise ; but a diagnosis of 

 tuberculosis is not, in a clinical sense, justifiable when 

 merely the presence of tubercle-bacilli within the organism 

 has been demonstrated. The conditions are quite different 

 in the diagnosis of tuberculosis than in that of diphtheria 

 or of cholera. It is of the greatest sanitary importance to 

 recognize the existence of diphtheria or of cholera in per- 

 sons in whom, though apparently in perfect health, the 

 exciting agents of those diseases are present in the saliva 

 or in the dejections, because further cases of infection may 



