TUBERCULIN 1 53. 



contains an equivalent of the 0.25 c.c. of the highly concen- 

 trated lymph. This process avoids the necessity of dilutions 

 and, with the addition of a few drops of carbolic acid, the 

 weaker solution keeps perfectly. 



Tuberculin in the dose necessary to bring out its diagnostic 

 effect is absolutelj^ harmless to a healthy animal. Thousands- 

 of observations which have been reported assure us of this fact. 

 Tuberculin is in dail}- use in every state in the Union, in Can- 

 ada and in every country in Europe, yet so far as can be 

 learned not a single case of injury following its use in healths- 

 cattle has been reported. In the tuberculous animal it pro- 

 duces a rise of temperature which, within certain limits, follows 

 a definite course usually terminating in from 18 to 24 hours 

 after the injection. The temperature usually begins to rise in 

 about eight hours giving a stead\- but quite rapid elevation for 

 from I to 3 hours. A continuous high elevation for from 2 to 4 

 hours, possibly longer, and a gradual decline. This is prac- 

 tically constant, be the raise moderate or extreme. In addi- 

 tion to the elevation in temperature there is sometimes a 

 marked nervous chill. Why we get this reaction-'^ is not 

 positively determined. 



*Trudeau (Johns Hopkins Hospital Bulletin, July, 1899) gives the fol- 

 lowing summary of the mechanism of the tuberculin reaction. "The most 

 generally accepted theory at present in regard to it is, briefly, the small 

 dose of tuberculin injected is a partly specific irritant both to tuberculous- 

 foci and to the susceptible organism in general. It produces intense hyper- 

 aemia of all tuberculous tissue in the body (local reaction), and as the re- 

 sult of this hyperaemia nmch toxin stored up in the tubercles themselves 

 is thrown into the general circulation and produces fever and character- 

 istic symptoms which go to make up what is termed 'a general reaction.' 

 That these poisons stirred up in the tubercles are in part at least derived 

 from the dead or weakened bacilli has been shown by the experiments- 

 of Babes and Proca, who found that if two sets of rabbits be injected 

 with equal quantities of living and dead bacilli, the latter react to the 

 tuberculin test at a much earlier period than those inoculated with liv- 

 ing germs. This hypothesis that the general reaction is brought about 

 by toxins already stored up in the tuberculous lesions and exploded as 

 it were by the hyperaemia produced about these lesions as the result of 

 the test injection of tuberculin, is borne out by the fact that a greater 

 amount of albumose can be recovered from the evaporated urine col- 



