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further the serum will have to be diluted in order to obtain 

 absolute checking of the same. 



Does the serum of every tuberculosis-sufferer possess this 

 property? I cannot answer to this with absolute certainty, as 

 we have only been able to indicate this peculiarity in the 

 tuberculosis-serum, by comparing sera obtained from tubercu- 

 lous and non-tuberculous individuals. 



Still I already have at my disposal more than loo obser- 

 vations which all gave me a confirmation of this fact. 



Also I have already found that the checking influence of 

 tuberculine is not the same in every tuberculosis-serum, even 

 if the fibrolytic power is the same. With acute, active tubercu- 

 losis the checking action of tuberculine is much weaker than 

 with tuberculosis on the way to recovery. Only a short time 

 ago I was able to indicate with miliair-tuberculosis how the 

 checking action of T in the serum decreased the longer the 

 illness lasted. And on the reverse we find that T in the 

 serum checks more than before, when the illness passes into 

 recovery, or is cured. In a period of 2 months we could often 

 already perceive obvious differences. An increase of the checking 

 action of tuberculine in tuberculosis serum I consider as a 

 prognostic favourable sympton, except however zvith cachectic 

 sufferers. There we often find very low numbers, and this 

 sympton does not hold good. 



In order to increase the practical value of this reaction, I 

 am now engaged in determining the checking-index of each 

 serum. By this term I understand what follows: Determine the 

 decisive dilution of the serum, in which fibrine is no longer 

 transformed, exactly down to i : 50 * parts (consequently i : 700, 

 or 1 : 750 etc.). Also investigate with which dilution of the serum 

 a 2 0/(j tuberculine-solution absolutely checks the fibrine-trans- 

 formation also exactly down to i : 50. The quotient of the first 

 mimber, divided by the second, I propose to call checking-index. 



We need not demonstrate that this index is smaller in 

 tuberculosis-serum than in other sera. Suppose e. g. that the 

 decisive point of the fibrine-transformation of 2 sera A. (tuberculous) 

 and B. (non-tuberculous) is for both in a dilution of i : 500. The 

 decisive point of the absolute checking by tuberculine is of A 1 : 

 300 ; of B. I : 100. Checking-index of A. %%% = if ; of B \%% = 5. 



