TUBERCULOSIS. 235 



" These facts formed the basis of a therapeutic method 

 against tuberculosis. But an obstacle to the practical em- 

 ployment of fluids containing in suspension the dead 

 tubercle bacilli was found in the fact that the tubercle 

 bacilli are not (readily) absorbed ; they disappear, and 

 remain for a long time unchanged in situ, producing 

 larger or smaller suppurating centres. It was clear, there- 

 fore, that in this method the curative effect on the tuber- 

 culous process was obtained by a soluble substance, diffused 

 so to speak, into the fluids that surround the tubercle bacilli, 

 and transferred without delay to the circulating fluids of the 

 body ; whereas that which has the pus-forming quality 

 seems to remain bound up in the tubercle bacilli, or at any 

 rate to be only very slowly dissolved or washed out. Thus 

 the only important thing that remained to be done was to 

 carry out the process that takes place within the body 

 outside of it also and if possible to extract and isolate the 

 curative substance from the tubercle bacilli. This problem 

 required long and continued experimentation, but at last I 

 succeeded, by the help of a 40 to 50 per cent, solution of 

 glycerine, in extracting the active principle from the tubercle 

 bacilli. My further experiments on animals, and finally on 

 human beings, were made with liquid thus obtained ; and 

 in this way, also, the liquid which I supplied to phy- 

 sicians and surgeons in order that they might repeat the 

 experiments, was obtained. The remedy with which the new 

 therapeutic treatment of tuberculosis is carried out, is, there- 

 fore, a glycerine extract of pure cultivations of tubercle 

 bacilli. 



" In addition to the active principle there pass from the 

 tubercle bacilli into the simple extract all other substances 

 soluble in 50 per cent, glycerine, and therefore it is found to 

 contain a certain quantity of mineral salts, pigment, and 

 other unknown substances extractives, &c. Some of these 

 substances can be readily separated, as the active principle 

 is insoluble in absolute alcohol, by which it can be preci- 

 pitated, not pure certainly, but in combination with such 

 other extractive matters as are also insoluble in alcohol. 

 The colouring matter, too, can be separated out so that it is 

 possible to obtain from the extract a colourless dry substance, 

 which contains the active principle in a much more concen- 

 trated form than does the original glycerine solution. 



