Toxic Products 381 



resolved into a uniform mass, for when TO was subjected 

 to staining with carbol-fuchsin and methylene-blue it was 

 found to exhibit a blue reaction, while in TR a cloudy violet 

 reaction was obtained. 



The addition of 50 per cent, of glycerin had no effect 

 upon TO, but caused a cloudy white deposit to be thrown 

 down from TR. This last reaction showed that TR con- 

 tained fragments of the bacilli insoluble in glycerin. 



In making the TR preparation Koch advises the use 

 of a fresh, highly virulent culture not too old. It must 

 be perfectly dried in a vacuum exsiccator, and the tritu- 

 ration, in order to be thorough, should not be done upon 

 more than 100 mg. of the bacilli at a time. A satisfactory 

 separation of the TR from TO is said only to occur when 

 the perfectly clear TO takes up at least 50 per cent, of 

 the solid substance, as otherwise the quantity of TO in 

 the final preparation is so great as to produce undesirable 

 reactions. 



The fluid is best preserved by the addition of 20 per cent, 

 of glycerin, which does not injure the TR and prevents 

 its decomposition. 



The finished fluid contains 10 mg. of solid constituents 

 to the cubic centimeter, and before administration should 

 be diluted with physiologic salt solution (not solutions of 

 carbolic acid). When administering the remedy to man, 

 the injections are made with a hypodermic syringe into the 

 tissues of the back. The beginning dose is -g-J-g- mg., rapidly 

 increased to 20 mg., the injections being made daily. 



Experiment showed that TR had decided immunizing 

 powers. Injected into tuberculous animals in too large a dose 

 it produces a reaction, but its immunizing effects were entirely 

 independent of the reaction. Koch's aim in using this 

 preparation in the therapeutic treatment of tuberculosis was 

 to produce immunity against the tubercle bacillus without 

 reactions, by gradual but rapid increase of the dose. In so 

 large a number of cases did Koch produce immunity to 

 tuberculosis by the administration of TR, that he believes 

 it proved beyond a doubt that his observations are correct. 



By proper administration of the TR he was able to render 

 guinea-pigs so completely immune that they were able 

 to withstand inoculation with virulent bacilli. The point 

 of inoculation presents no change when the remedy is ad- 

 ministered ; and the neighboring lymph -glands are generally 

 normal, or when slightly swollen contain no bacilli. 



