CONTRIBUTION TO THE STUDY OF SENSITIZERS. 



465 



property of sensitizers to fix alexin on the cell for which the sen- 

 sitizer is specific. If a given serum contains an active sensitizer 

 for the tubercle bacillus, the alexin will be fixed by this bacillus, 

 and subsequently introduced sensitized red blood cells will remain 

 intact, owing to the absence of free alexin. 



A resume of our results is given in the following table. Apart 

 from control tubes,* the composition of which is too complicated 

 to write out in detail, each experiment comprises a tube that con- 

 tains 0.1 of a cubic centimeter of guinea-pig alexin, 0.6 of a cubic 

 centimeter of heated serum and 0.2 of a cubic centimeter of an 

 emulsion of fresh human, avian, or bovine bacilli, as the case may 

 be. Three hours later 0.1 of a cubic centimeter of sensitized goat 

 corpuscles is added to each tube.f 



TABLE I. 



+ = Complete fixation; strong sensitizer 

 = Partial fixation; weak sensitizer 

 = No fixation; no sensitizer 



As a result of our researches, we find that human or avian bacilli 

 killed by heating to 65 degrees or 100 degrees stimulate the forma- 

 tion in guinea-pigs of sensitizers active against the various mam- 

 malian tubercle bacilli. This stimulation of sensitizer formation 



* Bordet and Gengou, p. 217. 



t In these experiments washed goat corpuscles are sensitized by an equal 

 volume of rabbit-antigoat serum, and after contact for a quarter of an hour again 

 washed in salt solution; the corpuscles are then suspended in a double quantity 

 of 0.85 per cent salt solution. 



