466 STUDIES IN IMMUNITY. 



is also possible in a rabbit, particularly with human bacilli that have 

 been heated to 100 degrees, but, as is evident from the table, it is 

 more difficult to produce.* The facts that we have observed, 

 however, as regards the rabbit, and particularly in the guinea- 

 pig, prevent our adherence to Dembinski's opinion, who thinks 

 in regard to the rabbit and the pigeon that "the injection of 

 killed bacilli, whether human or avian, produces no sensitizer in 

 their blood." 



We feel justified in concluding from our results that, contrary 

 to Dembinski's opinion, tlie production of antituberculous sensiti- 

 zers does not depend on the type of bacilli injected. The human 

 bacillus as well as the avian bacillus, and acid-resisting bacilli 

 in general, may give rise on injection in the rabbit, and par- 

 ticularly in the guinea-pig, to sensitizers that are active for the 

 various types of mammalian tubercle bacilli, as we shall later show. 

 It may be, however, on the other hand, that the facility with which 

 these antibodies are formed depends on the animal species em- 

 ployed ; and the guinea-pig would seem to yield them more readily 

 than does the rabbit, or, according to Dembinski, the pigeon. 



We have been able to confirm the other results of this writer, 

 who found that antituberculous sensitizers are just as active when 

 heated human or avian bacilli (one-half hour to 65 degrees) are 

 employed. 



* The slight activity of the serum from the majority of our vaccinated rabbits 

 may be due simply to insufficient immunization; we are, for the moment, 

 engaged in a study along this line. 



