Serum Anaphylaxis in Guinea Pigs. 105 



several months ago which led us to believe that dogs sensitized 

 with tuberculin would show an arterial depression if injected upon 

 the following day with tuberculin. 



We have tested several "crude" tuberculins which have been 

 heated in the autoclave at from 7 to 10 lbs. pressure for 30 

 minutes. The temperatures at these pressures varied approxi- 

 mately from 1 io° C. to 1 1 5 0 C. We have also tested the uncon- 

 centrated filtrate from he tubercular culture when it has reached 

 a condition ready for concentration into "crude" tuberculin. 

 Dogs sensitized with some of the samples of tuberculin which 

 have been heated in the autoclave do not produce the reaction 

 if injected upon the following day with the same tuberculin. Serum 

 of dogs sensitized with the unconcentrated filtrate from the cul- 

 ture of B. tuberculosis of six weeks growth did produce a well 

 marked reaction when injected into the dog on the following day. 



A temperature of 105 0 C. was found to practically destroy the 

 depressor substance in the unconcentrated filtrate. 



The following are the experiments in detail as they were 

 conducted : 



Protocol of March g. — Bull dog, 35 lbs., sensitized March 8, with 5 c.c. of a fresh 

 preparation of crude tuberculin which had been heated in the autoclave for 30 minutes 

 from no° C. to 115 0 C. 



1. 1 and 2 drops injected as usual, gave no results. 



2. 2 drops of an older preparation of crude tuberculin used in January for sensitiz- 

 ing in experiments with tubercular serum gave a well marked depressor reaction. 



3. 3 and 5 drops of the fresh tuberculin gave no reaction. 



4. 6 drops of the January tuberculin gave a sharp reaction. 



Protocol of March it, — Dog, mongrel collie, 50 lbs., sensitized March 10, 1910, 

 with 5 c.c. crude tuberculin which was heated in the autoclave for 30 minutes from 

 no 0 to 115° C. 



1. 1, 3 and 10 drops of the tuberculin with which the dog was sensitized produced 

 no reaction. 



2. 10 drops of the same tuberculin after further concentration on the water bath 

 produced a marked reaction. 



3. 3 drops of the January tuberculin gave a slight reaction and 10 drops gave 

 a sharp reaction. 



4. 10 drops of the tuberculin used in the experiment of March 9 did not give a 

 reaction. 



Protocol of March 16. — Dog, 20 lbs., sensitized March 15, 1910, with 5 c.c. of 

 an unconcentrated, unheated filtrate from the culture of B. tuberculosis ready for 

 concentration. 



1. 2 drops and 0.5 c.c. (10 drops) of this unconcentrated filtrate failed to give a 

 reaction. 



