KNOWLEDGE OF ANTITUBERCULOUS SENSITIZERS. 469 



the Bordet-Gengou method to demonstrate the presence of anti- 

 tuberculous sensitizers in tuberculous patients who have received 

 tuberculin. 



I have carried out my experiments on guinea-pigs which have 

 been immunized with the following acid-fast bacilli: the homo- 

 geneous culture of tuberculosis of Arloing*, obtained from Lille, 

 bacillus of fish tuberculosis, the acid-fast butter bacilli of Rabinow- 

 itsch the acid-fast grain bacilli, No. I, and Tobler bacilli, I, II and V, 

 and also the Timothy bacillus and a bacillus from horse dung. Cul- 

 tures of these organisms were grown on glycerin potato without 

 any particular reference as to their age and were dried at 37 degrees 

 for 24 hours in a vacuum. The bacilli were then ground up and 

 used at various periods, subsequently, for injection. Five milli- 

 grams of powder shaken up in salt solution was used for each in- 

 jection in the guinea-pigs. Three such injections were given at 

 intervals of 3 weeks in order to give the animals time for the ab- 

 scesses, which frequently follow, to heal. The guinea-pigs were 

 bled 14 to 21 days after the last injection and the separated sera 

 as well as the normal serum employed for control were heated to 

 56 degrees for half an hour. Sensitizers were then demonstrated 

 by the Bordet-Gengou method, a description of which is given in 

 their first article, f It may be noted here simply that in all these 

 experiments six parts of the serum to be tested were mixed with one 

 part of guinea-pig alexin and two parts of an emulsion of bacilli. 

 This mixture of bacilli is 1 c.c. in volume and contains 80 milligrams 

 of bacilli from a fresh culture. | Three hours later one part of 

 sensitized goat blood was added to each tube.§ In the following 

 table the results of these experiments are given. This table shows 



* These bacteria were kindly given us in part by Dr. Binot of the Pasteur 

 Institute, Paris, and in part by Dr. van Steenberghe of the Pasteur Institute in 

 Lille, to whom I wish to express my indebtedness. 



f I have demonstrated to my own satisfaction that the traces of potato which 

 of necessity must be present in the experimental test tubes with the bacilli, or 

 which are injected into the animal during the immunization have no effect on 

 the result. 



| I have found that it is better to use the fresh cultures instead of the dried 

 bacilli; the dried powder frequently of itself absorbs alexin. 



§ In all my experiments one part of washed goat blood was placed in contact 

 for one quarter of an hour with one part of heated immune serum and subsequently 

 washed, and mixed with two volumes of 0.85 per cent salt solution. 



