VARIATIONS IN TYPHOID BACILLI 309 



AGGLUTININ ABSORPTION TESTS OF XYLOSE QUICK FERMENTER 

 AND XYLOSE SLOW FERMENTER 



The next experiments were undertaken to determine whether 

 xylose quick fermenters and xylose slow fermenters differed in 

 regard to serum reactions. 



We immunized rabbits against the xylose fermenting strains 

 "Cohen" and "no. 3," and against the xylose slow fermenters, 

 C-51, Rawling, and C-188. The serum titre of each strain was 

 between 1:10,000 and 1:15,000 for each strain. Three agar 

 slants of xylose quick fermenter twenty-four hours old were 

 prepared and a suspension in 5 cc. of 0.85 per cent salt solution 

 made. To each suspension was added 5 cc. of each correspond- 

 ing serum in dilution of 1:50. The tubes were then incubated 

 for three hours at 37°C. After that, we centrifuged them for 

 half an hour at high speed, and pipetted off the supernatant 

 fluid. This was then made up with 0.85 per cent salt solution 

 into a series of dilutions ranging from 1:100 to 1:16,200. To 

 0.5 cc. of each dilution was added 0.5 cc. of the suspension of a 

 xylose quick fermenter, and similarly to another series of dilution^ 

 0.5 cc. of a suspension of a xylose slow fermenter was added. 

 The two series were incubated for two hours at 37°C., and allowed 

 to stand overnight in the ice-chest. The results were read 

 before placing in the ice-chest and again the next morning. 

 As controls, agglutination tests were carried out using the original 

 strains and fresh unabsorbed serums. 



After absorption of both sera by slow xylose fermenters we 

 found that practically all agglutinin had been removed. The 

 only exception to this was a slight persistence of agglutinin in 

 the tube containing the 1 : 200 dilution. Vice versa we absorbed 

 the serum produced with xylose quick fermenters by means of 

 a xylose slow fermenting organism and then looked for traces 

 of agglutinin by adding suspensions of both xylose rapid fer- 

 menting and xylose slow fermenting strains. The results were 

 the same as those obtained above. 



Control tests gave negative results. 



Xylose slow fermenters and xylose quick fermenters are there- 

 fore not serologically different! 



