Sept. 23,1918 Improved Method for Recovering Trypanosomes 
575 
The trypanosomes in flask 1 were recovered by repeated centrifugali- 
zation, the machine being run a sufficient length of time to drive all the 
corpuscles to the bottom of the tube, but leaving a large number of try¬ 
panosomes in the supernatant fluid. This was pipetted off and the blood 
mixed with salt solution and again centrifugalized. By repeating this 
operation a number of times, as many trypanosomes as possible were 
obtained in suspension. This fluid was then centrifugalized, driving all 
the trypanosomes to the bottom of the tube. The supernatant fluid was 
discarded and the trypanosomes were suspended in the following solu¬ 
tion: Glycerin 5 cc., physiological salt solution 5 cc., and labeled “ Anti¬ 
gen I ” 
The trypanosomes in the second flask were recovered by breaking up 
the red blood cells with distilled water in the manner hereinbefore 
described. These trypanosomes were also suspended in 5 cc. of glycerin 
and 5 cc. of physiological salt solution and labeled “Antigen II.” 
On inspection of the two antigens it was readily seen that Antigen II 
contained many more trypanosomes than Antigen I and apparently no 
blood corpuscles, while Antigen I showed the presence of considerable 
blood which it had been impossible to get rid of without sacrificing many 
of the trypanosomes. 
Both antigens were titrated for antigenic strength and anticomple¬ 
mentary action immediately after preparation and after being stored in 
the ice box for two weeks. Tests for hemolytic action were also made. 
The hemolytic system employed consisted of a 3 per cent suspension 
of sheep red cells, units of hemolytic amboceptor, and 1% units of 
complement, the latter being titrated against the amboceptor and sheep 
cells. 
Both antigens were diluted 1 to 10 with physiological salt solution. 
The test for antigenic power was made against 0.15 cc. of known posi¬ 
tive dourine serum, which was the pooled serum from 20 horses affected 
with dourine. 
In the test immediately after preparation the antigenic unit of Antigen 
I was 0.25 cc. and the anticomplementary unit was 2 cc., and was not 
hemolytic in five times this amount. The antigenic unit of Antigen II 
was 0.05 cc., the anticomplementary unit 3 cc., and was not hemolytic 
in five times this amount. 
Two weeks after preparation the antigenic unit of Antigen I was 0.35 
cc., the anticomplementary unit 1.5 cc., and the antigen showed no 
hemolytic action. The antigenic unit of Antigen II was o. 1 cc., the anti¬ 
complementary unit 3 cc., and it showed no hemolytic action. 
