STUDIES WITH ENDAMCEBA HISTOLYTICA 185 



the technique of the tests are described in the paper by Wagener 

 and the reader is referred to this for details. The results of the 

 test as recorded by Wagener were as follows : seven cats were 

 tested which had discharged E. lusfolyfica in the stools for eight 

 days, or longer, and these all gave strongly positive precipitin 

 reactions up to one to four dilutions of the blood serum, while 

 three cats with an infection lasting from six to eight days gave a 

 weak reaction with undiluted blood serum. Six cats dying in less 

 than six days after the development of dysentery gave negative 

 precipitin reactions, as well as five normal cats. The bacterial 

 controls of the antigen always gave negative precipitin reactions. 



PERSOXAL OBSERVATIONS 



For a period of over three years I have been studying com- 

 plement fixation in infections with Endaniceba histolytica and have 

 published preliminary papers upon the subject in 1927 and 1928. 

 Since the publication of these papers additional data have been 

 accumulated regarding the subject which will be noted in this 

 contribution. 



TecJiniqiie. The general technique of the complement fixation 

 test used in this v>^ork has been practically the same as the standard 

 method for performing the complement fixation test for syphilis 

 used in the laboratories of the ^Medical Department of the United 

 States x-\rmy, which is fully described in my book entitled The 

 Wasscrniann Test. The methods of preparing the reagents used, 

 with the exception of the antigenic extracts, and their titration 

 were like those used in the regular complement fixation test for 

 syphilis, as used in the army, except that in titrating the antigenic 

 extracts, owing to their weak antigenic power, it was necessary 

 to use them without dilution. x\ human hemolytic system was used, 

 the blood sera tested inactivated by heating in a water bath at 

 37° C. for one-half hour, and the quantities of blood sera and 

 saline were identical with those used in the standard test for 

 syphilis. The preliminary incubation with antigen and complement 

 was one-half hour in the water bath at 37° C, and the incubation 

 after adding the hemolytic amboceptor and blood suspension was 

 one full hour in the water bath at 37° C. and at least two hours 

 in the ice-box, at the end of which time the results were recorded. 

 The ice-box incubation was very important, for generally hemolysis 

 was far from complete in negative cases at the end of the one hour 



