IMMUNOLOGY 875 



obtaining antigens. Recently Coggeshall and Eaton (1938) have re- 

 ported good results in simian malaria with an aqueous antigen obtained 

 from heavily infected blood or spleen. 



The red-cell adhesion test grew out of Rieckenberg's (1917) blood 

 platelet test. As used by Duke and Wallace (1930), it involves the 

 addition of one drop of a citrated trypanosome suspension to one drop 

 of equal parts of blood from the suspected animal and 2-percent sodium 

 citrate. If the blood comes from an infected animal, red blood cells 

 (occasionally also blood platelets) adhere to the trypanosomes within 

 ten to fifteen minutes. In 1931 Wallace and Wormall concluded that 

 complement is necessary, and H. C. Brown and Broom (1938) found 

 that the concentration of trypanosomes should be between 3,000 and 

 100,000 per cu. mm. and the red cells between 300,000 and 1,250,000. 

 This test compared favorably with specific complement fixation, when 

 untreated horses infected with T. hippicum were tested by W. H. and 

 L. G. Taliaferro (1934d). 



B. Nonspecific Serological Reactions. — Infection often results in defi- 

 nite changes in serum which can be detected by various physical and 

 chemical means and which, although not specific in the immunological 

 sense, are characteristic enough to be useful in diagnosis. Even when 

 the same changes occur in several infections, they may still be used in 

 conjunction with other criteria or if the infections have different geo- 

 graphical distributions. 



Several miscellaneous tests have been devised for kala azar which are 

 associated with an increase in the euglobulins of the serum. They in- 

 clude the serum-globulin test of Brahmachari, the aldehyde test of 

 Napier, and the urea-stibamine test of Chopra, Gupta, and David. These 

 tests have been modified and combined by these same and other work- 

 ers. In general, upon the addition of distilled water, formaldehyde, or 

 urea-stibamine in proper proportions to serum from a person infected 

 with kala azar, the mixture becomes characteristically opaque, owing to 

 the formation of a precipitate within a comparatively short time. These 

 tests appear to be extremely useful and Menon et al. (1936) advocate 

 testing a serum by both the aldehyde and the urea-stibamine test (see 

 Menon et al., 1936, and Chorine, 1937, for the literature on this 

 subject). 



Some of these tests may also be of value in trypanosomiasis (see 



