SEROLOGICAL METHODS IN THE STUDY OF PROTOZOA 431 



ern techniques have ahiiost invariably found negative tests in 

 malaria. 



The chief difficulty in the study of specific complement fixation 

 and precipitation in malaria lies in isolating an intracellular parasite 

 and obtaining a sufficiently high concentration of parasitic ma- 

 terials in the test antigens. Passing over a series of negative or 

 very conflicting results, Gasbarrini (1913 and 1914) reported 

 quite promising results with a test antigen prepared by washing 

 heavily parasitized red cells in 0.9/c saline, laking in distilled 

 water, drying in a desiccator, pulverizing, and for use, diluting 

 I :30 with saline. He obtained positive results only when he 

 absorbed the human serum with sheep cells to remove the natural 

 antisheep antibody. 



Thomson (1918 and 1919) also obtained promising results with 

 an antigen prepared from parasitized cells, first cultivated by a 

 modification of Bass and Johns' (1913) technique; then after 

 hemolysing the red cells, the sedimented parasites and cell debris 

 were dissolved in X/io NaOH, neutralized with normal HCl 

 and just before use diluted with physiological saline until there 

 was no anticomplementary action. Preliminary results with a 

 heavily infected spleen appeared worthy of further investigation. 

 A group reaction occurred among the various malarial parasites 

 and pseudo-positives with syphilitic serums. 



Horowitz-Wlassowa (1924) obtained parasites from localiza- 

 tions in the placenta and brain, extracted them for twenty-four 

 hours in a 0.1% solution of quinine hydrochloride contain- 

 ing a few crystals of thymol and filtered. He concluded that the 

 complement-fixing antibody is formed in malaria but depends 

 upon varying conditions and may be present from two weeks to 

 five years after infection, although during reinfection or relapse, 

 when the parasites, and especially the gametocytes, are increasing 

 in the blood, it is not demonstrable. Savtchenko and Baronoff 



(1926) found infected livers more efficient than spleen and, 

 unlike other workers, obtained definite species specificity. Kings- 

 bury (1927) felt that saline emulsions of washed and hemolysed 

 infected cells were superior to tissue extracts. Manson-Bahr 



(1927) prepared alcoholic extracts of oocysts of plasmodia from 

 the stomachs of mosquitoes, and although he failed to obtain 

 evidence of complement fixation, he believed that if the test 

 antigen could be made stronger it might prove satisfactory. 



