Prolonged ether extraction of adult schistosomes removed 25 mg of non-specific ether soluble substances from each 100 mg of worms. The lipids were collected as five fractions, of which two fixed complement with syphilitic sera and two were anticomplementary. None of the lipid fractions fixed complement in the presence of schistosome antibody. A carbohydrate fraction isolated from Schistosoma mansoni worms was non-reactive in the complement fixation test.
Essentially all of the complement fixing activity of the saline extract from ether-treated adult schistosomes is present in the acid insoluble protein fraction. This fraction consists of one demonstrable electrophoretic component, and contains only one-third of the nitrogen and none of the carbohydrate present in the crude extract. The protein precipitates at 30% saturation with ammonium sulfate, but loss of some antigenicity results from this step.
Present address: School of Medicine, University of Southern California, Los Angeles.
Present address: Department of Medical Zoology, Walter Reed Army Institute of Research, Walter Reed Army Medical Center, Washington, D. C.