STUDIES ON MALARIAL PARASITES : VII. METHODS AND TECHNIQUES FOR CULTIVATION.

1. Methods of recovering adequate amounts of Plasmodium knowlesi from the monkey (Macaca, mulatta) for biochemical studies and in vitro cultivation are described. Concentrates of red blood cells parasitized with P. knowlesi can be obtained by differential sedimentation of parasitized blood because of physical and chemical changes produced by the parasites in the host cell and the plasma of the blood. 2. Two different techniques, the rocker-dilution and the rocker-perfusion methods, are described for the cultivation of malarial parasites. Details of the apparatus, assembly, and sterilization are given, as well as methods of counting and evaluating parasites. 3. In a series of 235 control experiments for 20 to 24 hours using three types of apparatus, the average rate of multiplication was 3.9. Each technique has specific value for studying the various aspects of metabolism, nutrition, and the action of antimalarial drugs.