Since distinct differences in the susceptibility of several species of anopheline mosquitoes to co-indigenous or exotic strains of malaria parasites have been observed, it appeared desirable to extend these observations to separate strains of the same anopheline species. Opportunity for such a study was afforded through the courtesy of Dr. Herbert S. Hurlbut of the Health and Safety Division of the Tennessee Valley Authority, who supplied a local strain of Anopheles quadrimaculatus colonized in an insectary at Wilson Dam, Alabama, by Mr. R. L. Crowell in 1939. This strain (T.V.A.) has been readily maintained in our own insectaries for several months, successive generations being reared according to the same technique utilized in the propagation of our own strain.
Lots of each strain were applied simultaneously to infectious patients. After the separation of the engorged from the unengorged specimens, the former were incubated at a temperature of approximately 20°C.