We have already (1, 2, 3) submitted some observations indicating the influence of the sporozoite dosage on the duration of the incubation period and clinical attack in vivax malaria. The pertinent relation of the present data to this subject justifies its submission.
The anopheline mosquitoes we employ in inoculation are always dissected subsequent to their application, and their salivary glands are examined for the presence of sporozoites. Regardless of the number of living mosquitoes from a lot which may have been applied for the inoculation, the inoculation is recorded as having been effected only with the number of those applied in which salivary infection was subsequently detected. A rough guide to the quantitative infection of the various lots of these mosquitoes is afforded by the number of cysts observed in the stomachs of those dissected from a lot before infection was matured. On the basis of these observations, anopheline lots are given the following ratings: