The problem of sporozoite dosage as a factor in determining the duration of the incubation period and clinical attack with vivax malaria is of considerable interest. Its exact solution awaits the discovery of a satisfactory menstruum for the suspension and dilution of sporozoites mechanically removed from the salivary glands. We have already presented some data bearing on this subject (1, 2), and consider that the highly confirmatory character of the present supplemental material justifies its submission.
It may reasonably be inferred that, if mosquitoes are consecutively applied to several subjects, without a replenishment of their supply of sporozoites, the numbers in their glands will gradually be depleted, and the last patient to whom they are applied will be inoculated with a much smaller number of sporozoites than was received by the first patient.
On different occasions, in connection with the performance of immunity observations (usually heterologous), we have applied various lots of mosquitoes in a consecutive manner, in order to demonstrate that the patient whose immunity was being tested actually received an infectious dose of sporozoites.