In a previous paper (1) we have shown that various North American strains of Plasmodium vivax in our hands have displayed remarkably constant incubation periods during several years of observation. The range of duration was found to lie within a period of from 8 to 23 days. Up to the experience of the case herein discussed, no indubitable examples have occurred in our service that duplicate the instances of protracted latency described by various European observers.
The patient whose case is presented, no. 285, is a white male, aged 15 years, to whom Anopheles quadrimaculatus of Lot 570, infected with the McCoy strain, were applied on June 21, 1937, and reapplied on the 25th. Five other patients were inoculated with mosquitoes from the same lot on the same dates. On the 21st, 12 mosquitoes fed and on the 25th, 10 of the survivors were reapplied. Upon dissection four were found to be infected.