When incubating lots of Anopheles quadrimaculatus which have been infected with malaria parasites as the result of a single infecting feed, we are accustomed to dissect and examine at least 10 per cent of the lot while the parasites are still in the cyst stage on the stomachs, in order to get an idea of the qualitative and quantitative incidence of infection. Those examined include nearly all the individuals dying a natural death, supplemented, if the mortality has been negligible, by the examination of a number which have been killed for this purpose. The salivary glands of those mosquitoes used for inoculation are always dissected and examined. The records of gland examination also include a variable number which were not so employed.
A comparison of these results seemed desirable in order to ascertain whether they indicate that the evolution of the sporogonous cycle has been prejudicial to the mosquitoes.