The susceptibility of anopheline mosquitoes to malaria parasites has both a qualitative aspect (1). Qualitatively, susceptibility is revealed as the proportion of the mosquitoes which become infected after feeding on an infectious patient. Quantitatively it is shown by the numbers of cysts developing on the stomachs of the mosquitoes which become infected.
We have already (2) called attention to the fact that A. crucians is not as effective a host to any of the three commonly recognized species of human malaria parasites as is A. quadrimaculatus. We are at present making a similar comparison of A. quadrimaculatus and A. punctipennis. It is therefore a matter of interest to scan the data available in order to ascertain if possible, whether A. quadrimaculatus itself is equally susceptible to different species of plasmodia.
The observations discussed were made in the course of our routine propagation of parasites for purposes of malaria therapy.