In a previous paper (1) we expressed our opinion as to the minimal leucocyte-gametocyte ratios requisite for the certain propagative recovery of malaria parasites, in order to secure the maximum degree of qualitative and quantitative infection of the anophelines employed. For the intensive infection of A. quadrimaculatus we consider that, with an equal distribution of the sexes, the desirable ratios are approximately 2 gametocytes to 100 leucocytes in the case of P. vivax and 22 gametocytes to 100 leucocytes in the case of P. falciparum. These roughly may be considered the equivalent of 100 and 1100 gametocytes per cubic millimeter. While these data are technically important to a naturally induced malaria therapy service, they have little epidemiological significance. The latter viewpoint requires data illustrating the minimal gametocyte density capable of producing the least possible infection of anophelines.