Blood was taken from canaries with heavy infections of Plasmodium circumflexum and inoculated into seven splenectomized and four normal chicks. Low grade and short-lived infections were obtained in four of the splenectomized and one of the control chicks.
Attempts to transmit the infection from five of the splenectomized chicks to five other splenectomized chicks were unsuccessful.
Attempts to transmit the infection from the splenectomized chicks to canaries were successful in one case from a splenectomized chick which showed parasites, but were unsuccessful from a chick which showed no parasites and from another chick in which parasites were observed.
The results of these attempts to infect splenectomized chicks with P. circumflexum parallel those obtained by Manwell (1933) with normal chicks. In these experiments, the removal of the spleen apparently had no influence on the infection due probably to the fact that the fowl exhibits a great natural resistance to infection with this parasite. Whatever the mechanism of resistance may be, removal of the spleen did not noticeably reduce it.