Quarterly Journal of Microscopical Science, Vol s3-100, 241-255, Copyright © 1959 by Company of Biologists

The Feulgen Reaction in the Different Stages of the Life-cycles of Certain Sporozoa

¹ Department of Parasitology, London School of Hygiene and Tropical Medicine, London; Biological Laboratory, Darjeeling Government College, Darjeeling, India

The nuclei of the male and female gametocytes of the malarial parasites (Plasmodium and Hepatocystis) are Feulgen-negative, while the nuclei of the gametocytes of Hepatozoon, which are not sexually differentiated, are Feulgen-positive. The nuclei of the male gametocytes of Eimeria are strongly Feulgen-positive, while the nuclei of the female gametocytes are Feulgen-negative. The nuclei of the male gametes of Plasmodium are Feulgen-negative, while the nuclei of the male gametes of Eimeria are strongly Feulgen-positive. DNA appeared to be present in the gametocytes of Plasmodium when the fluorescence method of Armstrong (1956) was employed.

Feulgen-positive inclusions have been found to occur in the cytoplasm of some of the oöcysts of Plasmodium. The oöcysts containing such inclusions may degenerate totally or partially. There is no evidence to relate this type of degeneration with the formation of Ross's black spores. These inclusions have been found in abundance in the oöcysts of P. cynomolgi, while in those of P. gallinaceum they were found only once.

Certain Feulgen-positive granules have been found in the cytoplasm of some of the oöcysts and the female gametocytes of Eimeria. These granules did not appear to be related to any degenerating changes. A probable loss of some of the nuclei during sporogony of Eimeria is discussed.

The nuclei in the early pre-erythrocytic schizonts of Plasmodium cynomolgi are Feulgen-positive, notwithstanding an earlier report to the contrary.