natural, history

Microgametocytes have a diffuse or somewhat saddle-shaped nucleus which stains avery light link, and their cytoplasm does not react to Giemsa and appears paler thanthe surrouneing cytoplasm of the host cell. Their round to oval pigment granules,which reach a rather larger size than do those of the females, become bunched at theextremities and number from 13 to 30 (av., 23). Macrogametocytes (Figs. 9-13) aremuch more abundant than male parasites. Their small and compact nucleus isrounded to elongate-oval, stains deep red, and contains a prominent karyosome whichassumes a still deeper red shade. The alveolar cytoplasm is coloured bright blue byGiemsa. A characteristic feature is a large and prominent vacuole - the site wherepigment was initially deposited? - which may attain a diameter of 2.5 fL. From 21 to43 (av., 33) pigment granules are scattered throughout the body.Large macrogametocytes very often all but surround the host cell nucleus (Figs.10, 11), and sometimes their extremities meet and fuse so that the nucleus is completelyengulfed (Fig. 12). Until this stage the parasite and the nucleus are seldom in actualcontact, but thereafter there is no sign of a gap between them. The length. measuredalong the midline, reaches 28.5 fL in the case of males and 29.5 fL in that of females.Examples which have pushed the host cell nucleus to the periphery may be as muchas 7fL in width.Two parasites may develop within one erythrocyte. finally completely filling thes~ace between the nucleus and membrane of the host cell. and losing all sign of thei rindividual identity (Fig. 13). When two macrogametocytes are associated in this way,their nuclei are usually conspicuous. The true nature of the invasion is also revealedby the occurrence of two large vacuoles instead of one, and of double the usualnumber of pigment granules. Occasionally parasites of opposite sexes jointly occupya red cell. The phenomenon is not uncommon among haemoproteids. BRUMPT (1935)illustrated avian erythrocytes completely filled by two gametocytes of various species.and figured the apparent intraer)throcytic fusion of male and female gametocytes ofHaemoproteus aluci Celli & San Felice and H. tinl1unculi Wasielewski & Wiilker.Like Trypanosoma. Haemoproteus includes a large number of species describedsolely on the basis of their occurrence in new hosts and localities. In all but a fewinstances stages other than gametocytes - which alone occur in the peripheral circulation- are unknown.Fully developed gametocytes are usualiy elongate and more or less halter-shaped.but sometimes - and perhaps more frequently than would appear from the literature- they completely engulf the host cell nucleus. COATNEY & ROUDABUSH (1937)pointed out that earlier literature indicates that the host cell nucleus becomes sur·rOlV'ded by gametocytes of H. danilclfSkii Kruse. H. fringillae Labbe and H. maccalfum;Novy & MacNeal. These authors, however. asserted that the first two species••never completely fill the space between the nucleus and limiting membrane of thehost cell, and stated that. contrary to the original description. gametocytes of H.maccal/um; do not fully encircle the host cell nucleus. The Rennell parasite is thusnot referable to any of these species nor to a more recently described one. H. halcyon;_