THE PARASITIC PROTOZOA OF THE RED GROUSE 321 



are designated females. The females or macro-gametocytes, which measure 1 4~ to 

 20^ by 10^ to 16m, appear to be somewhat more numerous than the males or 

 micro-gametocytes, which are about IS^ix to 17^ by 6/m to 12^. The nuclei of the 

 gametocytes are not well marked, even after long staining. The nucleus of the 

 micro-gametocytes (Figs. 4, 9, 13) is often somewhat larger than that of the 

 macro-gametocyte (Figs. 6, 10, 12), is ill-defined (Figs. 11, 13, 14) in contour, 

 and frequently has small granules of chromatin scattered within it (Figs. 11, 14). 

 The macro-gametocyte has a better defined nucleus (Figs. 6, 10, 12), in which a 

 larger granule of chromatin — a karyosome — is sometimes present (Figs. 5, 6, 10). 

 Small chromatoid granules are often seen at either pole of the gametocytes (Figs. 4, 

 11, 13), sometimes more numerous at the ends of the micro-gametocytes (Figs. 4, 

 9, 11, 13) than at the ends of the macro-gametocytes (Figs. 10, 12). These chrom- 

 atoid granules are, I think, more probably derivatives of the nucleus of the host-cell 

 in process of absorption by the parasite than actual chromidia within the parasite, 

 for sometimes the chromatoid granules are clearly outside the parasite (Figs. 6, 7). 



The details of the maturation of the female gametocyte to form the macrogamete 

 are little known — probably the macro-gametocyte becomes the macrogamete with 

 little or no cytological change. Danilewsky (1890) and Sakharoff (1883-1885) 

 described the formation of flagella-like microgametes from the hyaline micro-game- 

 tocyte in/res/i, preparations of the blood of certain owls, crows, and rooks. The 

 microgametes (males) of Z. ziemanni were considered by Schaudinn (1904) to be 

 formed normally in the mid-gut of a mosquito which sucks the blood of the avian 

 host (an owl). The more recent observers of avian Leucocytozoa have not usually 

 seen gamete formation in the fresh state, so far as can be gathered from their 

 published accounts. 



Mathis and Leger (1909) have recently made the very interesting statement 

 that there is a periodicity in the occurrence of the gametocytes of L. caulleyri in the 

 blood of the fowls they investigated at Tonkin. The events of the life-cycle of the 

 parasites in the period intervening between their appearances in the blood are un- 

 known. There seem to me to be several alternatives possible, either the parasite 

 undergoes a multiplicative stage in some internal organ (though it is stated that the 

 internal organs of the fowls were examined), or a latent phase without increase in 

 numbers of the parasite occurs, or else a re-infection of the host takes place. I 

 have found schizogony of L. lovati (see p. 322) in the spleen of the host, but so far 

 neither time nor material have been available for my observing any possible 

 periodicity in the gametocytes of L. lovati, though such may occur. 



VOL. I. 



