HJEMOSPORID1A 



153 



blasts) in the blood of birds. Laveran and Franga consider that 

 the Leucocytozoa occur in erythrocytes. The host cells are often 

 greatly altered by the parasites, becoming hypertrophied and the ends 

 usually drawn into horn-like processes (fig. 77), though some remain 

 rounded. Leucocytozoa are limited to birds, and very rarely produce 

 pigment. Male and female forms (gametocytes) are distinguishable 

 in the blood (fig. 77), and the formation of male gametes ("ex- 

 flagellation ") may occur in drawn blood. 



The Leucocytozoa were first seen by Danilewsky in 1884. They 

 are usually oval or spherical. It is not easy sometimes to distinguish 

 the altered host cell from the parasite, as the nucleus of the former 



is pushed to one side by the 

 leucocytozoon. The cyto- 

 plasm of the female parasite 

 stains deeply, and the nucleus 

 is rather small, containing a 

 karyosome. In the male the 

 cytoplasm stains lightly and 

 the nucleus is larger, with a 

 loose, granular structure. 



Many species of Leuco- 

 cytozoa are recorded, but 

 schizogony has only been 

 described by Fantham (i9io) T 

 in L. lovati in the spleen of 

 the grouse (Lagopus scoticns), 

 and by Moldovan 2 (1913) in 

 L. zieinanni in the internal 

 organs of screech-owls. 



M. and A. Leger 3 (1914) 

 propose to classify Leuco- 

 cytozoa, provisionally, according as the host cells are fusiform or 

 rounded. 



(4) The Hcemogregarina type. Included herein are many parasites 

 -of red blood corpuscles, with a few (the leucocytogregarines) parasitic 

 in the white cells of certain mammals and a few birds. They are not 

 amoeboid but gregarine-like, vermicular or sausage-shaped (fig, 7^). 

 They do not produce pigment. They are widely distributed among 

 the vertebrata, but are most numerous in cold-blooded vertebrates 

 (fishes, amphibia and reptiles). The haemogregarines of aquatic hosts 

 are transmitted by leeches, those of terrestrial hosts by arthropods. 



1 Annals Trap. Med. and Parasitol., iv, p. 255. 



2 Centralbl.f. Bakt., Orig., Ixxi, p. 66. 



3 Bull. Soc. Path. Exot., vii, p. 437. 



^> A 



FIG. 77- Leucocytozoon lovali. a, Male parasite 

 (microgametocyte), within host cell, whose ends are 

 drawn out ; b, female parasite (macrogametocyte) 

 from blood of grouse. X 1,800. (After Fantham.) 



