256 SCIENCE PROGRESS 



chromatin may be present in the form of grains as in L. muscuh 

 (figs, i, d; 3, c), or, as in L. muris (fig. i, c), it may extend across 

 the breadth of the nucleus in the form of strands, or the 

 chromatin may form a fairly compact mass, such as may be 

 seen in L. canis (fig. i, a). The general outline of the nucleus 

 is oval or round, its breadth is sometimes that of the parasite 

 (fig. i, c), or may be slightly less (figs, i, a, b, d ; 3, b, c). In no 

 case is it easy to stain the nucleus, for the outer layer of 

 ectoplasm is difficult of penetration by stains. 



Chromidia, or extra-nuclear grains of chromatin, are found 

 in some Leucocytozoa. For instance, preparations of L. musculi, 

 stained with Giemsa's stain (alkaline methylene blue and eosin), 

 show areas or caps of a red (chromatin) colour at either end. 

 Isolated chromatic granules also are present (fig. 3, c), occurring 

 in various positions in the body of the organism. L. funambuli 

 also exhibits this feature well, scattered groups of chromatin 

 granules being found near the ends of the parasite (fig. i, b). 

 Chromidia are migratory in nature, and pass out from the 

 nucleus into the general protoplasm, where their presence is 

 often associated with great metabolic activity of the organism. 



The exact structure of the Leucocytozoa of birds is still a 

 matter of some controversy. The most recent account is that 

 of Wenyon (1908), who agrees that the host-cell may, in some 

 cases, be drawn out into a long, spindle-shaped body (fig. 1, e). 

 In size the gregariniform parasites may be 40 fx to 60 /x long by 

 5 /x to 8 /x broad. The Leucocytozoa of birds are thus larger than 

 those of mammals. Of these avian Leucocytozoa, those forms 

 which have markedly granular protoplasm, and are somewhat 

 larger, have been considered female mother forms, while the 

 smaller parasites with few protoplasmic granules have been 

 considered to be male mother cells. The female (gamete) forms, 

 arising from the female mother cells, are usually round, while 

 the male gametes are small, thin, and flagella-like. Undoubted 

 fertilisation has, however, been described very rarely — at any 

 rate from observation of the living organisms. 



The best known of the amphibian Leucocytozoa is L. ranarum, 

 described by Carini in 1907, from the blood of Leptodactylus 

 ocellatuSy a South American frog. The parasite is large, being 

 from 30 ix to 40 ix long and from 10/1. to 15 /x broad. No trace of 

 differentiation of gametes was seen by Carini in this parasite. 



