THE LEUCOCYTOZOA 



255 



V. Comparative Morphology 



In most species of Leucocytozoa the outer layer, or ectoplasm, 

 of the body is clear, smooth, refractile and difficult to stain. 

 Differentiation of the ectoplasm is rarely seen, but L. musculi 

 has myonemes passing down the entire length of its body 

 (fig. 3, b), and these have a bead-like appearance in life. A 

 refractile cytocyst is also recorded in some (fig. 3,c) ; probably it 

 is secreted by the leucocyte around the invader. In such cases 

 a clear space may be present between the ectoplasm of the 

 parasite and the cytocyst (fig. 1, d). 



The endoplasm is always richly granular and stains deeply. 



wsyn 



Fig. 3. — Vermicular forms of Leucocytozoa. 



A, L.funambuK (after Patton). Fresh preparation. Parasite attenuate and curled up at one end. Nucleus 

 appears as a clear, central spot, u, L. musculi (after Porter). Free parasite showing myonemes. 

 Protoplasm vacuolated. Nucleus almost central, c, L. musculi (after Porter), showing cytocyst 

 around the free parasite. Extra-nuclear chromatin granules (chromidia) are seen in a group in the 

 cytoplasm above nucleus. D, L. musculi (after Porter). Free vermicule with pointed end, from the 

 gut of the louse, H&matopinus spinulosus. 



In many cases the granules are evenly distributed throughout 

 the endoplasm, but in L. musculi slight concentration of the 

 granules occurs beneath the myonemes. A clearer area 

 suggestive of a vacuole is also present in some specimens of 

 L. musculi (fig. 3, b, c). 



The nucleus is either of the vesicular type, as in L. musculi 

 (figs. 1, d ; 3, b), or is fairly compact in character as in L. cams 

 (fig. 1, a). A nuclear membrane is present, and is denser in forms 

 of the parasite with vesicular nuclei. The part of the nucleus 

 that stains more deeply is termed chromatin. The nuclear 



