372 



3- Further observe that polynuclear leuco- 

 cytes contain only one or two of these bodies 

 (Fig. i6);' large mononuclear leucocytes one to 

 six (Fig. 17) ; cells of an endothelial type one to 

 twelve (Fig. 18) ; large cells with a hyaline or 

 finely' granular or vacuolated cytoplasm (macro- 

 phages) up to several hundreds (Fig. ig). 



4. The parasites are approximately circular 

 or oval, 2'5-3'5 m in size, clearly outlined, and 

 appear to possess a distinct cuticle, as they retain 

 their shape and are rarely seen distorted in films. 



5. The two chromatin masses are character- 

 istic, the large one staining lightly and the small 

 one intensely with Romanowsky. The masses are 

 usually situate opposite each other in the short 

 axis of the parasite. The larger chromatin mass 

 always forms part of the periphery of the parasite. 



6. Most of the parasites contain one or two 

 vacuoles which may displace the cytoplasm of the 

 parasites to the periphery. 



7. Developmental forms. Division com- 

 mences at the thick end of the parasite, and the 

 large chromatin masses may be widely separated 

 before the small chromatin mass has begun to 

 divide. As many as three to six bodies are formed 

 in this way, the large nuclei being arranged peri- 

 pherally, and the smaller centrally (Figs. 7- 11). 



Occurrence in Peripheral Blood 



In two cases only, approaching a fatal 

 termination, have we found parasites in the peri- 

 pheral blood. The parasites were of the typical 

 structure, but were all included in leucocytes. 

 During a count of five hundred leucocytes we 

 counted altogether thirty-seven parasites. 



