254 SCIENCE PROGRESS 



tn advance steadily by an outflow of the cytoplasm, which 

 outflow i: r*S easily La as the protoplasm is ^ichly granular 

 and stains easily intra-vitam with methylene blue. 1 he parasite 

 now ies nearer the nucleus of the leucoeyte, and the nucleo- 

 plasm appears in a state of agitation. The parasite grows 

 ranidlv durins: this period (fig. 2, a-d). 



The gliding movement of the parasite continues and the 

 nucleus of the leucocyte becomes altered in shape until at times 

 rappears as a lens-shaped mass, lying within the horns of a 

 crescent formed by the parasite (fig. 2, d, e). 



The urther forward motion of the Leucocytozoon results 

 frequently in one end becoming much larger than the other and 

 a comma-like appearance ensues (fig. 2, f-k). The posterior 

 end appears somewhat " tail "-like and filamentous unde 

 these circumstances, but this is due to the turning of the 

 Leucocytozoon on its side, thereby exposing its edge only 



(fig Wne J n the young parasite has assumed the "comma" form 

 a vesicle often appears, usually towards the broader end of the 

 organism fig. 2, r). The Leucocytozoon remains much the same 

 KTfor some time, but changes occur in the vesicle, in which 

 small chromatin masses begin to differentia e (fig. 2, G-K> 

 Gradually however, concentration of the protoplasm occurs and 

 the "comma" shape gives place to a somewhat bowed, reniform 

 'body, I which the P ve e s,cula P r nucleus lies 1 somewhat ^nearer one 

 end than the other. When the parasite has reached this stage 

 the host-cell commences to react upon it, and a cytocyst or 

 ,°U nrnduced ffig I, d) within which the Leucocytozoon 

 rents^TttrSsm Jay continue -tionless for some 

 long time, probably days, but its extrusion either with (fig. 3, c) 

 or without (fig. 3, a, b) its cytocyst, usually occurs 



Extrusion of the parasite is brought about by internal 

 pressure The Leucocytozoon moves forward w th a slow, 

 gSng movement, which continues until extrusion is com- 

 pleted There is slight resistance at the periphery of the 

 Feucocvte but the parasite presses outwards, carrymg a small 

 column of the protoplasm of the host-cell at its sides. When 

 it has passed out from the leucocyte, the point of exit closes 

 and" invisible, but the parasite often remains in W 

 of its host-cell, in a practically quiescent condition, for some 



