STUDIES ON AVIAN HiEMOPROTOZOA. 729 



described. He also figures a young Leucocy tozoon in a 

 cell which obviously corresponds to the uninucleate leucocytes 

 (cf. his fig. 4 with my figs. 24 and 60), But he does not 

 figure the true type of host-cell (uninfected) at all ; this, I 

 gather, he considers to be an immature red cell, such as he 

 figures. I have no hesitation in saying — what, indeed, is 

 appai*ent from my figures — that the uninucleate leucocytes 

 (fig. 23) are the host-cells, and not immature red cells or 

 erythroblasts (fig. 22). 



Effects on the Host-cell. — The young Leucocy to- 

 zoon always penetrates the leucocyte on the side where 

 there is most cytoplasm. It never becomes actually intra- 

 nuclear, but it often has a curious position in relation to the 

 nucleus during its early growing phases, appearing to be 

 lodged in a deep depression or pit in the side ot" the nucleus 

 (fig. 62). At times the parasite is almost entirely enclosed 

 by the nucleus (fig. 19). This result is probably due partly 

 to a tendency of the Leucocytozoon to push or sink further 

 inwards, and partly to the growing out or extension of the 

 nucleus, which undergoes a certain amount of hypertrophy, 

 in the form of a wide crescentic or semi-circular mass, at 

 the sides of the parasite. Coincideutly, the nucleus under- 

 goes an alteration in character, losing all indications of large, 

 separate chromatic masses, and taking up the stain quite 

 uniformly. As the parasite grows and expands, the free ends 

 of the semi-circular nucleus are pushed outwards, and no 

 longer enclose the Leucocytozoon. When the latter is 

 full grown the nucleus of the containing host-cell is seen as a 

 thick, curved mass at one side (figs. 20, 21, 25, and 26). 



In my preparations all the leucocytozoa are intra-cellular. 

 I have never observed more than one parasite in one host- 

 cell. 



My observations, as also those of Wenyon (I.e.), of young 

 and intermediate-sized gametocytes, intra-cellular in habitat, 

 and manifestly growing into the adult individuals in a 

 similar situation, do not support in the least Schaudinn's 

 view with regard to the origin of the adult gametocytes. 



