A New Malaria Parasite of Man. 



377 



(1) Its bulk is much less, i.e. it is a smaller parasite. 



(2) The amoeboid -processes are far more delicate. 



(3) The chromatin shows a relative abundance, an irregularity and a 

 peculiarity of arrangement {e.g. strands, rods and bars) not seen in the 

 simple tertian parasite. 



(4) Typical rings are absent or exceedingly rare. 



I am not sure whether this parasite enlarges the cell, as, although in some 

 cases I found infected cells larger than non-infected ones in their vicinity, 

 in other cases the reverse held good. I am uncertain also whether it is 

 pigmented or not. I have found no parasites in which I could certainly 

 detect pigment ; but, on the other hand, I found three pigmented leucocytes 

 in the film, which leucocytes may be associated with this parasite or may 

 result from an associated infection. Finally, I am in doubt as to whether 

 it produces any change in the red cell such as Schunher's dots. During 

 the course of my examination of this film I must have observed many 

 thousand parasites, but among these I encountered only one infected cell 

 which was clearly enlarged and which showed Schuffner's dots. The bulk 

 of this parasite was much greater than that of any other I had seen, 

 whereas the chromatin masses (two in number, one large, one small) were 

 small compared to the bulk of the parasite. Although I could detect no 

 pigment in this parasite I was not otherwise able to distinguish it from a 

 simple tertian parasite.* These points then must remain unsettled until 

 further material is forthcoming. 



Quartan. — Its amoeboid activity and its tenuity easily distinguish it from 

 this species. 



After a prolonged study of this parasite I believe then that its morphology 

 differentiates it from any malaria parasite of man yet described. 

 I propose to call it Plasmodium tenue. 



DESCRIPTION OF PLATES. 



The figures were all drawn with an Abbe camera lucida at the same magnification, 



x 2300 (approx.). 



Plate 14. — Plasmodium falciparum. Blood slide from Rhodesia ; 35 parasites drawn at 

 random. 



Plate 15. — Plasmodium tenue. Blood slide from Central Provinces, India ; 35 parasites 

 drawn at random. 



Plate 16. — Plasmodium tenue. Illustrating the irregularity of form of this parasite. 



* I incline to the view, however, that this large form belongs to the other irregular 

 forms, and hence that this parasite enlarges the cell and produces a stippling in it, 

 and hence also that it has affinities with the simple tertian parasite, and Plasmodium 

 canis of the dog rather than with the malignant tertian parasite. 



