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A New Malaria Parasite of Man. 



By J. W. W. Stephens, M.D., Sir Alfred Jones Professor of Tropical 

 Medicine, University of Liverpool. 



(Communicated by Sir E. Eoss, K.C.B., F.E.S. Eeceived January 19, — 

 Eead February 19, 1914.) 



[Plates 14-16.] 



In the autumn of 1913 Major Kenrick, I.M.S., kindly sent me, from 

 Pachmari, Central Provinces, India, a blood slide from a native child, 

 containing numerous malaria parasites. On examining these, which I at 

 first took to be malignant tertian parasites, the suspicion arose in my mind 

 that there was something peculiar about their appearance. I happened just 

 previously to have been studying a blood slide from Ehodesia, containing 

 very numerous malignant tertian parasites. The peculiarity of the Indian 

 parasite, as far as I could at first define it, was that it was an irregular 

 parasite as compared with the regular, almost monotonous, contour of the 

 "rings" of the malignant tertian parasite (Plasmodium falciparum). I 

 proceeded then to study the Indian parasite more carefully ; and, after daily 

 observations for many weeks of it, and of control malignant tertian 

 parasites from various sources, I came definitely to the conclusion that it 

 was unlike any malignant tertian parasite that I had ever seen or that I 

 could find figured in the text-books or journals. I also considered carefully 

 the possibility of its being the simple tertian parasite, but to this point I 

 shall return later. During this study, in order to fix my impressions, I drew 

 150 consecutive parasites from the Indian slide and the Ehodesian slide 

 respectively, as the former appeared in the field of view of an ocular so 

 restricted by placing a diaphragm in it that only half a dozen red cells were 

 visible in the field at a time, thus effectively preventing any selection on 

 my part. I reproduce as pen-and-ink drawings 35 of each series taken at 

 random, as they show very well in a general way the different aspect of 

 the two parasites. For the same purpose I also drew a number of young 

 simple tertian parasites. 



I now proceed to define as far as possible in detail the peculiarities of 

 this parasite. 



1. It is extremely amoeboid (judging from the stained specimens). Thin 

 processes often extend across the cell or occur as long tails to more or less 

 ring-shaped bodies. These processes may be several in number, and may 



