260 H. M. WOODCOCK. 



bably^ uut limited by any distinct cuticle or membrane^ The 

 cytoplasm is finely granular and fairly uniform in character 

 (Rogers^ Laveran and Mesnil) ; in some of Donovan's 

 figures there is a faintly stained or clear area of varying 

 size, more or less centrally situated, which possibly repre- 

 sents a vacuole." The most interesting point in the 

 morphology of these bodies is the fact that two chromatic 

 masses, of very unequal size, are invariably to be recognised, 

 except in very young forms. The larger nuclear mass, 

 which, it may be at once said, is in all likelihood homologous 

 with the trophonucleus of a Trypauosome, is usually round 

 or oval,^ and varies in position ■ in the pyriform parasites it 

 is generally situated near the basal end, and in the oval ones 

 about the middle of one side. The smaller nuclear body 

 (representing, probably, a kiuetonucleus) stains more in- 

 tensely, and takes the form either of a little rod (sometimes 

 curved) or of a round dot or grain. It is generally quite 

 separate from the larger nucleus. In the round or oval 

 parasites it is on the opposite side of the body and at the 

 periphery; in the pear-shaped forms it is about the middle 

 of the length or nearer the narrow end (fig. 37 I).^ In some 



^ Ross (140, 141) considers that the free forms, at any rate, possess a 

 distinct and resistant cell-wall or cuticle, comparable to a spore membrane. 

 Christophers at first thought so too, but in his later Report appears to be 

 doubtful, in view of the non-resistance of the bodies and their rapid break 

 up after the death of the host. 



^ Both Christophers and Wright represent the bodies as having only a 

 narrow peripheral border of stainable cytoplasm, all the central part 

 remaining unstained, and constituting (according to Christophers) one or 

 two huge vacuoles. These authors have probably been misled by deceptive 

 appearances due to staining peculiarities, which have, unfortunately, led 

 them to an incorrect interpretation of the bodies (see below, p. 2G3). 



^ In some cases it is heart-shaped or bilobed, probably indicative of 

 approaching division. 



■• These different forms and appearances are explainable, as Christophers 

 points out, by regarding the parasite as viewed from different aspects, 

 e. g. end-on or sideways. This may, very likel}', often be the case, the 

 typical form being that of a slightly llattened pear. There is no necessity, 

 however, to consider the body as having a fixed and unchangeable shape. 



