710 MISS ANNIE PORTER ON A [June 16, 



able to turn freely somewhat in the fashion of Nyctoiherus. 

 The anterior end remains still, but the posterior part of the 

 body turns over so that the upper surface becomes folded over 

 the under, which, at the distal end, is now uppermost. The line 

 of folding is somewhat oblique. Reversal of this movement 

 ■occurs, and the organism appears to roll from side to side as a 

 result of the combined movements. 



Accompanying this movement there is a second. One sur- 

 face of the body of the parasite contracts, and as a result, the 

 ends of the body approximate somewhat more closely to one 

 another than before. Relaxation follows, and the body straightens 

 with a jerk which has the effect of forcibly propelling the 

 organism forwards. 



The path of the organism is never straight. Movement appears 

 to be initiated at either end indiffei'ently. The path is often very 

 restricted and the organism remains for long periods at practically 

 the same spot, though one of its ends ujay have vibrated in 

 practically every direction. 



VII. Detailed Morphology. 



(a) The Trophozoite. 



Ectoplasm. — In the trophozoite this is not markedly differentiated. 

 It appears as a somewhat clearer portion in some specimens. 

 Contractile elements or myonemes are present, arranged in longi- 

 tudinal rows. These myonemes are very evident in some specimens 

 (PI. XXXIX. figs. 7, 11) and often are well seen in the region of 

 the nucleus. A refractile cytocyst is often present, and when 

 this is well marked, a clear space usually intervenes between 

 it and the ectoplasm (PI. XXXIX. figs. 8, 9, 10, 11, 12). The 

 cytocyst is always thin and membranous. 



Endoplasm. — This is richly granular (PI. XXXIX. figs. 1, 4) 

 and the granules react vigorously towards stains. In some speci- 

 mens the endoplasm appears almost alveolar (PI. XXXIX. fig. 12) 

 owing to the disposition of the granules in regular networks. 

 There are concentrations of granules beneath the myonemes 

 and also in the region of the nuclear membrane. Frequently a 

 relatively clear space appears near one end, almost suggestive of a 

 large vacuole (PI. XXXIX. figs. 3, 4, 7, 21). In a few specimens 

 isolated chromatic granules are present (PI. XXXIX. fig. 8). 

 The latter do not seem to have any direct connection with the 

 nucleus. 



Nucleus. — This is circular or oval, approximately centi'al in 

 position or sometimes nearer to one end and possesses a definite 

 nuclear membrane. Its chromatin is diflfusely spread within and 

 much achromatic substance is present. The structure of the 

 nucleus may best be described as vesicular. There does not 

 appear to be a karyosome as described by James [10] in one of his 

 forms of Leucocytozoon cards. In its general structure and 

 behaviour towards stains, the nucleus of this parasite is very 

 suggestive of that of Trypanosoma rajce. 



