210 H. M. WOODCOCK. 



cytoplasm by taking a slightly different tint; and Prowazek, 

 in his recent work on this parasite, remarks to the same 

 effect. In Trypanophis, Keysselitz (28) finds a prominent, 

 highly-refractive, and finely-alveolar ectoplasmic layer, 

 especially well developed near the anterior end, where it forms 

 a little cap (fig. 41, ex.). Unfortunately, even now very few 

 direct references to the subject are available. 



It appears most likely that the undulating membrane is 

 largely, if not entirely, an ectoplasmic development. This is 

 usually clearer, more hyaline, and less granular than the rest 

 of the cytoplasm, and in these characters it agrees with a 

 typical ectoplasm. The fact, too, that it is so closely asso- 

 ciated with locomotion supports this view.^ Similarly, with 

 regard to an ectoplasmic differentiation surrounding the body 

 generally, the occurrence of distinct, superficial, longitudinal 

 strige, probably comparable with myonemes (see below, p. 219), 

 points to the existence of such a layer, since myoneme 

 fibrillas, when they occur, are always situate in the ectoplasm. 

 Dutton and Todd (1. c.) found that, in injured individuals of 

 T. mega, a delicate membranous (?) envelope, continuous 

 with the undulating membrane, could be easily separated 

 from the rest of the body. In it were fine, pink-staining 

 lines, having a looped arrangement. There can be little 

 doubt this structure was an ectoplasmic sheath with myoneme 

 striations. In short, it seems probable that, in the majority 

 of Trypanosomes, there is such a layer around the body, 

 although, apparently, often poorly developed and ill-differ- 

 entiated when compared with the undulating membrane. 



The general cytoplasm may be of a clear, finely granular, 

 or alveolar nature, presenting a fairly homogeneous appear- 

 ance, as in T. lew is i, T. equip erdum, and T. gambiense 

 (some individuals), although even in these cases it rarely 

 stains up quite uniformly. It may be coarser and relatively 

 dense, as in T. avium, T. rajae, T. scyllii (fig. 62), and 

 others. The cytoplasm of male forms is, in general, much 

 clearer and less granular than that of female forms. Accord- 

 * Cf. also its formation in Trypanomorpha (p. 186). 



