THE H^MOFLAGELLATES. 219 



The occurrence of prominent myoneraes in the undulating 

 membrane of Trypanomorpha, and tlieir nuclear origin (as 

 " mantle-fibrils ") has been above described, Schaudinn finds 

 a like development in Trypanosoma ziemanni^ the fibrillae 

 being particularly noticeable in the male and female forms 

 (fig. 33). In this parasite, however, tliey are not restricted 

 to the undulating membrane, but are arranged laterally, half 

 running down each side of the body, in the ectoplasm. Their 

 total number is sixteen, corresponding to the number of 

 chromosomes. According to Prowazek an exactly similar 

 state of affairs exists in both T. lewisi and T. brucii, 

 although the myonemes (of which there are here eight) are 

 very delicate and difficult to make out. In two or three 

 other forms longitudinal striations, comparable to muscle- 

 fibrilla3, are well-marked ; nothing is known, however, with 

 regard to their origin. Thus in Try panoplasma borreli 

 there are two, which start in front, sweep round, one on each 

 side of the body, and run backwards more than half-way, 

 finally joining ventrally (fig. 18 c, /.). The myonemes are 

 very prominent in the ribbed^ forms of T. rotatorium (fig. 

 17 b), in which the surface of the body is thrown into longi- 

 tudinal folds or ridges, often having a somewhat spiral course 

 (56 a) ; the striations appear to lie in the furrows between the 

 ridges. In T. solese, again, the longitudinal sti'ise are dis- 

 tinctly discernible (fig. 17 j) ; and Novy and McNeal (81) 

 record the occurrence of six or eight in T. avium. 



Section VII. Biological Considerations ; Movement ; 

 Agglomeration; Abnormal and Involution Forms. 



(a) Movement. 



In general Trypanosomes are extremely active, as would 

 naturally be expected from their powerful locomotor organs. 



' Other individuals, distinguished as smooth forms (figs. 17 A, 56 b), do 



not show them. 



