712 



ORDER: DIPLOMONADIDA 



this region in such a way that one edge is folded forwards and the other 

 backwards. An organism viewed from the anterior or posterior end has 

 the appearance of an S, the hollows of the letter corresponding with the 

 grooves. Running round the anterior end of the body is a horseshoe- 

 shaped structure tapering at its extremities, which lie at the commence- 



FiG. 299. — Trepomonas agilis as a Coprozoic Flagellate in Human F,eces 

 (x 3,000). (After Wenton and Broughton-Alcock, 1924; from Trans. 

 Boy. Soc. Trop. Med and Hijg., vol. xviii., p. 9). 



1. Form with narrow groove. 



2. Form with gaping groove with turned-out edges producing impression of lobes. 



3. Early division form. 



ment of the grooves. Within this structure can usually be distinguished 

 four deeply-staining granules. Two of these lie near one another at the 

 anterior end of the body, while the others are nearer its extremities. 

 Arising from a point near the commencement of each groove are a number 

 of flagella. One of these is a conspicuous long flagellum directed outwards, 

 while the others are short and lie in the groove. 

 There appear to be three short flagella, but it is 

 not always possible to distinguish this number. 

 Klebs figured a long flagellum and three short ones. 

 The nature of the horseshoe structure is doubt- 

 ful. In dividing forms it splits into two, and one 

 half moves to the opposite end of the body. 

 Before it divides, however, division of the granules 

 within it takes place, so that it is possible that 

 the two anterior granules which are surrounded by 

 a clear area are the true nuclei, the other two 

 granules blepharoplasts, and the structure itself a 

 parabasal. The organism would appear to be re- 

 lated to Hexamita, the six short flagella in the grooves corresponding with 

 the six anterior flagella and the two long ones with the posterior flagella. 



Fig. 300. — Trepomonas 

 sp. from Eectum of 

 Marine Fish, Box 

 salpa ( X 2,250). 

 (After Alexeieff, 

 1910.) 



