548 Protozoa of the Digestive and Urogenital Tracts 



to pear-shaped and contains one nucleus; nuclear division apparendy does 

 not occur (17). 



Tricercomonas intestinalis 

 Wenyon and O'Connor 



This species may or may not be identical with Enteromonas 

 hominis Fonseca. This question has been discussed by Dobell and 

 O'Connor (52) and by Wenyon (178), and the latter has pointed out that 

 Enteromonas hominis was described with only three flagella. 



Flagellated stages (Fig. 11. 2, A, B) have three anterior flagella and a 

 fourth which may seem to lie within the cytoplasm and emerge at or near 

 the posterior end of the body. The size range is 4-10 x 3-6[j.. The cysts 

 (Fig. 11. 2, C-E) measure 6-8 x 3-4[x and contain 1-4 nuclei (22). A flagel- 

 late apparendy identical with T. intestinalis has been found in mon- 

 keys (46). 



Chilomastix mesnili 



(Wenyon) Alexeieff 



This flagellate (Fig. 11. 2, J-O) seems to be specifically identical 

 with one in apes and monkeys (64). The active stage, 6-20|x in length, has 

 three anterior flagella and a shorter fourth which usually lies in the cyto- 

 stomal groove, a depression extending obliquely from near the anterior 

 end to about the middle of the body. A second groove often arises near 

 the left anterior margin of the cytostomal cleft and extends posteriorly 

 in one or two spiral turns. Solid food is ingested through a cytostome at 

 the posterior end of the cytostomal groove (178). Just beneath the 

 surface, a cytostomal fibril of uncertain significance extends along the 

 cytostomal groove. Fission has been described by Geiman (64) and by 

 Boeck and Tanabe (24). 



Encysted stages (Fig. 11. 2, N, O) measure 7-10 x 4.5-6.0jx, contain one 

 or two nuclei, and often granules and fibrils representing the blepharo- 

 plasts, cytostomal fibrils and possibly flagellar axonemes. Mitosis has 

 been described in encysted stages (67, 100). 



Pentatrichomonas hominis 



(Davaine) Kirby 



Two flagellates from the human colon are described in the litera- 

 ture as Tridwmonas hominis (Davaine) Leuckart, with four anterior 

 flagella, and Hexamitus ardin-delteili (44), later transferred to the genus 

 Pentatrichomonas (103, 105) on the basis of its fifth free flagellum. In 

 confirming observations of Wenrich (171), Kirby (91) concluded that 

 T. hominis normally has a fifth free flagellum and that the two sup- 

 posedly distinct flagellates should be recognized as Pentatrichomonas 



