PART II.^-CIIARACTERS AND DIAGNOSIS 89 



within the cyst, though the exact significance of the appearances 

 are doubtful. The nuclear membrane becomes much elongated 

 and may stretch from one end of the cyst to the other, while the 

 karyosome tends to become dumb-bell shaped and divided into 

 several parts. Whether this is an indication of nuclear multiplica- 

 tion cannot be stated at present (Plate IV, figs. 15 to 20).* 



The flagellate which has just been described from two cases 

 has never been encountered before, and is evidently a new parasite 

 of the human intestine, and for this reason we have given it the 

 name Waskia intestinalis, after the Orwa-el-Waska section of the 

 19th General Hospital where it was first discovered. 



(21) Tricercomonas intestinalis, n. g., n. sp. 

 (Plate III, figs. 1 to 11.)* 



The small flagellate which we have found in about a dozen cases 

 differs entirely from WasJcia intestinalis already described. It is 

 a small active organism which is very difficult to study on account 

 of its rapid dancing movements. It has a spherical or ovoid body 

 which is distinctly flattened on one side as in flagellates of the 

 genus Cercomonas. The posterior end is drawn out and terminates 

 in a flagellum which can be traced forwards along the flattened side 

 to the anterior end of the body where three other long flagella 

 originate. The tail flagellum appears to be attached to the surface 

 of the body, and occupies this position in all the active movements 

 of the organism. For this reason it seems clear that the flagellum 

 is actually attached to the surface of the body and not merely 

 applied to it as Woodcock thinks is the case in cercomonas, where 

 the tail flagellum is similarly arranged. In the tricercomonas as 

 well as cercomonas the cytoplasm of the body is drawn out into 

 a tapering process which follows the flagellum for some dis- 

 tance, and it seems difficult to understand how this can be if the 

 flagellum is merely applied to the body and not definitely attached. 

 The posterior flagellum of tricercomonas and cercomonas is attached 

 to the surface of the body as much as the flagellum of trichomonas 

 is attached to the border of the undulating membrane, and in both 

 flagellates this attachment may be broken down and the flagellum 

 become free except at its point of origin. Tricercomonas, as the 

 figures show, has three long anterior flagella and one posterior 

 flagellum passing over the flattened side of the body, which more- 

 over is sometimes grooved along its course. The flagellate resembles 



* See inset betiveen pages 148 and 149. 



