634 FAMILY: CERCOMONADIDyE 



C. Cercomonadidae with Three Anterior Flagella. 



Genus: Tricercomonas Wenyon and O'Connor, 1917. 



This genus was founded by the writer and O'Connor (1917) for a flagel- 

 late having the general structure of a member of the genus Cercomonas, 

 except that it possessed three anterior flagella instead of one. There is 

 only one species. 



Tricercomonas intestinalis Wenyon and O'Connor, 1917. — This is a 

 minute pear-shaped organism which has three anterior flagella and a 

 fourth posterior one, the axoneme of which is attached to the surface of 

 the body. The name T. intestinalis was given to this flagellate by the 

 writer and O'Connor, who discovered it in diarrhoeic stools in Egypt. 

 The writer saw the same organism later in several cases in Macedonia, 

 while it was recorded by Kofoid, Kornhauser, and Plate (1919) and Kofoid 

 (1920) in soldiers who had returned to New York from service abroad. 

 Lynch (1922a) and Boeck (1924) have seen it in North America, Jepps 

 (1923) in Malaya, and Da Cunha and Pacheco (1923) in Brazil. 



The flagellate, which is an active metabolic organism when seen in 

 freshly passed stool, is 4 to 8 microns in length (Fig. 261). It is pear- 

 shaped, but the side along which the axoneme of the posterior flagellum 

 passes is somewhat flattened. The posterior extremity is often drawn out 

 into a tail, while the flagellum is continued for a short distance beyond the 

 end of the tail. In stained specimens a nucleus can be seen near the 

 anterior end of the body. It has a central karyosome, while the nuclear 

 membrane is drawn out into a cone, from the apex of which the axonemes 

 of the flagella originate. 



Reproduction takes place by longitudinal division, but only isolated 

 stages of this process were seen. The accounts of the flagellate given by 

 Lynch (1922a) and Boeck (1924) agree in the main with that of the writer 

 and O'Connor (1917). The organisms described by Brug (1923) and 

 Jepps (1923) as Enteromonas hominis are unquestionably T. intestinalis. 

 Boeck (1924), who has cultivated the organism in his L.E.S. medium 

 from a human case, gives the measurements of the flagellate as 4 to 10 

 by 3 to 6 microns. The nucleus is described as spherical, and two ble- 

 pharoplasts were noted near the nuclear membrane. In one of these the 

 axonemes of the three anterior flagella originated, while the other gave 

 origin to the axoneme of the posterior flagellum. Boeck believes that 

 the cone-like appearance of the nucleus described by the writer and 

 O'Connor is not a normal one. A similar cone-like arrangement occurs, 

 however, in Cercomonas longicauda and Heteromita uncinata. In one of 

 the cases studied by the writer and O'Connor, encysted forms of T. intes- 

 tinalis were encountered. Cysts were also seen by Boeck. These are 



