GENUS: RHYNCHOMONAS 611 



coprozoic flagellate from the intestinal contents of cockroaches. Belaf, 

 who obtained a culture of Rhynchomonas nasuta, has studied its structure 

 and method of division (Fig. 251). The organism is ovoid in shape, and 

 resembles members of the genus Bodo in the possession of a nucleus and 

 kinetoplast. From the latter there arise two axonemes, one of which 

 becomes a flagellum in the notch formed by the digital process, while 

 the other is continued to the end of the process, but does not become a 

 flagellum. The single flagellum acts as a trailing flagellum. The flagellate 

 is evidently closely allied to species of Bodo, and the notch behind the 

 digital process bears a striking resemblance to the cytostome of the 

 flagellates of this genus. Not infrequently in such a form as B. caudatus 

 the portion of the body in front of the cytostome has the appearance of a 

 digital process, so that it does not seem improbable that the notch formed 

 by the digital process may be actually a cytostome. 



4. Family: prowazekellid^ Doflein, 1916. 

 This family includes the single genus Prowazekella, established by 

 Alexeieif (1912), the members of which are parasitic in the intestine of 

 lizards. The encysted forms are remarkable in that great increase in 

 size takes place after the cyst wall has been formed. 



Prowazekella lacertae (Grassi, 1879). — Grassi(1879rt), who first saw this flagel- 

 late, iuchided it in liis genus, Monocercomonas. He afterwards (1881a) placed it in 

 Dujardin's genus, Heteromita, while Prowazek (1904fl) referred it to the genus Bodo. 

 Alexeieff (1911) described another form from the intestine of newts, salamanders, 

 and axolotls, and included the two forms in the genus Heteromita. In the following 

 year (19126) he created the new genus, Prowazelcella, for these flagellates. 



P. lacertcB occurs in the intestine of lizards {Lacerta, Tarentola, etc.). 

 The fully-grown flagellate has an elongate pyriform body, 10 to 30 microns 

 in length (Fig. 252). It has a tapering posterior end and blunter anterior 

 end, from which arise two flagella. One of these is directed forwards, and 

 may be four times the length of the body, while the other is a trailing 

 flagellum about twice the length of the body. The latter, in its backward 

 course, is sometimes attached to the surface of the body for a short 

 distance before becoming free. There is a nucleus near the anterior end, 

 consisting of nuclear membrane and a central karyosome. Surrounding 

 the nucleus are one or more bodies, the parabasals, while extending from 

 the anterior end of the nuclear membrane is an axoneme (rhizoplast), 

 which is continued into the two flagella. The life-cycle of the flagellate 

 was described by Chatton (19176) in the case of the form which occurs in 

 the gecko, Taretitola fnauritanica. The flagellate multiplies by longitudinal 

 division in the gut of the lizard. Certain forms then lose their flagella, 

 and, becoming ovoid in shape, produce cysts which have a diameter of 



