GENERA RHIZOMASTIX AND PROLEPTOMONAS 297 



Rhizomastix gracilis AlexeiefE, 1911.^Tliis flagellate (Fig. 140), wMch 

 varies in length from 6 to 11 microns, has been described from the intestine 

 of axolotls by Alexeief? (1911), and by Mackinnon (1913) from tipulid 

 larvse. It has the structure described above, and produces spherical 

 cysts, within which nuclear division occurs. 



YakimofE and Kolpakoff (1921) described as Pararhizomastix hominis a 

 flagellate isolated by them from human faeces planted on agar media. 

 The organism closely resembles Alexeief?'s Rhizomastix agilis of the 

 axolotl. The authors do not 

 state the grounds on which 

 they create the new genus, 

 nor why they regard the 

 flagellate as a human parasite, 

 and not a coprozoic organism, 

 which it undoubtedly is. 



Genus: Proleptomonas Woodcock, 1916. 



This genus was founded by Woodcock 

 (1916) for a flagellate which he discovered in 

 cultures from faeces of goats (Fig. 141). On 

 account of its resemblance to the leptomonas 

 of insects, it was placed by him in a new 

 genus, P)'oleptomonas, of which there is one 

 species. 



Proleptomonas fsecicola Woodcock, 1916. — 

 This flagellate measures from 7 to 8 5 microns 

 in length by 1-25 to 1-75 microns in breadth 

 (Fig. 141). There is a long anterior flagellum 

 16 to 21 microns in length and a central 

 nucleus, in front of which is a blepharo- 

 plast from which arises the axoneme of the 

 flagellum. Woodcock thinks it possible that P. fcecicola may be the 

 present-day representative of the ancestral type from which the para- 

 sitic flagellates of the genus Leptomonas were derived. Fantham (1922) 

 has seen a similar flagellate in decomposing cabbage, and, owing to 

 the fact that a definite kinetoplast was present, he regards it as differing 

 from Woodcock's Proleptomonas. He gives it the name Herpetomonas 

 hrassicce. Another form found in soil he names H. terricolce. These 

 flagellates, however, do not belong to the genus Herpetomonas, and 

 it is not improbable that they are identical with Proleptomonas fcecicola. 



Fig. 141. — Proleptomonas 

 fcecicola : A Coprozoic 

 Flagellate from F.eces 

 of Goats ( x 3,000). 

 (After Woodcock, 1916.) 



