XIII, D, 5 Haughivout: Protozoa of Manila and Vicinity: I 201 



Subphylum MASTIGOPHORA— Continued. 

 Class Zobmastigophora — Continued. 

 Subclass Lissoflagellata — Continued. 

 Order Heteromastigida — Continued. 



directed forward and the other or others directed downward 

 and backward — the so-called heteromastigote types. The for- 

 ward flagellum is used in locomotion. The bodies are naked 

 and plastic or provided with a highly differentiated membrane. 

 Order Trypanosomatida. — Exclusively parasitic forms of vertebrates 

 and some invertebrates. Those found in the blood of mammals 

 may have a stage in the life cycle occurring in some arthropod, 

 or an arthropod may be the direct or mechanical transmitter.^^ 

 Trypanosomes of fishes in many instances are transmitted by 

 leeches. These organisms are elongated, usually pointed at 

 each end, and have one or two flagella arising from the kineto- 

 or motor nucleus. There is an undulating membrane, bordered 

 by a flagellum, running from the kinetonucleus at the posterior 

 end to the anterior end, where the flagellum is usually continued 

 as a free lash. This undulating membrane is believed to be 

 supplied with myoneme fibrils. In addition, there is a tropho- 

 nucleus, which regulates the vegetative functions of the cell. A 

 large group, of which the complete life history is known in no 

 case. Typical genera: Trypanosoma Gruby, 1841; Trypanoplas- 

 ma Laveran and Mesnil, 1904. 

 Order Polymastigida. — This order is characterized by species having 

 numerous flagella, which may be arranged in groups. There 

 may be one or many mouth openings, which are usually situated 

 at the bases of the flagella. Some forms possess undulating 

 membranes of a type similar to that seen in Trypanosoma. 

 Tnese may be bordered internally by a parabasal body. The 

 order includes many parasitic species. 

 Tribe 1. Astomea. — The flagella are numerous and uniformly dis- 

 tributed. There are no special mouth openings. Typical 

 genus, MulticiJw, Cienkowsky, 1881. 

 Tribe 2. Monostomea. — ^The mouth opens at the base of a group 

 of from three to six flagella. Typical genus, Trichomonas 

 Donne, 1837. 

 Tribe 3. Distomea. — There are two groups of flagella with a mouth 

 opening at the base of each. Typical genus, Hexam,itus Du- 

 jardin, 1838. 

 Tribe 4. Trichonymphlnea. — Parasitic forms found in the digestive 

 tracts of termites. They are covered with a coating of long 

 flagella. There is a stout pyriform organelle, developed ap- 

 parently in connection with the nucleus, which bears a simi- 

 larity to the parabasal body of Trichomonas. Typical genus, 

 Trichonympha Leidy, 1877. 

 Order Euglenida. — Large, free-living forms having one or two flagella. 

 The body is contractile, showing the metabolic or euglenoid 

 movements, with often a complicated body wall. There is a 

 mouth and pharyngeal opening at the base of the flagella, which 



" It is to be doubted if true trypanosomes ever occur as parasites of 

 non-blood-sucking arthropods. 



