MASTIGOPHORA 487 



Class II. Mastigophora 



These are protozoa in which one or more permanent organs 

 serving for locomotion or food capture are present in the form of 

 flagella. As a rule the body is limited by either a cuticle or a 

 differentiation of the protoplasm into a firmer external portion or 

 periplast. One, two, or more flagella may be present, and when 

 multiple are arranged in various ways. Food-vacuoles may occur 

 in the protoplasm, also contractile vacuoles, but not in the parasitic 

 forms. Various other granules, including chromatophores, which 

 generally contain chlorophyl, may be present. The nuclear appa- 

 ratus is usually double, consisting of a large principal or macro - 

 nucleus, and a small or micronucleus or blepharoplast ; the latter 

 is not, as in the Infusoria, composed of generative chromatin, and 

 is in relation with the locomotor apparatus. An undulating mem- 

 brane, a thin protoplasmic membrane attached to one aspect of 

 the body like a dorsal fin, may be present. Euglena is a common 

 form in ditches, and Noctiluca is the chief cause of phosphorescence 

 in the sea ; both are uniflagellate. Volvox and Protococcus are 

 also placed by some in this group. The chief parasitic genera 

 are : 



Trypanosoma and Trypanoplasma, both of which have an undu- 

 lating membrane, but the former has one flagellum, the latter two 

 flagella, one at each end of the body, but both starting from the 

 blepharoplast. Spirochaeta (see p. 493). 



Herpetomonas, like Trypanosoma, has a single flagellum, but no 

 undulating membrane. 



Crithidia has a pear-shaped body with single flagellum. 



Trichomonas, also somewhat pear-shaped, with three short 

 flagella and an undulating membrane. 



The trypanosomes and other forms living in the blood are known 

 as haemoflagellates. 



Trypanosomata * 



The trypanosomes are all parasitic in the blood of vertebrates, 

 and a blood-sucking invertebrate is almost invariably concerned 

 in their transmission. In the case of each pathogenic trypanosome, 

 some indigenous wild animal, tolerant to that form, serves as a 

 reservoir from which infection is derived. 



1 For current literature on Trypanosomes and trypanosome diseases 

 see The Tropical Diseases Bulletin. 



