MORPHOLOGY AND TAXONOMY OF MASTIGOPHORA 295 



Fyrsonympha and Dincnympha (Monozoa) the axostyle may vibrate 

 actively in the endoplasm of the cell. In the majority of forms, 

 however, the axostyle is fairly rigid, projecting in some genera 

 beyond the posterior cell periphery {Trichomonas, Foaina, etc.). 



Most of the Polymastigida are parasitic and colony formation is 

 unknown. In many genera one at, least of the flagella is trailing 

 or united with the periplast to form an undulating membrane. 

 The kinetic elements are complex and present in some way or other 

 all known derivatives of the blepharoplast, including basal bodies, 

 blepharoplast, parabasal body, centrioles and rhizoplasts. Chromo- 

 somes of definite form and number are characteristic and a central 

 spindle which in most flagellates is intranuclear (centrodesmose) is 

 here, in the majority of forms at least, outside the nuclear membrane 

 (paradesmose) . 



The periplast is usually delicate permitting metaboly or plastic 

 changes of the body form. Contractile vacuoles are absent. A 

 mouth opening is common and may be accompanied by a definite 

 pharynx. Nutrition is usually holozoic but some forms are sapro- 

 zoic. Reproduction is t^TDically by longitudinal di^■isi()n but 

 multiple division with somatella formation is widely distributed. 

 Encystment is practically universal and infection of new hosts is 

 brought about by such c>'sts through contaminative infection. 

 Sexual processes have been described but the data are uncon^•incing 

 and the interpretation very questional)le. Bimting (1922) describes 

 a species of Tetramitiis as the flagellated phase of a coprozoic 

 Amoeba. 



Polymastigida are characteristic parasites of the digestive tract 

 and may usually be found in the intestine of any vertebrate par- 

 ticularly mammals and man, or in the intestine and rectum of 

 many kinds of invertebrates particularly of insects. Their patho- 

 genic effects on the host are questionable but in no case are they 

 as severe as those due to the Protomastigida. Octonutus salmonis 

 (Moore, 1922) however, like LeishiiKuiia and Trypanosoma has an 

 intracellular developmental phase whereby multitudes of cells of 

 young trout are destroyed and the trout killed (Davis, 1923). 



Order IV. HYPERMASTIGIDA, Grassi. 



The organisms included in this Order are parasites of insects, 

 particularly of Termites and are the most highly specialized of the 

 IVIastigophora. Many authors indeed, make them a distinct class of 

 the Protozoa. Flagella are numerous and may arise from all parts 

 of the body but they are always connected by coordinating fibrils 

 or rhizoplasts, with a centroblepharoplast at the anterior end. 



The peculiar s\mbiotic relations of Termites and these H^1^er- 

 mastigida have been cleared up by the excellent work of Cleveland 



