FLAGELLATA I I 5 



An uiidulatiug membrane occurs, sometimes passing into tlie 

 tiagelluin in certain genera, all parasitic, such as Trypanosoma 

 (incl. Herpetomonas), Trichomonas, Hexamitus, and Dineni/mpha. 



In some cases the flagellum (or flagella) is inserted into a 

 detinite pit, which in allied forms is the mouth-opening. The 

 contractile vacuole is present in tire fresh-water forms, but not 

 in all the marine ones, nor in the endoparasites. It may be 

 single or surrounded by a ring of minute "formative" vacuoles 

 or discliurge into a permanently visible " reservoir." This again 

 may discliarge directly to the surface or tlirough the pit or canal 

 in which the flagellum takes origin (^Euglena). 



The " chromatophore " may be a single or double plate, ov 

 multiple.^ In tlie peculiar form Paramoeba the chromatophore may 

 degenerate and be reproduced anew. It often encloses rounded or 

 polygonal granules of uncoloured plasma, very refractive, known 

 as " pyrenoids." These, like the chromatophores, multiply by direct 

 fission. The "reserves" maybe (1) fat-globules; (2) granules of 

 a possibly proteid substance termed " leucosin"; (3) a carbohydrate 

 termed " paramylum," differing slightly from starch (see p. 95): 

 (4) true starch, which is usually deposited in minute granules to 

 form an investment for the pyrenoid wlien such is present. 



A strongly staining granule is usually present in the plasma 

 near the base of the flagellum. This we may term a " blepharo- 

 pList " or a " centrosome " in the wider sense. 



Fission is usually longitudinal in the active state ; a 

 few exceptions are recorded. Encystment is not uncommon ; 

 and in the coloured forms the cyst - wall is of cellulose. 

 Division in tlie cyst is usually multiple ; " in the coloured 

 forms, however, vegetative growth often alternates with 

 division, giving rise to plant-like bodies. Polytoma and oLlier 

 Chlamydomonadidae multiply by " brood-formation " in the 

 active state ; the blepharoplast, as Dangeard suggests, persist- 

 ing to continue the motion of the flagella of the parent, while 

 the rest of the plasm divides to form the brood. Conjug-ation 

 has been observed in many species. In some species of 

 Chlamydomonas it takes place after one or both of the two 



^ Tlie colouring matter is chlorophyll or some allied colouring matter. In (ho 

 jellow and brown forms the additional pigment is termed loo.sely "diatomin." 

 but its identity with that of Diatoms is in no case proved. 



^ Notably in the Craspedomonadidae, where transverse division also occurs. See 

 Raoul France, Z>ic Craspcdomonadineen (Buda-Pesth, 1897). 



