THE MASTIGOPHORA 



273 



in the Protomonadina, and then to divide the order into two suborders ; the 

 tirst, entitled the Monozoa, would include the Protomonadina as constituted 

 above, with the exception of the Trypanosomidce (" Binucleata "), and with 

 the addition of the Tetramitidce. The second suborder, Diplozoa, would in- 

 clude only the Octomiiidce. This arrangement certainly seems more natural 

 than that which is usually adopted, so far as the Tetramitidce and Octomitidce 

 are concerned. 



ORDER IV. : EUGLENOIDINA. Larger forms, with mouth-aperture and 

 oesophagus ; with a complex vacuole- system opening into the oesophagus ; 

 often with holophytic apparatus, chromatophores, stigma, etc. 



This order represents, so far as structural complication of the individual 

 is concerned, the highest type of organization among Flagellata. The body 

 may be metabolic, or of definite contours, with thick cuticle. The free-living 



FIG. 117. Lamblia intestinalis. A, Ventral view ; B, side view. N., One of the 

 two nuclei ; ax., axostyles ; ft. 1 , fl. 2 , fl. 3 , fl.*, the four pairs of flagella ; s., sucker- 

 like depressed area on the ventral surface ; x, bodies of unknown function. 

 After Wenyon (277). 



forms are either holozoic or saprophytic, if colourless, or holophytic if pro- 

 vided with chromatophores, in which case they may be capable of nourishing 

 themselves by more than one method. The flagellum may be single, or there 

 may be a second flagellum, usually smaller than the principal flagellum, 

 and sometimes directed backwards as a trailing flagellum. The attachment 

 of the flagellum is of the second type (p. 263), with blepharoplast distinct 

 from the centrosome. According to Hartmann and Chagas (62), in Peranema 

 trichophorum the centrosome first divides to furnish a blepharoplast, and 

 the latter, having become completely independent of the nucleus, divides 

 into two, a distal blepharoplast or basal granule of the flagellum, connected 

 by a rhizoplast (centrodesmose) with the proximal blepharoplast or anchoring 

 granule. The authors consider that this should be regarded as a fourth type 



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