TRICHOMONAD FLAGELLATES. 307 



the parabasal or homologue is often more condensed (not, howe^'er, 

 in the trypanosonies) and hes nearer the blepharoplast and nucleus as 

 in Parajoenia. 



A. discussion of the grounds for including the kinetonucleus of 

 trypanosonies in this series will appear in a later paper by the junior 

 author. Should this homology here suggested be accepted as estab- 

 lished by later investigations it may be desirable to apply the term 

 parabasal to the whole series of homologous structures, reserving 

 the special names for purposes of differentiation among them. 



The function of this chromatic basal rod, or parabasal, is indicated, 

 as Janicki (1911) has suggested, by its relationship to the incessantly 

 active undulating membrane throughout its whole length. Its micro- 

 chemical reaction, at least to a number of stains, is the same as 

 that of the blepharoplast from which it and the motor organelles take 

 their origin. It has, therefore, some relation to the motor activity of 

 the undulating membrane and probably one similar to that which the 

 blepharoplast bears to the activity of the flagella. It is stock of 

 deeply staining chromatic substance attached immediately at the 

 base of the region of maximum motor activity in the organism, and 

 is connected with blepharoplast and nucleus where such substance, 

 or allied substances, are formed. Its function is not primarily skeletal 

 or supporting, but rather connected with the metabolism, of, and 

 possibly also with the control of the motor activity. Analogy to the 

 neuromotor apparatus of Diplodinium as described by Sharp (1914) 

 is suggested by the structural relations. 



The parabasal body in Trichomonas and Tetratrichomonas is a 

 relatively long slender body below the undulating membrane. How- 

 ever, in the nearly related Trichonymphida, in which no undulating 

 membrane occurs, the parabasal is condensed in a stout p^Tiform 

 organelle which together with the rest of the extranuclear motor 

 apparatus is developed in connection with each of the many nuclei as 

 for example in Stephanonympha. Here also at mitosis the new 

 organelle is formed by outgrowth from the blepharoplast and is 

 attached to one daughter blepharoplast while the old parabasal is 

 attached to the other. In this connection it should be noted that 

 Dcvcscovina driata Foa, a heteroinastigote flagellate with three an- 

 terior and one trailing flagellum and a large parabasal wound spirally 

 around the axostyle (see Janicki, 1911, Fig. 1) properly belongs in the 

 Polymastigina near Eutrichomastix. 



The axostyle (ax. Fig. B.) is a stout hyaline, club-shaped structure 

 lying in the axis of the body. Its anterior end, for about 0.2-0.3 of 



