406 University of California Publications in Zoology [VOL. 19 



in certain trichomonads. Of this genus, Trichomonas augusta (Kofoid 

 and Swezy, 1915) possesses a motor mechanism to whose blepharoplast 

 are attached: (1) three equal anterior flagella, (2) one intracyto- 

 plasmic flagellum, the axostyle, (3) a trailing flagellum attached 

 laterally along the margin of the undulating membrane, and (4) an 

 elongated, chromatoidal rod, the parabasal body, which lies along the 

 proximal edge of the undulating membrane. Recalling the occurrence 

 of a trailing flagellum and the elongated parabasal body in Trypano- 

 plasma congri, an homology between these and structures (3) and (4) 

 in Trichomonas augnsta appears obvious. 



But the complexity of the motor apparatus does not end with the 

 trichomonads. In the other genus of the Polymastigina, the Octo- 

 mitidae, appear further advances in the series. An amphibian para- 

 site, Octomitus dujardini (Dobell. 1909) claims for its motor mech- 

 anism a pair each of blepharoplasts, parabasal bodies and axostyles, 

 and three anterior flagella attached to each blepharoplast. Omitting 

 the undulating membranes, Octomitus is really the equivalent of two 

 trichomonads. This duplex condition does, in fact, become complete 

 in Giardia (Kofoid and Christiansen, 19156, Boeck, 1917), the remark- 

 able motor mechanism of which rivals in complexity that about to be 

 described for certain ciliates. There is a duplication here of each 

 structure found in the apparatus of Trichomonas. But with the con- 

 nection of the two blepharoplasts by a commissure and with a chiasmal 

 crossing of the anterior lateral flagella, two organisms become inte- 

 grated into one individual (Kofoid and Christiansen, 19156). 



It was suggested by Professor Kofoid (Kofoid and Christiansen, 

 19156) that this integrating fibrillar complex in Giardia, associated 

 with the blepharoplasts, parabasal bodies and the very active organelles 

 of locomotion, was neuromotor in function. To the system he assigned 

 the name "neuromotor apparatus" which has since been applied to 

 homologous fibrillar systems in other flagellates of the above series. 



The series indicated in the foregoing examples has been consider- 

 ably amplified by a number of other flagellates (Swezy, 1916) which 

 show greater or less complexity in their motor apparatus. For the 

 ciliates, however, no such assemblage has yet been made, although this 

 large field would seem only to await further investigation. Numerous 

 forms of this class have long been known to possess intracytoplasmic 

 structures associated with their motor organelles, but the morphological 

 relationship of these structures has been completely worked out in 

 only two organisms. 



