48 University of California Puhlications in Zoology [Vol. 20 



and strictlj' motor functions can not be sharply drawn and that the 

 two functions are in all probability not wholly separated and carried 

 on by distinct organs, but are rather in most, if not all parts of the 

 system, served to some extent by the same structures. It is possible 

 that the basal ciliary lines (6. cil., fig. B) are wholly conductile rather 

 than motor, and that the centroblepharoplast has little if any motor 

 function. It is likewise not improbable that the longitudinal and 

 transverse myonemes are mainly motor and that the flagella and cilia 

 are sensory, conductile, and motor, while the enveloping undiffer- 

 entiated cj'toplasm in which all these structures lie, except cilia and 

 flagella, has doubtless preserved some of its primitive neuromotor 

 capacities. The oblique fibers are by their staining reaction allied 

 to the neural system and function rather than to the motor. These 

 overlapping conditions, however, do not preclude the use of the tenn 

 neuromotor system to designate the complex integrated fibrillar 

 structure of Trichonymplw. 



The discussion of this system will for convenience include also that 

 of the surrounding cj^toplasmic structures, such as the surface ridges, 

 and the alveolar layer, although these are not strictly parts of the 

 system. 



The neuromotor sj-stem (fig. B) may be divided into two very 

 unequal parts according to its location in the two fundamental sub- 

 divisions of the cytoplasm, the ectoplasmic and endoplasmic. The 

 ectoplasmie portion consists of the anteriorly located centroble- 

 pharoplast (centrobleph.) from which spring the anterior flagella 

 {ant. fl..) and from which radiate posteriorly the longitudinal basal 

 ciliary lines (&. cil.) which give rise laterally to the lateral cilia 

 {lat. cil.) and posteriorly to the posterior cilia {post. cil.). These 

 lines are in the axes of the longitudinal ridges {surf, rdg.) which cover 

 the surface above the equator of the posterior region. From the 

 centroblepharoplast arise also the spirally directed, opposing sets of 

 oblique fibers {ohl. /.). 



One set of fibers, the circular transvei-se mj-onemes {tr. my.), lies 

 in the innermast zone of the ectoplasm, or outermost zone of endo- 

 plasm. Their course is such that their connection, if any exists, with 

 the centroblepharoplast can not be traced. In the peripheral laj-er 

 of endoplasm the stout longitudinal myonemes run posteriorly from 

 the centroblepharoplast to the margin of the thick ectoplasmic zone. 

 No trace of any other part of the neuromotor apparatus can be found 

 within the labile endoplasm. The juxtaposition of nucleus and cen- 



