DERIVED ORGANIZATION 129 



with the silver line system. In connection with Dijplodinium 

 ecaudatum, Sharp described, for the first time in the literature, a 

 system of connected fibrils emanating from a common mass of 

 differentiated protoplasm, which he called a "motorium," the whole 

 system being termed the 'neuromotor apparatus." The motorium 

 is situated in the ectoplasm of the anterior end of the organism 

 between the two zones (adoral and dorsal) of membranelles (Fig. 2, M, 

 p. 20.) From it as a center a number of fibers pass to different regions 

 of contractile activity. These fibers are named and interpreted by 

 Sharp as: (1) A circiimesophageal ring strand running to a definite 

 ring of substance similar to that of the motorium encircling the gullet 

 (esophageal ring), from which other fibers apparently take their 

 origin and run posteriorly along the retractile gullet; (2) a dorsal 

 motor strand running to the bases of the adoral membranelles; (3) 

 opercular fibers or a group of fibers running to the operculum 

 (see Fig. 2). 



The delicacy of structure and the position of this amazingly com- 

 plex aggregate are sufficient evidence to disprove any hypothesis of 

 a supporting function. Self-perpetuation of the elements by division 

 indicates no relationship to supporting structures such as trichites 

 (oral basket) in the mouth regions of forms belonging to the family 

 Chlamydodontidae. Their position in the cell and the attachments 

 of the several fibrils are arguments against their interpretation as 

 myonemes. 



McDonald (1922) has recently described a somewhat similar 

 neuromotor system in Balantidium coli and B. mis. Here an ante- 

 rior motorium gives rise to (1) a ring-form fibril which passes around 

 the adoral cilia region and (2) a similar ring fibril passing around 

 the gullet. Other elements of the system consist of basal granules 

 of the cilia, from which rhizoplasts pass inward to the central region 

 of the cell. At the point where each rhizoplast enters the endoplasm 

 is a granular thickening from which a radial fibril passes toward 

 the periphery where it ends blindly. 



Many other ciliates have been added to this list of motorium- 

 bearing forms, but we are still ignorant as to the origin and history 

 of the motorium during division. Amongst these forms are: Para- 

 mecium (Rees), Glaucoma frontata (Calkins and Bowling, 1929), 

 Uroleptus halseyi (Calkins, 1930), Concho phthiri us mytili (Kidder, 

 1933), and others. Until we have some positive evidence of its origin 

 and perpetuation by division, the interpretation of the motorium as a 

 definite organoid of the cell must be held in reserve (cf. Ilees, 1931; 

 Turner, 1933). 



Evidence in favor of a conductile function of such a neuromotor 



system is furnished by the observations of Yocom (1918) and the 



micro-dissection experiments of Taylor (1920) on Ewplotes patella. 



In Euplotidae, apart from the motile organs, contractility is un- 



9 



