156 ZOOLOGY 



motorium, a circumoesophageal ring which appears to be another 

 constant feature of the apparatus. This ring has fibres directed 

 posteriorly to the wall of the gullet (Campbell (18) ). Sharp also 

 finds fibres to the dorsal membranelles and to the adoral mem- 

 branelles. The operculum of Diplodinium also has special fibres. 

 It was the structural relations of the various parts of this sytem 

 with the motor organs that led Sharp to the conclusion that 

 together they formed a neuro-motor apparatus. 



Taylor found in Euplotes an admirable material for experi- 

 mental investigation. Owing to the rigid pellicle surrounding the 

 animal he was able to make incisions in the cell without causing a 

 physical collapse. The neuro-fibres were further identifiable in 

 the living organism both with and without the use of vital 

 dyes. Having made a very complete study of the normal locomo- 

 tion of this Ciliate, he was in a position to examine the effects of 

 section of the neuro fibres with confidence. From his experi- 

 ments there is no doubt that these fibres do act as a co-ordinating 

 mechanism. Thus cutting the anal cirri fibres affects the creeping 

 and swimming movements dependent upon the action of these 

 cirri ; destruction of the motorium and cutting the attached 

 fibres interrupts the co-ordination of the movements of the loco- 

 motor organs, the membranelles and the cirri. 



The conductive part of the system appears to consist, in those 

 forms, so far studied of (1) the motorium, (2) the circumoesophageal 

 ring, (3) dorsal and ventral fibres running to the ectoplasm 

 beneath the cilia ; the dorsal (or anterior) fibres appear to be the 

 commoner and most strongly developed running to the peristomial 

 region (Campbell (18) ), (4) the adoral fibre which runs around the 

 pharynx in a spiral and connects up with all the pharyngeal mem- 

 branelles (Fig. 67). There are two of these in Boveria teredinidi, 

 which has a very complicated system. 



The only form differing widely from these is Parmncecium, 

 which is a generalised form without any very special locomotor 

 organs (115). It has a generalised neuro-fibrillar system consist- 

 ing of a neuromotor centre (demonstrated with difficulty, but 

 evidently corresponding to the motorium), from which radiate 

 out two sets of fibres. Firstly two peripheral whorls, the larger 



