Tii'tliir: If euromotor Apparatus in /.'/*/<//< \ \:\.\ 



the anal cirri fibers had been severed. It is important and significant 

 in this connection to recall that the severing of the anal cirri fibers 

 did not incapacitate any of the four movements of the anal cirri. 

 Kadi of these movenieiits lias been clearly observed ill the anal cirri 

 upon supporting such an incised animal, ventral side down, by means 

 of a very flexible needle against the under surface of the cover-glass. 

 Occasional, usual creeping or swimming inovements by the incised 

 animal might, therefore, be expected as occurring incidentally. 

 A'-'-onlingly, it is the infrequency of these occurrences and not their 

 absence that suggests the want of coordination and warrants the con- 

 clusion that the fibers are conductive in function. 



Perfect and efficient coordination between the series of mcm- 

 branelles and the five anal cirri is accomplished through the normal 

 functioning of the motorium and its attached fibers. Whether the 

 fibers were cut on both sides of the motorium or the motorium dest roved 

 by means of the needle-point, the effects were very much the same. 

 The usual swimming movements were more distinctly altered than 

 were the creeping movements. Changes from normal conditions were 

 the rarity of creeping movements, their slow rate, very infrequent 

 avoiding reactions and the tendency of the animal when not swim- 

 ming to remain quite passive on debris and unusually irresponsive to 

 mechanical stimuli. The most common reactions in swimming were 

 the right circus inovements. which, here, were more often combined 

 with abnormal, spiral revolutions in which the anterior described much 

 wider spirals than did the posterior end. In no case was the backward 

 swimming reaction observed, although, as described above, the reversal 

 of both the adoral membranelles and the anal cirri was clearly seen. 

 It will be recalled that when the anal cirri fibers were cut very con- 

 spicuous effects were seen in the want of concomitaney and coordina- 

 tion between the movements of the membranelles and of the anal cirri. 

 This, perhaps, showed more clearly than any other experimental 

 evidences that this fibrillar complex is coordinative in function. 



1'ert'ect and efficient coordination between the series of mem- 

 branelles and anal cirri is contingent essentially and only upon the 

 motorium with its attached fibrillar complex. Any incisions through 

 any region of the body, which did not sever or injure this fibrillar 

 apparatus neither impaired the perfect coordination of the mem- 

 branelles and anal cirri, nor modified the animal's normal creeping 

 and swimming movements. Whether these incisions did or did not 

 pass through the macronucleus, the results were always without 



