1920] Taylor: Neuromotor Apparatus in Euplotes 439 



crawls a short distance over debris. Does not show creeping "avoiding 

 reaction" when stimulated with needle-point or by means of methylene blue. 

 Also, applied weak acetic acid, when part swam straight forward, then reversed 

 the effective stroke of organelles, swimming backwards a short distance, but 

 again swam in circuit or in spiral apparently bej'ond the influence -of the acid 

 solution. 



Posterior part turned over and over very rapidly, two times per second, with 

 cut surface as axis. This continued about twelve minutes. Slowed and came 

 to rest on surface film of hanging drop. Half hour later, very irresponsive to 

 jarring or needle-point. Aroused and for few seconds revolved as before, but 

 very slowly and chiefly by means of the marginal cirri. Anal cirri mostly 

 passive or individually and irregularly active. Again came to rest. From 

 jarring, slowly moved in circuit, very awkwardly, by irregular pushing of one 

 or two anal cirri; other anal cirri were passive. 



Excisions 



Removal of oral lip with adoral membranelles. — Anterior piece 

 always shows one and only one reaction, viz., circus movement to the 

 right. This movement is very rapid and continues until the part 

 becomes fatigued and dies, which generally occurs within fifteen min- 

 utes or less after the excision. The effective stroke of the mem- 

 branelles is the same here as when the normal animal swims in a circuit 

 or spirally straight ahead. In many specimens observed, there was at 

 no time any indication of the reversal of membranelles, and the path 

 of the circuit was continuously about the same. This part did not 

 possess the motorium. 



The reactions of the posterior part are mostly very similar to those 

 described for the same part when a transection was made between the 

 "group of three" and "group of four" frontal cirri. In the former, 

 however there are present the "group of three" frontal cirri and the 

 motorium. This piece is able to creep fairly normally and in a few 

 instances gave the creeping "avoiding reaction," although the anterior 

 end here w-as much less sensitive than the oral lip of a normal form. 

 Swimming is uncommon and abnormal. Spiral rotations on the long 

 axis are infrequent and quite imperfect. The part more frequently 

 revolves with the cut surface as an axis, but this movement is generally 

 combined with a sort of spiral movement on the long axis. Of five 

 such posterior parts carefully observed, one regenerated an oral lip 

 after budding off about twenty microns of its anterior end; the bud, 

 containing three frontal cirri, was more or less spherical, quite active 

 for about an hour, but died some time during the night. The other 

 four of these five regenerated normally but only after eighteen to 

 thirty hours. 



