1920] Taylor: Neuromotor Apparatus in Euplotes 441 



body. In several cases the anal cirri, to about two-thirds of their 

 length, the marginal cirri and a small piece of the caudal end of the 

 body were excised. Creeping was thus made practically impossible, 

 the animals resorted more frequently to circus movements to the right, 

 and sharp turns to the right were not evident. Spiral revolution on 

 the long axis was apparently normal. Four such animals regenerated 

 the excised parts, including the anal cirri. 



Several attempts were made to gouge off the anal cirri just as the 

 frontal cirri had been removed. In two experiments (nos. 215 and 

 216) all the anal cirri were successfully removed, with little or no 

 injury to the body. In each rase, then' followed several significant 

 results : (1) the animal was unable to creep, (2) it did not turn sharply 

 to the right, (3) the avoiding reaction was never observed, and (4) 

 circus movements to the right were performed more frequently. 



Experiment 216. — Removed anal cirri 4 and 5 (see p. 424). Released tlie 

 animal by adding water to the hanging drop. It then performed all the major 

 swimming and creeping movements, including the avoiding reaction. 



Again drew off the water and removed the remaining anal cirri. Upon adding 

 more water the animal was observed to revolve in spirals on the long axis and 

 to swim in circuits to the right, but at no time was it seen either to creep, to 

 turn sharply to the right, or to give the avoiding reaction. Its efforts to creep 

 on the under side of the cover-glass were unsuccessful, the posterior end being 

 suspended so as to incline the body at an angle of about 30 degrees with the 

 cover-slip. 



Incisions 



Through the oral lip without cutting the cytostomal fiber. — There 

 was no apparent decrease in the sensitivity of any part of the oral lip, 

 and no change in the normal movements and functioning of the adoral 

 membranelles. The results were wholly negative. The cut usually 

 healed completely within an hour. 



Through the oral lip, severing the cytostomal fiber (fig. 5). — Iu 

 seventeen cases there resulted abnormal swimming movements and 

 distinct changes in the movements of the membranelles on either side 

 of the incision: fl) the progress of the animal forward was impeded, 

 (2) in its spiral revolutions, commonly the anterior end described a 

 wide spiral, (3) circus movements to the right were markedly less 

 common as was also (4) the occurrence of the avoiding reaction, and 

 (5) periods of quiet were more frequent and of much longer duration. 

 Upon examining with high power the movements of the membranelles, 

 a difference in rhythm was frequently conspicuous between the series 

 on the left side of the cut and those on the right side. The former 



