440 University of California Publications in Zoology [Vol. 19 



Removal of marginal cirri. — These, due to their exposed position, 

 were readily snipped off with the needle. The excised parts thereafter 

 wjre never observed to beat. But when one, two, three or all were 

 removed with some of the body plasm the cirri continued lashing very 

 rapidly and driving the piece deviously through the water until death, 

 which followed a few minutes later. When an excision (properly, 

 a transection) of the caudal end was made to include all four marginal 

 cirri, the piece revolved very rapidly with the cut surface as an 

 axis but in such manner as to move speedily through the water with 

 the left side foremost. Such removal or the snipping off of some 

 or all of these cirri did not apparently modify the several swimming 

 or creeping movements of the normal animal. If, however, these cirri 

 had been removed from an animal which was then transected just 

 anterior to the anal cirri, the posterior part usually rotated rapidly, 

 the cut surface as its axis, for several minutes. Circus or spiral 

 movements were at no time observed. But within an hour after 

 becoming quiet it w r as irresponsive to mechanical stimuli and did not 

 resort to rotating movements again. The anal cirri lashed feebly, 

 very irregularly and ineffectively. 



Excision of frontal cirri. — Owing to the length of these cirri and 

 the extension of four of them beyond the right lateral margin of the 

 body the four may be snipped off with a V-shaped needle. Thereafter, 

 the animal very seldom attempts creeping and its spiral movements 

 are abnormal. In the latter instance, its anterior end rotates in a 

 larger spiral than that of the posterior end. In two cases all but one 

 frontal cirrus were either snipped off or removed by inserting the 

 needle-point at the base of each cirnis, thus to gouge them loose. These 

 cirri came off rather readily. Three of them beat several times follow- 

 ing their detachment. In each case the animal could not creep, but 

 frequently swam slowly in circuits, or in spiral movements with the 

 anterior end describing spirals which were about tw-ice the diameter 

 of those of the posterior end. No discernible injury resulted from 

 gouging out these cirri ; the movements of both the membranelles and 

 anal cirri were apparently normal. In a few instances, the animal 

 gave the avoiding reaction upon stimulation of the oral lip with the 

 needle-point, although these were feeble and abnormal. However, both 

 animals died within forty-eight hours without regenerating new frontal 

 cirri. Their death may have been due directly to injuries from the 

 excisions or indirectly to infections or other causes. 



Excision of anal cirri. — Infrequently, E. patella were found with 

 fully half of the anal cirri extending beyond the caudal margin of the 



