192 °] Taylor: Neuromotor Apparatus in Euplotes 423 



The discharge of the vacuole is clearly on the ventral side within 

 three or four microns of the right margin of the pellicle. This may be 

 observed with careful focusing when small food vacuoles are lying just 

 posterior to the point of discharge. The relative position of the last 

 trace of a systole, as compared with that of the food particles and 

 ventral pellicle, appears distinctly ventral. Also, this position may be 

 verified by applying the needle-point very lightly against the ventral 

 surface near the point of discharge, whereupon the position of the 

 discharge is ventral. 



Anal Aperture 



This has been located in E. patella on the ventral side slightly 

 posterior to the discharge pore of the contractile vacuole and within 

 five microns of the margin of the pellicle. It was first observed when 

 two frustules of Navicula were seen to pass successively from an animal 

 held in a shallow hanging drop. The emission of various other fecal 

 particles, mostly very small, has since been noted in several individuals. 

 Voiding apparently seldom occurs when the stress of surface tension 

 or the pressure of an applied needle is increased. In only three cases 

 has the emission of particles thus been observed. However, pressure 

 from the needle or from surface tension may sometimes cause the pro- 

 trusion of a small area including the anal pore. Griffin (1910a) 

 describes the location of an anal opening in E. ivorcesteri immediately 

 to the right of the outermost anal cirrus. This closely approximates 

 the position of the pore in E. patella, But the pore in E. ivorcesteri 

 is anterior to the contractile vacuole, whereas in E. patella it is pos- 

 terior. It should be said, however, that the position of the contractile 

 vacuole varies considerably in different E. patella which, of course, 

 somewhat alters the relations above referred to. 



Cirri 



The eighteen styliform cirri of Euplotes patella appear on the 

 ventral side in four fairly well defined groups. Yocom (1918) classifies 

 these into six frontal cirri, three ventral cirri, five anal and four 

 marginal cirri, which is in agreemnt with Stein (1859). While the 

 groups of frontal and ventral cirri are less clearly defined than are 

 the others, it is at least more convenient and, I believe, more accurate 

 to regard the frontal group as composed of seven, and the ventral 

 group of two cirri. Also, for further convenience in describing the 



