410 University of California Publications in Zoology [Vol. 19 



the pharynx. The remaining external organelles embrace eighteen 

 styliform cirri. Of these, four are caudal and fourteen ventral in 

 position. The right anterior ventral surface bears nine cirri, of which 

 six are termed frontal and three ventral cirri. The remaining five of 

 those ventral in position, known as anal cirri, are the largest and 

 longest and are the most important. These have their origin at the 

 ends of the five ventral grooves about twenty-five microns from the 

 posterior end, and extend backward beyond the caudal margin of the 

 body. 



All the cirri were observed by Yocom, in agreement with Maupas 

 (1883) and Griffin (1910), to be composed of cilia with distinct basal 

 granules. The component cilia are imbedded in a dense plate of ecto- 

 plasm just beneath the pellicle, the plate serving as a firm support for 

 the cirrus. Now from the basal plate of each anal cirrus there extends 

 a fiber toward the anterior end. These fibers were first seen and 

 figured by Maupas (1883) who briefly described them as joining the 

 five anal cirri and extending forward to converge and unite into a 

 single thread which disappeared near the anterior end of the animal. 

 In 1903 Prowazek found similar fibers in Euplotes harpa and Griffin 

 (1910) described such fibers for E. worcesteri. Yocom, how T ever. was 

 able to trace the fibers in E. patella farther forward to where they join 

 one end of a very small bilobed body, "the motorium." "It was first 

 seen as a dark body in animals stained with iron-alum haematin, lying 

 close to the right anterior corner of the triangular cytostome. In 

 specimens which are well destained this body is seen to be composed of 

 very fine granules closely grouped together, but if too dark it has the 

 appearance of an almost homogeneous body. "When stained with 

 Mallory's stain the motorium becomes bright red from the acid fuchsia 

 and lacks the granular appearance characteristic of specimens colored 

 with haematin. Plate 14, figure 5 (mot.) shows that this motor mass 

 does not have a smooth contour, but rather that it has ragged edges 

 with processes extending out into the surrounding ectoplasm" (Yocom, 

 1918, p. 355). The motorium is about eight microns long and, as 

 figured, about one-fourth as wide as it is long. Joining its left end are 

 the five long fibers from the anal cirri. These fibers converge and 

 appear to unite with the motorium as a single strand. 



From the right end of the motorium another fiber, the anterior 

 cytostomal fiber, was found to pass anteriorly and to the left along 

 the proximal border of the oral lip and the bases of the membranelles 

 throughout the entire series. Within the oral lip was observed a 





