1922] Bees: The Ncuromolor Apparatus of Paramaccium 343 



cytopharyns is near the posterior contractile vacuole and ends 

 abruptly at the endoplasm where the food vacuoles form. 



There are two membranelle zones in the cytopharynx, one of 

 which, the anterior, was described (Maier, 1903) as an undulating 

 membrane. But careful studies of cross as well as longitudinal sec- 

 tions and also of the living animal lead us to believe that this zone is 

 made up of a series of flat, paint-brush-like membranelles rather than 

 connected longitudinal rows of cilia such as would constitute an 

 undulating membrane (pi. 33, figs. 9, 10; pi. 35, figs. 21, 23). 



The anterior zone extends from the beginning of the cytopharynx 

 to the enlargement. Except in the posterior region, the cilia of each 

 membranelle are of about equal length, but at the enlargement each 

 brush becomes progressively longer. 



A fan of heavy fibers, each of which is of about twice the diameter 

 of a peripheral fiber, runs from the neuromotor center directly to the 

 anterior membranelle zone of the cytopharynx. Some of these fibers 

 may be seen in the living unstained animals as well as in most whole 

 mounts and cross and longitudinal sections. One gets an exceptionally 

 good view in thick well destained longitiidinal sections (pi. 35, fig. 22). 



Two of the fibers, on the right margin of the fan, are heavier than 

 the others. In thin cross-sections of the cytopharynx a structure 

 made up of basal granules is seen resembling a basal plate (pi. 33, 

 fig. 10). Maier (1902) describes this plate but does not mention the 

 fibers. The two hea\'y fibers above mentioned run along the margins 

 of each plate. All the fibers of the fan are about equidistant, almost 

 parallel, and do not branch. They have not been traced positively 

 beyond the anterior membranelle zone. 



The posterior membranelle zone is less regular in outline than the 

 anterior, and less extensive. It was clearly seen first in a section 

 fifteen microns thick stained with Mallory's. This zone begins as a 

 series of narrow, rounded, paint-brush membranelles just anterior to 

 the enlargement on the left side of the cytopharynx. Farther pos- 

 teriorly in the enlargement it spreads out on the indented surface, 

 the basal granules of its cilia being in the oral side (pi. 33, fig. 11 ; 

 pi. 85, figs. 21, 23). So far as is known, this posterior membranelle 

 zone has not been previously described. 



Two fibers were noted above (page 342) running from the neuro- 

 motor center in each margin of the eytostome to the basal granules of 

 the peristomal cilia and on into the cytopharynx. They run into the 

 posterior membran'elle zone (pi. 35, fig. 26) and branch profusely 

 even into the endoplasm beyond it. 



