1922] Rces: The Neuromotor Apparatus of Paramaecium 339 



membranelles of the cytopharynx and the motor and defensive 

 organelles covering the surface of the body have been found to be 

 connected by an integrated fibrillar system which has its center in 

 the outer endoplasm at the anterior end of the cj^tostome. 



Maupas (1883), Biitschli (1887-89), Kiilsch (1902), Maier (1903), 

 Schuberg (1907), and Khainslcy (1910) have described the pellicle 

 of Paramaecium. All are agreed that the cilia arise from depressions 

 in the surface, while the Indian club-shaped trichocysts pierce 

 deeply into the ectoplasm and reach the surface of papillae arranged 

 in a definite pattern. The fact that the ciliary and trichocyst lines 

 are not parallel was also discovered. They were described by 

 Biitschli (1889) as " rechtwinklig gekreuzt." Maupas describes the 

 pellicle as a pattern of rhombohedral plates, the cilia being in the 

 center, the trichocysts in the corners of these plates. Biitschli, 

 Kolsch, and Maier thought the plates were hexagonal. Schuberg 

 found rhombohedrons, hexagons, and parallelograms. Khainsky's 

 observations confirm those of Schuberg. 



But it is only when one makes maps of the entire pellicle that the 

 true relationships of these various patterns are revealed and the 

 idea of grooves and ridges rather than depressions and papillae is 

 obtained. The terminology employed by Kofoid and Swezy (1919) 

 to describe Trichonympha campanula is here employed to describe 

 Paramaecium. In Trichonympha the cilia arise from the ridges, in 

 Paramaecium they arise from the grooves, but in both animals they 

 are arranged in longitudinal rows. On the aboral surface of the latter 

 they are almost parallel; on the oral side, slightly oblique and the 

 rows from opposite sides meet in a series of V 's. The apices of these 

 V's lie in a line that runs longitudinally through the eytostome and 

 hence obliquely through the oral surface from the anterior to the 

 posterior end. This is the ciliary suture (fig. A, a;., also pi. 35, fig. 26, 

 and pi. 36, fig. 30). 



The ridges differ from those of Trichonympha in that they are not 

 parallel, but are arranged with reference to the neuromotor system 

 in whorls (figs. A and B, also pi. 35, figs. 27, 28, and pi. 36, figs. 31, 

 33). For this reason, they are cut across at regular intervals by the 

 grooves so that they appear as papillae which constitute interrupted 

 ridges. It is the intercrossing of these whorls of trichocysts and rows 

 of cilia that gives the various rhombohedral, hexagonal, and paral- 

 lelogrammie patterns previouslj' described. The courses of the whorls 

 being the same as those of the neuromotor fibers, it will not be 

 necessary to describe them separately. 



