VOETICELLA. 11 



e. The pharynx is a narrow continuation of the inner 



end of the vestibule, extending deep into the 

 endosarc. 



f. The anus is a small opening into the vestibule, 



visible only at the moment of extrusion of fsecal 

 matter. 



g. The cilia are arranged in an incomplete ring round 



the margin of the disc, in the groove between the 

 disc and peristome : they also line the vestibule 

 and pharynx. They produce a current which 

 runs round the disc in the direction opposite to 

 that of the hands of a watch, then down the 

 vestibule near its ventral surface, and, after a 

 turn in the upper part of the pharynx, up along 

 the dorsal wall of the vestibule to the exterior. 

 The appearance of a long ' vestibular seta ' in the 

 dorsal part of the vestibule is due to the move- 

 ments of the vestibular cilia. The cilia serve 

 to sweep food particles into the interior of the 

 animal. 



h. Food-vacuoles, enclosing food particles, may often 

 be seen circulating in the endosarc. 



1. The pulsating vacuole is a spherical cavity, situated 

 between the disc and the vestibule, and opening 

 into the latter. It pulsates rhythmically. 



k. The nucleus is an elongated curved rod lying in 

 the endosarc, about the middle of the body. 



1. A longitudinal ' myophan ' striation is visible in the 

 deeper layer of the ectosaro, especially at the 

 proximal end of the body, close to the stalk. 



2. The stalk. 



a. The cuticle forms a thick covering to the stalk : 



to its elasticity the straightening of the stalk 

 after contraction is probably due. 



b. The contractile band running down inside the 



cuticular sheath of the stalk is continuous above 



