84 Asa Arthur Schaefjer 



by the combined action of the ciha and the compressive movement 

 of the walls, of the pouch and funnel. The general bodv cilia 

 play the least important part in the securing of food. They are 

 distributed in rows over the surface of the Stentor included 

 between the foot and the edge of the disk. Their chief function 

 is that of locomotion. But w^hen the Stentor is attached, their 

 backward or footward beat helps to get rid of the water flowing 

 over the edge of the disk which no longer contains food, and also 

 carries out of reach of the vortex those particles which are dropped 

 over the edge of the pouch in the mid-ventral notch. By this 

 means the vortex always consists of water and particles which for 

 the most part had not struck the disk before. The body cilia thus 

 serve to increase the food-getting ability of the Stentor. This 

 constitutes the normal action of all the cilia of a normal attached 

 Stentor under usual circumstances when ingesting food. 



BEHAVIOR IN REJECTING PARTICLES 



The rejection of a particle is accomplished by various modifica- 

 tions of the ciliarv movements outlined above, depending upon the 

 strength of the stimulation. In the simplest case the rejection of 

 a particle is produced by a reversal of the cilia in the pouch, or in 

 the funnel, or in both. There is much variation even in this 

 apparently simple method of getting rid of an objectionable par- 

 ticle. The course of the particle mav be altered at any stage in 

 passing from the interior surface of the pouch to the mouth open- 

 ing at the bottom of the funnel. If the substance is a small sand 

 grain, e. g., the course is in almost ever; case altered before the 

 funnel opening is reached. That is, the sand grain is ejected by a 

 strong, presumably outward, beat of the pouch cilia. The funnel 

 cilia play no part in such an instance, as may be seen occasionally 

 when there is a food particle in the funnel at the time there is a 

 sand grain in the pouch. The sand grain is ejected while the food 

 particles in the funnel are ingested. When the substance is one like 

 a starch grain, or a grain of carmine, or a food particle when the 

 Stentor is not "hungry," the course of the particle may be altered 

 anywhere from the interior surface of the pouch to the mouth open- 



