214 HARRY BEAL TORREY. 



The disgorgement of non-nutritious bodies may now be briefly 

 considered. All harmless non-nutritious bodies, and all food 

 stuffs from which the nutrient juices have been taken during the 

 process of digestion, are sooner or later cast out of the mouth. 

 The cause of the ejection is to be found in the behavior, under 

 varying stimulation, of the oesophageal cilia. The mesenterial 

 filaments bordering the mesenteries, and the defensive filamentous 

 acontia, are ciliated, but probably take no part in the process, for 

 several reasons. 1 



First, the mesenterial filaments pursue excessively meandering 

 courses along the edges of the mesenteries, and their cilia pro- 

 duce many currents which are antagonistic instead of proceeding 

 in one general direction. I have not been able to determine 

 whether the cilia beat more strongly away from or toward the 

 mouth. In all parts of each filament, however, they appear to 

 beat in the same direction ; and this beat is not reversed by con- 

 tact with meat or meat juices. Second, the cilia on the acontia 

 beat always more strongly toward their free ends, and they too 

 do not reverse their beat in the presence of meat juices. Since 

 the acontia are attached by one end only, have a marked ten- 

 dency to coil, and occupy without regularity of arrangement any 

 position in the ccelenteron, they can hardly be concerned with 

 the phenomena of disgorgement. It may be noted in passing, 

 however, that when they are thrust through mouth or cinclides, 

 their cilia, in carrying toward their tips whatever foreign particles 

 may come in contact with them, are performing what must be in 

 the long run an advantageous service. 



Finally, the oesophagus itself, ordinarily more than half the 

 length of the column, reaches nearer to the foot disk when the 

 polyp contracts as it does with food substances within it. The 

 objects taken into the coelenteron never get far away from the 

 lower edge of the oesophagus. Under the influence of the mesen- 

 terial and acont'al cilia, they may, if small enough, rotate aim- 

 lessly about during the period of digestion and absorption. In 

 the absence of direct stimulation, the oesophageal cilia resume 



1 The following facts concerning the behavior of the cilia on mesenterial filaments 

 and acontia were obtained from Metri,/im>i, but I feel confident that the same results 

 would have followed an investigation of S. dbr'/.r/ had the supply of material permitted. 



