No. 3.] STUDY OF STENOSTOMA LEUCOPS O. SCHM. 279 



ahnlichen Auslaufer der Amoben zum Umfassen und Aufnehmen 

 der Nahrungsobjekte dienen." 



The fact that the so-called cilia (Graff) at the distal ends of 

 the intestinal cells of Stenostoma lencops as observed by me 

 are very much thicker than the ordinary cilia, and that in sec- 

 tions they may be seen to have fused, together with the fact 

 that I have seen them in the living cells to have been retracted 

 and replaced by blunt pseudopodia, shows that they are as 

 Bohmig surmises, pseudopodia-like protoplasmic processes 

 rather than true cilia. 



I have no direct observations as to the participation of these 

 processes in the taking of food particles, but the facts stated 

 above, together with the fact that the cells which are filled with 

 food particles (milk globules in Stenostoma lencops and blood 

 corpuscles in Planarians according to Metschnikoff) are much 

 larger than cells not so filled are usually taken as evidence of 

 such participation. 



Graff ('82, p. 259) divides the part of the alimentary canal of 

 Stenostoma leucops between the opening at the ventral surface 

 of the body and the anterior end of the intestine into a poste- 

 rior oesophagus free from pharyngeal cells and an anterior 

 pharynx into which alone the pharyngeal cells open. As this 

 division is based on the openings of the pharyngeal cells only, 

 and as I have shown that these cells in Stenostoma lencops 

 open along the entire length of that part of the alimentary canal 

 between the cone-shaped depression and the intestine, this part of 

 the tube according to Graff should be designated as the pharynx. 



Graff ('82, p. 88), basing his conclusions on the development 

 of the pharynx of Stylochopsis (a Polyclad) as described by 

 Goette ^1^2) and on his own observations on the formation of 

 the new pharynx in the budding Microstoma, believes that 

 the entire pharynx of the Rhabdocoels is to be regarded as a 

 depression of the body wall and therefore lined with ectoderm. 

 He believes that the pharyngeal apparatus is homologous 

 throughout the Tubellaria, although he admits that without 

 a knowledge of its development it is impossible to place this 

 homology on a sound basis. 



Hallez ('79) as abstracted by Korschelt and Heider ('90, p. 114) 

 says the pharynx of Rhabdocoels appears to be derived from 

 the entoderm. 



