No. 3-] STUDY OF STENOSTOMA LEU CO PS O. SCHM. 277 



relaxation of the circular muscle fibres of the pharyngeal wall 

 combined with the contraction of the radial muscles which are 

 connected to the anterior end of the pharynx, while the pharynx 

 itself is held in place by the pharyngeal retractor muscles. 

 When waste material is extruded, the whole pharynx may be 

 brought forward, and the mouth and the valve between the 

 pharynx and intestine opened at the same time by the relaxation 

 of the pharyngeal retractor muscles and the contraction of all 

 the radial muscles. 



Stenostoma leiicops feeds on both animal and vegetable matter. 

 The greater part of its food, however, is vegetable matter. 

 Small algae are very often seen in the intestine. In the intes- 

 tine of one specimen I found a Difflugia and a small Crusta- 

 cean which was so broken up that it could not be identified. 



The food passes through the mouth and pharynx into the 

 intestine, where it remains until digested or extruded. After 

 milk has been fed to some of these worms for a short time oil- 

 globules may be seen in the lumen of the intestine and in the 

 intestinal cells. By dropping a drop of the milk into the water 

 it was fed to some worms which had been for some time previ- 

 ously in a watch glass of clean water. The milk did not mix 

 readily with the water. The worms swam to the uniting surface 

 between milk and water and quietly remained there while feed- 

 ing. Sometimes they darted through the thickest part of the 

 milk. They were left in this for fifty minutes, after which they 

 were put in pure water. When some of these worms were com- 

 pressed so that the intestinal cells were crushed out, the cells 

 were seen to contain each three or four oil-globules, while 

 scarcely more than one could be seen in the cells of worms of 

 the same lot which had not been so fed. Some of these worms 

 were treated with osmic acid and sectioned. When the sections 

 were studied, the outer ends of the cells were seen to be filled 

 with very small oil-globules. 



The three facts, — that the globules just mentioned are so 

 small, that when there is a large globule in the cell the small 

 ones are arranged around it, that when there are no small glob- 

 ules in the cell the large globules are very much larger than 

 the large globules in the cells which contain also the small 

 globules (p. 276) — point to the conclusion, that the oil first 

 appears in the cells in small globules which afterward unite to 

 form the large ones. 



