FEEDING REACTIONS IN DILEPTUS GIGAS. 



135 



readily ingested by the dileptus (Fig. 5, G, b). Thus, now here, 

 now there, the stentor gives up part of its protoplasm and each 

 part is eaten by the little dilepti, which sometimes more than treble 

 in size after feeding on this organism. Meanwhile the stentor 



H 



FIG. 5. Sketches illustrating effects of trichocysts of Dileptus on Stentor 

 caeruleus. A-I, successive stages. A, normal stentor with epanded peristome 

 (a). When stimulated as by contact with aboral surface of dileptus, the stentor 

 contracts slightly as shown in B. If the oral surface of the proboscis comes 

 in contact (C) the stentor contracts vigorously and its protoplasm in the re- 

 gion of contact O) soon protrudes, D, E, and F. The injured area (e) soon 

 gelates and the protruding mass (6) is constricted off, frequently being ingested 

 by the dileptus (G). The stentor remains contracted for some time, but event- 

 ually, unless repeatedly attacked, it expands completely (/) and appears to be 

 entirely normal. 



