5° 



H. G. Kribs 



to the mucus tracts and excretory masses more largely when the 

 food supply is scarce. Under such conditions, when one ^olo- 

 soma comes in contact with another the "feeding reactions" are 

 mutually exhibited. They also get more or less stuck together 

 by the adhesive mucus. If several get stuck together in this way 

 the difficulties of separation become serious. This leads to what 

 has been termed a "grouping" of ."Eolosoma. 



The secretion of mucus may be also of protective significance. 

 An i^Lolosom a was seized near the middle segments by one of the 

 tentacles of an hydra. Immediately there was a violent end to 

 end contraction of the body wall, in which large quantities of 

 mucus and numerous oil globules were extruded. This stuff 

 seemed to thicken considerably upon contact with the water. In 

 a few moments the /Eolosoma was able to squirm away with a 

 spiral stretching movement leaving the mucus and globules in 

 the grasp of the hydra. This heavy extrusion of mucus and glob- 

 ules was probably stimulated by the stinging cells oi the hvdra, 

 as similar reactions are readily obtained with strong acid or alkali 

 stimulations. These phenomena closely resemble the discharge 

 of trichocystt by paramoecia under chemical stimulations (Mas- 

 sart 'oi); or when attacked by Didinium (Mast '09). Both 

 of these authors assume that the trichocysts function as organs 

 of defense. 



^'Eolosoma come out more actively for food during the night. 

 Many may be seen in the early hours of the morning feeding about 

 the sides of the jar. On a bright day, when the jar is not pro- 

 tected from the light, they gradually seek refuge among the debris 

 at the bottom of the jar. If the jar then be carefully covered 

 over, in a few hours they come out of their hiding place and feed 

 as before. When they are put into a clear glass dish on the stage 

 of the microscope and bright light turned upon them from beneath 

 they move about so actively that it is most difficult to observe 

 them carefully. If a blue glass is placed beneath them and the 

 source of light their movements are noticeably accentuated. 

 Ultra-violet light (-^275) destroys them in a few moments. Little 

 change in their behavior, if any, was induced by red light. If a 

 number of .^olosoma are placed in a clear glass dish and subjected 



