E. W. BERGEK ON THE CUBOMEDUS.E. 7 



One cannot help but remark how analogous is the behavior of 

 medusas, in respect to light and darkness, to the behavior of many 

 of the higher animals, and medusae are among the most lowly 

 organized of the animal creation. 



Were one to conclude from the behavior of Charybdea in light 

 and darkness in the laboratory, that it remained on or near the 

 bottom in the daytime but became more active near or at the 

 surface evenings, nights and early mornings, one would probably not 

 be far from the truth. Dr. Conant, while towing near the bottom 

 with a weighted net, in water four to five feet (1.2-1.5 m.) deep not far 

 from shore and deeper farther out, found Charybdea in abundance 

 mornings and afternoons, but very few in the evening. In the 

 evening some few were usually taken in the surface tow. (See Intro- 

 duction, Occurrence and Activity.) 



Again, who knows but that Charybdea is active during the day, 

 on the bottom where it was dredged (the light there would only be 

 moderate), and quiet at night. This supposition would seem to be 

 true, at least, for those forms of Cubomedusse that live in deep 

 water. We can hardly suppose that they should regularly rise to 

 the surface from great depths and become active. This much we do 

 know that bright light inhibits Charybdea's activities, while it 

 probably would not be active in perfect darkness. 



I do not know just what interpretation to put upon Conant's 

 finding Charybdea at Port Henderson at the surface during the 

 early part of the forenoon, before the sea-breeze roughened the water 

 ("Cubomedusffi" p. 7). This fact hardly fits in with my conclusions 

 above. Perhaps Charybdea's habits vary with its habitat. 



Finally, while I find no experimental evidence in Conant's notes 

 about what parts of Charybdea are sensitive to light, yet it would 

 seem preposterous, from histological evidence and from Romanes' 

 results on Sarsia, to doubt that the eyes of the marginal bodies are 

 the seat of this stimulation. 



Dr. Conant further experimented by cutting off certain organs 

 and parts from the Cubomedusan bell. These excisions consisted 

 chiefly in cutting out the concretions of the sensory clubs, cutting off 

 the whole club, eliminating a part or whole of the margin and the 

 velarium, cutting the bell into sectors, excising the stomach and 

 parts connected with it, and other parts. 



