E. W. BERGER ON THE CUBOMEDUS^E. 17 



Stimulation. Romanes found when he stimulated a deganglionated 

 bell of a Hydromedusa, that it responded by a single contraction, 

 while that of a Scyphomedusa responded with several quite rhythmic 

 contractions. Charybdea in this respect agrees with the Scyphome- 

 dus*. Romanes' results were also verified on Aurelia. (Experiments 

 12c, 15, 50, 51.) 



Activity of Charybdea. In speaking of the activity of Charybdea, 

 I cannot do better than refer the reader to the notes. (Experiment 

 41.) Conant remarks in his dissertation what an active swimmer 

 Charybdea is, and this is further borne out by his later observations. 



Temperature. Ice in the water seemed to have no effect, except 

 when held against an animal, when a slowing of pulsation followed 

 in a few instances. On some pulsating actively in the sun the 

 temperature of the water was found to be 92 F. (Experiments 33-35.) 



Conant does not tell us how cold the water became when he 

 placed ice in it, but judging from his results, it seems that he might 

 have obtained a decided slowing of pulsation if the water in which 

 the medusae swam had been permitted to approach anywhere near 

 the freezing point, say 35-40 F. Romanes obtained decided slowing 

 of pulsation, and even complete inhibition, on a bell of Aurelia, as 

 also a lengthening of the latent period on some strips cut from a 

 bell of Aurelia, by lowering the temperature of the water. Replacing 

 Aurelia in warmer water had the effect of immediate recovery and 

 increased rhythm. In Aurelia, raising the temperature increased the 

 rhythm but diminished it when the temperature of the water became 

 70-80 F. After a slowing of pulsation due to such a rise of temper- 

 ature, it would not quicken again when the animal was placed in 

 water of its normal temperature. Romanes explains this by supposing 

 that the tissue of the medusa had been permanently injured by the 

 abnormally high temperature. It would be interesting to observe 

 how the tropical Aurelia behaved under such treatment, seeing that 

 Charybdea pulsated actively and without apparent injury in water at 

 92 F. Limnocodium, noted by Romanes, and probably a tropical 

 species, lived happily in water at 85 F. in the lily house of the Royal 

 Botanical Society. The temperature of the water could be raised to 

 100 F. before it proved fatal to this medusa. Such facts point to a 

 decided difference in the constitution of the protoplasm of tropical and 

 2 



