ARTIFICIAL RHYTHM. 193 



If a paral3^zed nectocalyx, while manifesting its 

 artificial rhythm in acidulated sea-water, be sud- 

 denly transferred to normal sea- water, the move- 

 ments do not cease immediately, but continue for 

 a considerable time. This fact can easily be ex- 

 plained by the very probable, and indeed almost 

 necessary, supposition that it takes some time after 

 the transference to the normal saa-water for the 

 acid to be washed out from contact with the ex- 

 citable tissues. Sooner or later, however, as we 

 should expect, in the normal sea-water the rhythmic 

 movements entirely cease, and the bell becomes 

 quiescent, with a normal irritability as regards 

 single stimuli. If it be now again transferred to 

 the acidulated water, after a short interval the 

 rhythmic movements will again commence, and so 

 on during several repetitions of this experiment, 

 until the irritability of the tissues has finally 

 become destroyed by the influence of the acid. 



Other chemical irritants which I have tried pro- 

 duce substantially similar effects on the paralyzed 

 bell of Sarsia. I shall, therefore, only wait to 

 describe the influence of one of these irritants, the 

 action of which in some respects diflers from that 

 of acids, and which I have found to be one of the 

 most unfailing in its power to produce the rhythmic 

 movements in question. This irritant is glycerine, 

 and in order to produce its full effect it requires to 

 be added to the sea-water in about the proportion 

 of five per cent. The manifestation of artificial 

 rhythm in solutions of this kind is quite unfailing. 

 It begins after an exposure of from fifteen to thirty 



