ARTIFICIAL RHYTHM. 193 
If a paralyzed 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 sea-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 pre- 
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 differs 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 
