138 JELLY-FISH, STAR-FISH, AND SEA-URCHINS. 
rhythm of the ganglion, which had previously been 
twenty in the minute, fell to fourteen for the first 
minute, eighteen for the second, and the original 
rate of twenty for the third. In such experiments 
the diminution of rate is most conspicuous during 
the first fifteen or thirty seconds of the first minute. 
Sometimes there are no contractions at ail for the 
first tifteen seconds after cessation of the stimulating 
process, and in such cases the natural rhythm, 
when it first begins, may be as slow as one-half or 
even one-quarter its normal rate. All these effects 
admit of being produced equally well, and with less 
trouble, by faradizing the strip, when it may be 
even better observed how prolonged may be the 
stimulation, without causing anything further than 
such slight exhaustion of the ganglion as the above 
results imply.* 
Naked-eyed Meduse. 
It would be impossible to imagine movements on 
the part of so simple an organism more indicative 
of physiological harmony than are the movements 
of Sarsia. One may watch several hundreds of 
these animals while they are swimming about in 
the same bell-jar and never perceive, as in the 
covered-eyed Medusve, the slightest want of gang- 
* In this description I have everywhere adopted the current 
phraseology with regard to ganglionic action—a phraseology 
which embodies the theory of ganglia supplying interrupted stimu- 
lation. But although I have done this for the sake of clearness, 
of course it will be seen that the facts harmonize equally well 
with the theory of continuous stimulation, to which I shall allude 
further on. 
