202 JELLY-FISH, STAR-FISH, AND SEA-URCHINS. 
substantiate the view I am endeavouring to uphold, 
viz. that the natural rhythm may be a function 
of the contractile as distinguished from the gang- 
lionic tissue. Of the modifying causes in question, 
the first that I tried was temperature. 
Having already treated of the effects of tem- 
perature on the natural rhythm, it will now be 
sufficient to say that we have seen these effects to 
be similar to those which temperature exerts on 
the rhythm of ganglionic tissues in general. Now, 
I find that temperature exerts precisely the same 
influence on the artificial rhythm of deganglionated 
tissue as it does on the natural rhythm of the un- 
mutilated animal. To economize space, I shall only 
quote one of my observations in a table which ex- 
plains itself. I also append tracings of another obser- 
vation, to render the difference in the rate of the 
artificial rhythm more apparent to the eye (Fig. 28). 
Temperature of water Number of contractions 
(Fahr.). per minute. 
25° 24 
45° 40 
72° 60 
During the whole progress of such experiments 
the faradaic stimulation was, of course, kept of 
uniform intensity; so that the progressive ac- 
celeration is undoubtedly due to the increase of 
temperature alone. With each increment of tem- 
perature the rate of the artificial rhythm increases 
suddenly, just as it does in the case of: the natural 
rhythm. Moreover, there seems to be a sort of 
rough correspondence between the amount of in- 
