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 

 sufiicient 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). 



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- 



