182 
MR. G. J. ROMANES ON THE LOCOMOTOR SYSTEM OE MEDUSAE. 
Fig. 5. 
During the whole progress of such experiments the faradaic stimulation was, of 
course, kept of uniform intensity; so that the progressive acceleration is undoubtedly 
due to the increase of temperature alone. With each increment of temperature 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 influence that any given degree of temperature exerts on the rate of 
the natural and of the artificial rhythm respectively ; for it will be remembered that 
in warm water the natural rhythm, besides being quicker, is not so regular as it 
is in cold water ; thus also it is with the artificial rhythm. Again, water below 20° or 
above 85° suspends the natural rhythm, i.e., stops the contractions; and the artificial 
rhythm is suspended at about the same degrees. Lastly, just as there are considerable 
individual variations in the extent to which the natural rhythm is affected by tem¬ 
perature, so the artificial rhythm is in some cases more affected by this cause than 
in others, though in all cases it further resembles the natural rhythm in showing some 
considerable decree of modification under the influence of this cause. 
© 
On the whole, then, it would be impossible to imagine two cases more completely 
parallel than are these of the effects of temperature on natural and on artificial rhythm 
of contraction. To render apparent tlie degree in which these effects are produced, I here append a pair 
of tracings which were procured from the same piece of tissue when exposed to the different temperatures 
named. (N.B.—The seconds are wrongly marked in fig. 8, they ought to he the same as in fig. 7.) 
