1888-89.] Mr G. N. Stewart on Electrotonic Variation. 245 
of nerve in the longitudinal direction is a constant. Of course it will 
vary slightly even for the two nerves of the same frog, as it will 
depend mainly at least upon the amount and kind of the dissolved 
crystalloids. In my former results on the intrapolar effect I found 
that the limiting electromotive force varied from 8 to 9 Daniells, 
when the length of nerve was from 12 to 14 mm. The two sets of 
experiments therefore agree as well as one is entitled to expect in 
observations of this sort. The strength of stimulus, of course, has 
also to be taken into account. 
Experiments 12 and 13 show how the effect in the extrapolar 
region reaches a maximum, while in the intrapolar it declines to a 
minimum. This of itself is quite enough to dispose of the pos- 
sibility that the suppression of the intrapolar effect is due to the 
decline of excitability at the point of stimulation through the spread 
of anelectrotonus. 
Experiment 14 is an example of stimulation on the cathodic side. 
Fig. 6. 
Fig. 6 shows the curve of the effect in Experiment 12 plotted to 
scale. 
The number of points are too few to determine the details. 
Almost the whole of the ascent lies very nearly in a straight line. 
