732 ME, Gr. J. ROMANES ON THE LOCOMOTOR SYSTEM OE MEDUSAE. 
perceptibly impaired. I therefore continued the radial cuts, and found that when 
these reached one half or two thirds of the way up the sides of the inner bell (or 
contractile sheet), the coordination became visibly affected, and this for the first 
time. These experiments, however, did not satisfy me that the coordination was not 
chiefly, or exclusively, due to the marginal nerves ; for the bell of Sarsia is so small, 
and contractile waves are in this genus so rapid, that the following hypothesis still 
remained open. When the whole margin of Sarsia is removed and the paralyzed bell 
stimulated, so far as the eye can judge the resulting contraction is simultaneous over 
the entire bell. Whether this rapid conduction of contractile influence from the seat 
of stimulation to all the other parts of the bell is due to muscle or to nerve, is here of 
no consequence ; for, in view merely of the fact of such rapid conduction taking place, 
it follows that when the four short radial cuts are introduced, even if these cuts destroy 
all the nerves by which the ganglionic coordination is effected, such coordination would 
still appear to be effected in consequence of the rapid conduction of a mere contractile 
wave over the whole muscle-sheet from the ganglion which first happens to discharge. 
And, if this is the correct interpretation, we should expect the loss of coordination first 
to become apparent when the radial incisions reach about halfway up the bell ; for, 
under this form of section, it is then only that a stimulus applied to the margin of a 
deganglionated , or paralyzed, bell can be seen to cause in the bell a rapid contractile 
wave as distinguished from an apparently simultaneous contraction of the entire muscle- 
sheet. Against this interpretation it may be urged, that even although the discharge 
of a ganglion thus isolated from its fellows would certainly give rise to the erroneous 
appearance of a coordinated discharge of all the ganglia, still, if coordination is destroyed 
by the short radial cuts, we should expect this destruction to become observable in con- 
sequence of the ganglia in the four quadrants of the bell discharging independently of 
one another as to time, and therefore as a total effect producing a flurried movement of 
the bell, instead of the single decided systole followed by a short but perfectly inactive 
period of diastole. This objection, however, though natural, is not, I think, valid ; for 
we have seen in the last section that, in the case of Aurelia, a contractile wave has the 
effect, when it reaches a locomotor ganglion, of causing the latter to discharge [§1(«)]; and 
the same thing is therefore presumably true in the case of Sarsia. Consequently, when in 
the latter genus ganglionic coordination has been destroyed by the four short radial 
cuts, and when any of the separated ganglia originates a discharge, all the other ganglia 
will immediately afterwards do the same, because stimulated by the passage of the con- 
tractile wave. Now, as all the ganglia were previously accustomed to act in consort, the 
time required for their nutrition after every discharge must be nearly or quite equal in 
the case of each of the ganglia ; so that when, after the physiological harmony has been 
destroyed, one of their number originates a discharge, and when, as a consequence, all 
the others immediately afterwards do the same, the degree of exhaustion will be nearly 
or quite equal in the case of all the ganglia ; and therefore the time that will elapse 
