MB. Gr. J. BO MANES ON THE LOCOMOTOB SYSTEM OE MEDUSA). 
695 
physiological relations which I have just described. These effects, in the case of the 
tentacles, were sufficiently precise. A minute radial cut introduced between each pair 
of adjacent marginal bodies — there being thus four such cuts in all — as a rule com- 
pletely destroyed the physiological connexion between the tentacles ; or if, as in some 
cases, such connexions were not completely destroyed by this operation, they were at least 
conspicuously impaired. If only three marginal cuts were introduced, the sympathy 
between those two adjacent tentacles between which no cut was made continued unim- 
paired, while the sympathy between them and the other tentacles was either destroyed 
or greatly impaired. In all cases where the sympathy between tentacles was not wholly 
destroyed, but merely impaired, the impairment showed itself in this way. Whereas 
before the introduction of the radial cuts the slightest nip of one tentacle caused an 
instantaneous response on the part of all the tentacles, after the operation such a sti- 
mulus applied to one tentacle would perhaps cause no effect at all on the other tentacles, 
though on gently pulling one of the tentacles the others would retract at the same time 
as the bell, in response to this severe stimulus, would give a locomotor contraction. 
And as, before mutilation, the tentacles may be observed to respond to such a stimulus 
an exceedingly short time before the bell, I conclude that, after mutilation, the time 
required for the stimulus to pass round the margin from one tentacle to the others is 
increased. Hence the cases in which the sympathy between the tentacles is not wholly 
destroyed by the four minute radial cuts are, I think, to be regarded as cases in which 
those quadrants of the margin which have been physiologically separated from beneath 
nevertheless continued united to each other from above. And this junction I conceive 
to be effected by means of nerve-loops which are composed of smaller fibres than those 
of the margin, and which maybe supposed to join the artificial quadrants of the margin 
by traversing the muscular tissue of the bell in all directions above the level that is 
reached by the short radial cuts'*. 
(C) Nervous connexion between the Tentacles and the Poly pit e of Sarsia. — Having 
obtained such definite results in the case of the tentacles, I expected to do the same in 
the case of the polypite. Accordingly I began by severing one of the nutrient tubes 
across its diameter, and then nipping the tentacle at the end of that tube. The polypite 
responded as before. Knowing from my previous experiments that the stimulus escaped 
round the margin of the nectocalyx, I thought it probable that the reason why the polypite 
now responded was because the stimulus found its way up the three unsevered tubesf. 
I therefore divided all the four nutrient tubes ; but the polypite still continued to respond 
to a stimulus applied to any of the tentacles. Next, in the same specimen, I made two 
radial cuts, one on each side of a marginal body, and then irritated the tentacle attached 
to that body ; the polypite contracted as before. Lastly, I treated the other three 
* In the foregoing and subsequent descriptions, by “ short radial cuts ” I mean cuts which are only just long 
enough to sever the tissues of the extreme margin. 
f Eor the sake of brevity I speak of the nutrient tubes as themselves the excitable tracts, although anato- 
mically, no doubt, these tracts are distinct from the nutrient tubes. 
