106 JELLY-FISH, STAR-FISH, AND SEA-URCHINS. 
more locomotor contractions. If in the latter case 
the stimulus be not too strong, or, better still, if the 
specimen operated on be in a non-vigorous or in 
a partly aneesthesiated state, it may be observed 
that a short interval elapses between the response 
of the tentacles and that of the bell. Lastly, the 
manubrium is much more sensitive to a stimulus 
‘applied to a tentacle, or to one of the marginal 
bodies, than it-is to a stimulus applied at any other 
part of the nectocalyx. 
These facts clearly point to the inference that 
nervous connections unite the tentacles with one 
another and also with the manubrium; or, perhaps 
more precisely, that each marginal body acts as 
a co-ordinating centre between nerves proceeding 
from it in four directions, viz. to the attached 
tentacle, to the margin on either side, and to the 
manubrium. This, it will be observed, is the distri- 
bution which Haeckel describes as occurring in 
Geryonia, and Schultz as occurring in Sarsia. It is, 
further, the distribution to which my explorations 
by stimulus would certainly point. But, in order 
to test the matter still more thoroughly, I tried the 
effects of section in destroying the physiological 
relations which I have just described. These effects, 
in the case of the tentacles, were sufficiently precise. 
A minute radial cut (only. just long enough to 
sever the tissues of the extreme margin) introduced 
between each pair of adjacent marginal bodies 
completely destroyed the physiological connection 
between the tentacles. If only three marginal cuts 
were introduced, the sympathy between those two 
