CO-ORDINATION, 141 
The next experiment I tried was to make four 
short radial incisions in the margin as _ before 
described, and then to continue one of these in- 
cisions the whole way up the bell. By careful 
observation I could now perceive that all the 
marginal ganglia did not discharge simultane- 
ously ; for when those situated nearest to the long 
radial cut happened to take the initiative, the 
resulting contraction-wave, having double the dis- 
tance to travel which it would have had if the long 
radial cut had been absent, could now be followed 
by the eye in its very rapid course round the bell. 
Now, the fact that in this form of section I was 
able to detect the passage of a wave, proves that 
the three short radial sections had destroyed the 
co-ordinated action of the marginal ganglia. 
From these experiments, then, I conclude that in 
this genus ganglionic co-ordination, in the strict 
sense of the term, is effected exclusively by means 
of the marginal nerves. And as these experiments 
on Sarsia are exceedingly difficult to conduct, owing 
to the very rapid passage of contraction-waves in 
this genus, it is satisfactory to find that this con- 
clusion is further supported by the analogy which 
the other species of naked-eyed Meduscze afford, and 
to the consideration of which we shall now proceed. 
The effects of four short radial incisions through 
the margin of any species of Tiaropsis, Thaumantias, 
Staurophora, etc., are usually very conspicuous. 
Each of the quadrants included between two adjacent 
incisions shows a strong tendency to assume an 
independent action of its own. This tendency is 
