140 JELLY-FISH, STAR-FISH, AND SEA-URCHINS. 
previous observations on the physiological harmony 
subsisting between the tentacles, I was led to expect 
that the co-ordination of the locomotor ganglia was 
probably effected by means of the same tissue-tracts 
through which the intertentacular harmony was 
effected, namely, those situated in the margin of the 
bell. Accordingly, I introduced four short radial 
cuts, one midway between each pair of adjacent 
marginal bodies. The co-ordination, however, was 
not 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 co-ordina- 
tion became visibly affected, and this for the first 
time. 
I also tried the following experiment. Instead 
of beginning the radial cuts from the margin, I 
began them from the apex of the cone; and I found 
that however many of such cuts I introduced, and 
however far down the cone I carried them, so long 
as I did not actually sever the margin, so long did 
all the divisions of the bell continue to contract 
simultaneously.* This fact, therefore, proves that 
the margin of the bell is alone sufficient to maintain 
co-ordination. 
* This could be particularly well seen if, after the extreme 
apex of the cone had been removed, one of the four radial cuts 
was continued through the margin, and the latter was then 
spread out into a linear form by gently pressing the animal against 
the flat side of the glass vessel in which it was contained. The 
same experiment performed on Aurelia is, of course, attended 
with a totally different result, now one segment and now another 
originating a discharge which then spreads to all the others in 
the form of a contraction-wave. 
