CO-ORDINATION. 131 
parts of the swimming-bell seem to contract at the 
same instant. And this apparently perfect co- 
ordination among the eight marginal ganglia may 
continue for any length of time. I believe, however, 
that such apparently complete physiological har- 
mony is not co-ordination properly so called, 1.e. is 
not due to special nervous connections between the 
ganglia; for, if such were the case, perfectly syn- 
chronous action of this kind ought to be the rule 
rather than the exception. 
I am therefore inclined to account for these cases 
of perfectly synchronous action by supposing that 
all, or most, of the ganglia require exactly the same 
time for their nutrition ; that they are, further, of 
exactly equal potency in relation to the resistance 
(or excitability) of the surrounding contractile 
tissues ; and that, therefore, the balance of forces 
being exactly equal in the case of all, or most, of the 
ganglia, their rhythm, though perfectly identical, is 
really independent. I confess, however, that I am 
by no means certain regarding the accuracy of this 
conclusion, as it is founded on negative rather than 
on positive considerations: that is to say, I arrive 
at this conclusion regarding the cases in which such 
apparent co-ordination is observable only because 
in other cases such apparent co-ordination is not 
observable; and also, I may add, because my 
experiments in section have not revealed any 
evidence of nervous connections capable of con- 
ducting a stimulus-wave with greater rapidity than 
a contraction-wave. I therefore consider this con- 
clusion an uncertain one, and its uncertainty 15, 
