CO-ORDINATION. 133 
I have endeavoured to settle this question, I wiil 
not here occupy space in detailing them. 
It seems desirable, however, in this connection 
again to mention a fact briefly stated in a former 
chapter, namely, that section conclusively proves 
a contraction-wave to have the power, when it 
reaches a lithocyst, of stimulating the latter into 
activity ; for it is not difficult to obtain a series 
of lithocysts connected in such a manner that the 
resistance offered to the passage of the waves by 
a certain width of the junction-tissue, is such as 
just to allow the residuum of the contraction-wave 
which emanates from one lithocyst to reach the 
adjacent lithocyst, thus causing it to originate 
another wave, which, in turn, is just able to pass to 
the next lithocyst in the series, and so on, each 
lithocyst in turn acting like a reinforcing battery 
to the passage of the contraction-wave. Now this 
fact, I think, sufficiently explains the mechanism of 
ganglionic action in those cases where one or more 
lithocysts are prepotent over the others ; that is to 
say, the prepotent lithocyst first originates a con- 
traction-wave, which is then successively reinforced 
by all the other lithocysts during its passage round 
the swimming-bell. In this way the passage of 
a contraction-wave is no doubt somewhat accele- 
rated; for I found, in marginal strips, that the rate 
of transit from a terminal lithocyst to the other 
end of the strip was somewhat lowered by excising 
the seven intermediate lithocysts. 
I may here state, in passing, a point of some 
little interest in connection with this reinforcing 
T 
