CO-OllDINATION. 138 



I have endeavoured to settle this question, I will 

 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, wdiich, 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 

 10 



