CO-ORDINATION. 137 



the natural rhythm) which passed from B to A, one 

 would pass from A to B.* 



Of course the only interpretation to be put on 

 these facts is that every time an artificially started 

 wave reached the terminal ganglion it caused tlie 

 latter to discharge; but that the occurrence of a 

 discharge could not in this case be rendered ap- 

 parent, because of the inadequacy of that discharge 

 to start a reflex wave. But that such discharges 

 always took place was manifest, both d priori be- 

 cause from analogy we may be sure that if there 

 had happened to be any contractile tissue of appro- 

 priate width on the other side of the ganglion, the 

 discharge of the latter would have been rendered 

 apparent, and d posteriori because, after the arrival 

 of every artificially started wave, the time required 

 for the ganglion to originate another wave was pre- 

 cisely the same as if it had itself originated the 

 previous wave. 



In view of these results, it occurred to me as an 

 interesting experiment to try the effect on the 

 natural rhythm of exhausting a ganglion thus situ- 

 ated, by throwing in a great number of shocks at 

 the other end of the strip. I found that after five 

 hundred single shocks had been thrown in with a 

 rapidity almost sufiicient to tetanize the strip, im- 

 mediately after the stimulation ceased, the natural 



* When two such waves met, they neutralized each other at 

 their line of collision ; or perhaps more correctly, the tissue on 

 each side of that line, having just been in contraction, was not 

 able again to convey a contraction- wave passing in the oppo- 

 site direction to the wave which it had conveyed immediately 

 before. 



