ARTIFICIAL RHYTHM. 185 



of critics, viz. that if, as current views respecting 

 the theory of rhythm would suppose, it is ex- 

 clusively the ganglionic element which in the 

 unmutilated Aurelia causes the rhythm of the 

 swimming motions by intermittent stimulation, 

 surely it becomes a most unexpected and unaccount- 

 able fact, that after the removal of this element the 

 contractile tissues should still persist in their 

 display of rhythm under the influence of constant 

 stimulation. At any rate no one, I think, will 

 dispute that the facts which I have adduced justify 

 us in reconsidering the whole theory of ihythm as 

 due to ganglia. 



As I have already said, I am not inclined to 

 deny that there is probably some truth in the 

 current theory of rhythm as due to ganglia; 1 

 merely wish to point out distinctly that this theory 

 is inadequate, and that in order to cover all the 

 facts it will require to be supplemented by the 

 theory which I now propose. The current theory 

 of rhythm as due to ganglia attributes the whole 

 of the effect to the ganglionic element, and thus 

 fails to meet the fact of a rhythm which is artifi- 

 cially produced after the ganglionic element has 

 been removed. It also fails to meet a number of 

 other facts of the first importance ; for it is be- 

 yond all doubt that rhythmic action of the strictest 

 kind occurs in an innumerable multitude of cases 

 where it is quite impossible to suppose anything 

 resembling ganglia to be present. Not to mention 

 such cases as the Snail's heart, where the most 

 careful scrutiny has failed to detect the least ves- 



