ARTIFICIAL RHYTHM, 185 
of critics, viz. that if, as current views respecting 
the theory of rhythm wouid 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 tissees 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 rhythm 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; | 
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- 
