198 JELLY-FISH, STAR-FISH, AND SEA-URCHINS. 
swimming movements in response to natural or 
ganglionic stimulation. And, as already observed, 
this peculiarity of the excitable tissues is also well 
marked in the case of the artificial stimulation of 
deganglionated specimens under otherwise similar 
conditions. 
One further experiment may here be mentioned. 
Having split open the paralyzed bell of Sarsia along 
the whole of one side from base to apex of the cone, 
I suspended the now sheet-like mass of tissue by 
one corner in the air, leaving the rest of the sheet 
to hang vertically downwards. By means of a 
rack-work support I now lowered the sheet of tissue, 
till one portion of it dipped into a beaker filled 
with a solution of glycerine of appropriate strength. 
After allowing this portion to soak in the solution 
of glycerine until it became slightly opalescent, I 
dropped the entire mutilated bell, or sheet of tissue, 
into another beaker containing sea-water. If the 
exposure to the glycerine solution had been of 
sufficient duration, I invariably found that in the 
normal sea-water the rhythmic movements were 
performed by the whole tissue-mass quite as 
efficiently as was the case in my other experiments, 
where the whole tissue-mass, and not merely a por- 
tion, had been submitted to the influence of the 
irritant. But on now suddenly snipping off the 
opalescent portion of the tissue-mass, 2.e. the por- 
tion which had been previously alone submitted to 
the influence of the irritant, all movement in the 
remainder of the tissue-mass instantly ceased. This 
experiment I performed repeatedly, sometimes ex- 
