144 JELLY-FISH, STAR-FISH, AND SEA-URCHINS. 
of Sarsiz, by submitting the animals to severe 
nervous shock. The method I employed to pro- 
duce the nervous shock, without causing mutilation, 
was to take the animal out of the water for a few 
seconds while I laid it on a small anvil, which I 
then struck violently with a hammer. On imme- 
diately afterwards restoring the Medusa to sea- 
water, spontaneity was found to have ceased, while 
irritability remained. After a time spontaneity 
began to return, and its first stages were marked 
by a complete want of co-ordination ; soon, however, 
co-ordination was again restored. But this experi- 
ment by no means invariably yielded the same 
result. Spontaneity, indeed, was invariably sus- 
pended for a time; but its first return was not 
invariably, or even generally, marked by an absence 
of co-ordination, even though I had previously struck 
the anvil a number of times in succession. I was 
therefore led to try another method of producing 
nervous shock, and this I found a more effectual 
method than the one just described. It consisted 
in violently shaking the Sarsiz in a bottle half filled 
with sea-water. I was surprised to find how 
violent and prolonged such shaking might be with- 
out any part of the apparently friable organism, 
except perhaps the tentacles and manubrium, being 
broken or torn. The subsequent effects of shock 
were remarkable. For some little time after their 
restoration to the bell-jar, the Sarsize had lost, not 
only their spontaneity, but also their irritability, 
for they would not respond even to the strongest 
stimulation. In the course of a few minutes, how- 
