144 JELLY-FISK, STAR-FISH, AND SEA-URCHINS. 



of SarsitC, by submitting the animals to severe 

 nervous sliock. 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 invariabl}^ 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 o£ producing 

 nervous shock, and this I found a more effectual 

 method than the one just described. It consisted 

 in violently shaking the Sarsise 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 SarsitB 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- 



