POISONS. 251 



quent, till at last they altogether die away. Irrita- 

 bility, however, still continues for a time — a nip 

 with the forceps being followed by a bout of rhyth- 

 mical contractions. Death occurs in several hours 

 in strong and irregular systole. 



" If the exposure to sea- water has only lasted two 

 minutes, a similar series of phenomena is presented, 

 except that the s})ontaneous twitching movements 

 supervene in much less time than twenty minutes. 

 But an exposure of one minute may determine a 

 fatal result a few hours after the Medusa has been 

 restored to fresh water. 



"Contact with sea- water causes an opalescence 

 and eventual disintegration of the tissues, which 

 precisely resemble the effects of fresh water upon 

 the marine Medus^^. When immersed in sea-water 

 this Medusa floats upon the surface, owing to its 

 smaller specific gravity. 



" In diluted sea-water (fifty per cent.) the pre- 

 liminary tonic spasms do not occur, but all the 

 other phases are the same, though extended through 

 a longer period. In sea- water still more diluted 

 (I in 4 or 6) there is a gradual loss of spontaneity, 

 till all movement ceases, shortly after which irri- 

 tability also disappears ; manubrium and tentacles 

 expanded. After an hour's continued exposure, 

 intense rigor mortis slowly and progressively de- 

 velopes itself, so that at last the bell lias shrivelled 

 almost to nothing. An exposure of a few minutes 

 to this strength [)laces the animal past recovery 

 when restored to fresh water. In still weaker mix- 

 tures (1 in 8, or 1 in 10) spontaneity persists for a 



