212 JELLY-FISH, STAR-FISH, AND SEA-URCHINS. 
of response, and I see no essential difference between 
the rhythmic motions of the simplest organism and 
those of a deganglionated Medusa in acidulated 
water. Lastly, the facts relating to the tonus of the 
manubrium in Sarsia furnish very striking, and I 
think almost conclusive, proof of the theory which 
I have advanced. 
