170 jELLY-nsn, star-fish, and sea-urchins. 



irregular intervals, a contraction so feeble that it 

 was restricted to the immediate vicinity of the 

 lithocyst in which it originated. Soon after this 

 stage irritability towards all kinds of stimuli entirely 

 ceased, including even strong spirit dropped on the 

 under surface of the animal when taken momentarily 

 out of the water. All these stages thus described 

 were passed through rapidly, the whole series occu- 

 pying rather less than five minutes. On now leav- 

 ing the specimen for ten minutes and then restoring 

 it to its original water at 45°, all the above-men- 

 tioned stages were passed through in reverse order. 

 The first faint marginal contraction was confined to 

 the immediate vicinity of the prepotent lithocyst, 

 and all subsequent contractions continued to be so 

 for the next three minutes. Rhythm very slow. 

 Contractions now began to penetrate round the 

 margin, and in eight minutes from the restoration 

 had gone all the way round, the rate of their 

 rhythm meanwhile increasing. In two minutes 

 more all the umbrella was contracting at the rate 

 of fifteen per minute. 



In another specimen, subjected to the same con- 

 ditions, the rate of recovery was even more rapid, 

 occupying only two minutes altogether ; but in 

 every case the process of recovery is a gradual one, 

 and differs only in the time it occupies in passing 

 through the various stages. 



Effects of Freezing Meduscs. 



In conclusion, I will describe some rather interest- 

 ing experiments that consisted in freezing some 



