COMPENDIUM. 283 



with precipitation, and they lurk in concealment, until continued tran- 

 quility, renewing their confidence in security, they return to the enjoy- 

 ments they had left. 



The sensations of the ascidian zoophytes are infinitely keener, and 

 their activity greater, than what is betrayed by any of the rest. 



All the demonstrations and motions of the asteroids have appeared to 

 me much feebler and slower. 



The precise reciprocal relation of the hydrae of the compound zoo- 

 phytes of the same specimen to each other, or the precise relation of any 

 one to the whole community, involves an intricate question. A common 

 benefit seems to be imparted to all, and all seem to be affected by common 

 circumstances. This is viewing the product as a whole. Besides, in a 

 specimen composed of an hundred or a thousand living beings, each of 

 the individuals is so constituted as to receive the benefit adapted for the 

 vital functions peculiar to itself. It seems to originate, to live, and to die, 

 without affecting its nearest neighbour, or of impairing the safety of the 

 community. Herein it appears to be an independent animal, and scarcely 

 more than a solitary individual. 



Notwithstanding, the whole inhabitants of the most luxuriant Sertu- 

 laria, Flustra, or Tubularia, may testify their susceptibility, in as far as we 

 can determine, of the same external impressions, the agency of a single 

 hydra, or of several, neither has any evident influence on the rest, nor, 

 vice versa, is the single hydra, or a group, affected by the rest. 



In some genera, however, comprehending the Coryna, the Vorticella, 

 or the Cristatella, it is difficult to understand how certain positions or in- 

 flections could be assumed without the common will of several parts of the 

 specimen adopting them. The flexure of the Coryna, the collapse of the 

 Vorticella, the progression of the Cristatella, tardy as it is, infinitely sur- 

 passes the power residing in single portions of the product : therefore, they 

 can result only from some general combination of many, or from some 

 occult quality. 



Something like volition is displayed. 



Yet this is a mysterious subject, whereon many profound specula- 

 tions may be indulged to little purpose. 



