G4 SEA-SIDE STUDIES. 



constriction of the dorsal vessel, and two large absorbing 

 vesicles are formed, which collect, for the benefit of the 

 posterior half of the animal, the aliment no longer furnished 

 by the anterior half. As soon as these vesicles begin to 

 act, the posterior half of the dorsal vessel reassumes its con- 

 tractile movements. Tliese contractions have their orioin 

 in the vesicles, and have no connection with the anterior 

 half, nor are they synchronous in their movements with it. 

 In front of these vesicles a constriction takes place which 

 finishes by separating the two portions into two distinct 

 animals. If one of these be kept alive in the same drop of 

 water for some days, the aliment gradually diminishing, the 

 process is repeated, and this again may be repeated, so that 

 six distinct individuals are produced from one, solely by the 

 deficiency of food, which causes a constriction of the dorsal 

 vessel." What an argument in favour of those who main- 

 tain starvation to be a cause of over-population ! Quatre- 

 fages has noticed an analogous case in the Synapta. "Hun- 

 ger is the sole cause of the spontaneous amputations," he 

 says. " It would incline one to say that the animal, feeling 

 liimself unable to find food for his whole body, successively 

 suppresses those parts which cost too much."* 



It is right to add, that a very great authority on all ques- 

 tions relating to the Annelids — Dr Thomas Williams of 

 Swansea — emphatically denies the whole of the "fables "ori- 

 ginated by Bonnet, and accepted by all successors. He saysf 



* QUATREFAOES, Souvenirs (Tun Xaturallste, i. 62. 



t Williams— 7?<!7Jort on British Annelida, 1851— In Reports of Britieli 

 Association, 1852, p. 247. 



