Peltier's observations on annelids. 67 



point where the fluid, having been already absorbed, 

 ceases to arrive. Here we see in the middle of the body, 

 at the very point where the nutritive fluid is arrested, a 

 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 fm^- 

 nished by the anterior half. As soon as these vesicles 

 begin to act, the posterior half of the dorsal vessel re- 

 assumes its contractile movements. These contractions 

 have their origin 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 con- 

 striction 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 re- 

 peated, and this again may be repeated, so that six dis- 

 tinct 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 maintain starvation to be a cause of over-popula- 

 tion ! Quatrefages has noticed an analogous case in 

 the Synapta. " Hunger is the sole cause of the spon- 

 taneous amputations," he says. " It would incline one 

 to say that the animal, feeling himself 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 

 questions relating to the Annelids — Dr Thomas Williams 



* Quatrefages, Souvenirs dj'iin Naturaliste, i. 62. 



