66 SEA-SIDE STUDIES. 



dition of " hanging to its mother's tail," which I have 

 heard applied in metaphorical sarcasm to small boys 

 anxious to be with their mothers. The young one 

 only hved four days. 



This spontaneous self-division of worms is a curi- 

 ous fact, first observed and accurately described by the 

 Genevese naturalist, Charles Bonnet,* whose discoveries 

 in reproduction we shall have to consider in a sub- 

 sequent chapter. He found the fresh-water Nais 

 frequently double, and saw the separation take place. 

 He also cut the worm into several pieces, and observed 

 each piece reproduce its head, and gTow into a perfect 

 worm. One observation he made is worth repeating 

 here.-|- He cut a Nais transversely, but not entirely 

 in two ; that is to say, the two portions were held 

 together by a mere thread ; in less than an hour after- 

 wards the two were again perfectly united, and no 

 trace remained of the operation, except a slight con- 

 striction, and an interruption in the continuity of the 

 vessels and viscera. This interruption was very similar 

 to such as he had observed in several worms in their 

 ordinary condition ; and if we compare the observation 

 with that made by M. Peltier, j we shall see that they 

 confirm each other. " In those species,'' says M. 

 Peltier, " which have a dorsal contractile vessel, in 

 which the course of the nutritive fluid can be traced, 

 we see that in proportion as the fluid becomes poorer, 

 the contraction becomes feebler, and is arrested at the 



* Bonnet : Traite iV Insectologie, 1745, vol. ii. f Ibid. ii. 133. 



X See Conqjfes Henchis des Seances deV Academie, 1844, Jan. 22. p. 161. 



