180 SEA-SIDE STUDIES. 



wliite dianiJius in the Vivarium of a friend at Leith, 

 and was told that the Actinia, while moving round 

 the tank, had left behind it small white bodies, which 

 separated themselves from the foot or sucker and be- 

 came young Actinias. Sir John Dalyell had described 

 a similar mode of multiplication in Actinia lacerata, 

 and HoUard in Actinia rosea (?) The former writer 

 had observed that Actinia lacerata protruded from 

 all parts of its foot, stolons or suckers, which became 

 detached, and presently put forth tentacles, and were 

 developed into minute Actinias. After reading Sir 

 John Dalyell's account of Actinia lacerata, Dr Wright 

 was anxious to ascertain whether there might not be 

 included in the prolongations separated from the foot, 

 either true ova or germs, or some tissue specialised for 

 the production of young. In the hydroid zoophytes, 

 such as Hydra, Goryne, &c., the walls of the body 

 consisted of three elements or layers, — a dermal or in- 

 tegumental, an areolar or muscular, and a mucous or 

 intestmal layer ; and when gemmation took place in 

 these animals, it occurred by the protrusion of a simple 

 diverticulum or sac from the canal of the body, formed 

 of all the three elements. This diverticulum was de- 

 veloped into a polype body, with mouth and tentacles 

 like those of the polype, from which it pullulated ; the 

 two bodies having the digestive canal and all the tissues 

 continuous with each other. In Hydra tuba multipli- 

 cation took place by stolons, which extended to some 

 distance from the body before the new polype bodies 

 sprouted from them ; but in that case also a prolonga- 



