500 SEA- ANEMONE; ITS REPRODUCTIVE POWERS. 



extremity of the tentacula, and the distension exists in the 

 radiating chambers and arms rath :r than in the stomach. The 

 water is afterwards expelled in jets through the same orifices 

 with considerable force ; so as to rise to the height of a foot or 

 more. There is reason to believe that this process is chiefly one 

 of respiration. The whole interior of the chambers, into which 

 the water is received, is covered with vibratile cilia ; and it has 

 been observed that, if Actiniae are kept in a limited quantity of 

 water, from which the air is soon exhausted, the distension 

 of the body is enormously increased, so that its appearance 

 almost resembles that of an inflated bladder. Sometimes 

 this distending process appears to be performed for the purpose 

 of facilitating locomotion. The animal is then almost of the 

 same specific gravity with water ; and, if it withdraws its foot 

 from its attachment, it is carried away by the least agitation of 

 the water, and may thus go in search of a new abode without 

 exertion of its own. When it is cast upon a surface adapted to 

 its wants, it forms a new attachment ; and there remains, until 

 deficiency of food or some other cause again excites it to removal. 

 It would appear that, when thus supported by the water, it can 

 use its tentacula for assisting in its movements ; and can even 

 walk upon these, turning its mouth downwards. It can, how- 

 ever, glide along the surface of a rock, by the alternate contrac- 

 tion and expansion of the fleshy foot in one particular direction, 

 in just the same manner that the Snail, or other Gasteropod 

 Mollusca, perform their movements. 



1068. The power enjoyed by the Actinia of reproducing 

 parts of which it has been deprived, is almost equal to that pos- 

 sessed by the Hydra ( 1050). Our knowledge of it is principally 

 due to the experiments of Dicquemare. He found, that if the 

 tentacula be cut off, they are soon replaced. If the body be 

 divided transversely, so that the upper portion possesses a 

 mouth and tentacula but no base, and the lower one has the 

 base and open stomach without a regular mouth or tentacula, 

 both parts will continue to live, the one gradually closing its 

 under side,* and forming a new disk, the other after some 



* This is not always the case, however. In cue instance, a new set of tentuculu 

 were sent forth, and a complete new mouth formed, at the lower orifice ; so that 

 the animal could take food by either. 



