200 ZOOPHYTES. 



the crassicornis is often covered by sand or the fragments of shells: the 

 tentacula constantly retain every thing coming in contact with them. 

 But this adhesion is the exercise of a peculiar faculty : it is optional ; sub- 

 stances are allowed to pass over or to fall from the tentacula at will : nor 

 is it obvious how adhesion, either there or to the rest of the body, or of 

 the base itself, is effected. 



Excessive turgidity or intumescence is derived principally, if not ex- 

 clusively, from the quantity of water absorbed, besides the animal's gorg- 

 ing itself with food. Evacuation of the water is followed by contraction. 

 Sometimes what are apparently fine and ample specimens, discharging the 

 water, prove incapable of replenishing themselves. They diminish to 

 small dimensions and perish. This evacuation is occasionally attended by 

 eversion of the stomach. A very large specimen of the crassicornis has 

 distended itself to unusual size, so that the skin seemed comparatively 

 thin. Eversion of the stomach, evacuation and contraction of the ten- 

 tacula followed, the animal quickly died. The like has been witnessed of 

 the Dianihus or Plumosa. It is by water alone that the tentacula are 

 distended. Nothing is so grateful to the animal, so salubrious and 

 invigorating, as frequent and abundant supplies of this element. It is in- 

 finitely enfeebled, and indeed the adhesive power is lost, by remaining in 

 wbat is unchanged for months. But, although pining to a tenth of its 

 natural size, and remaining pertinaciously contracted by neglect, it speedily 

 expands after the longest intervals, to enjoy that which comes recent from 

 the sea, and gradually recovers its pristine vigour and beauty. 



If the water is renovated every fourth or fifth day, it will be found 

 sufficient. 



The size and appearance of the Actinia may be therefore considered 

 as absolutely dependent on the renovated element, on sustenance and 

 heat. In common with most of the soft-bodied animals, it contracts 

 during cold weather, and expands under a genial temperature. Farther 

 than this, there is no reason to admit its susceptibility of atmospherical or 

 meteorological influence, far less that it prognosticates what shall ensue. 



The remarkable distension adverted to above, without any obvious 

 cause, is generally an unfavourable symptom, and very ready to delude 



