50 FEBRUAEY. 



said to reside in a very strong glue, a very viscid secre- 

 tion, deposited at the will of the animal " If, having 

 detached a Patella',' says Dr. Johnston, ' the finger be 

 applied to the foot of the animal, or to the spot on 

 which it rested, the finger will be held there by a very 

 sensible resistance, although no glue is perceptible. 

 And it is remarkable that if the spot be now moistened 

 with a little water, or if the base of the animal be cut, 

 and the water contained in it allowed to flow over the 

 spot, no further adhesion will occur on the application 

 of the finger : the glue has been dissolved. It is 

 nature's solvent, by which the animal loosens its own 

 connexion with the rock. When the storm rages, or 

 when an enemy is abroad, it glues itself firmly to its 

 rest; but when the danger has passed, to free itself 

 from this forced constraint, a little water is pressed from 

 the foot, the cement is weakened, and it is at liberty to 

 raise itself and be at large. The fluid of cementation, 

 as well as the watery solvent, is secreted in an infinity 

 of rniliary glands with which the foot is, as it were, 

 shagreened ; and as the Limpet cannot supply the 

 secretion as fast as this can be exhausted, you may 

 destroy the animal's capacity of fixation by detaching 

 it forcibly two or three times in succession." 



If we remove one of these Limpets from his selected 



