62 THE CABLE OF THE PINNA. 



exude in a glutinous state from a particular organ at 

 the base of the foot. They are not spun out by being 

 drawn from the secreting apparatus, but are modelled, 

 so to speak, by the foot itself. The structure and the 

 process here apparent are alike remarkable : from the 

 root of the foot to its extremity runs a long groove, 

 the sides of which are so constructed as to fold over, 

 and thus complete a minute canal. Along this canal, 

 as a mould, the glutinous matter runs, soon acquiring 

 consistence, and appearing as a thread. When this 

 thread is sufficiently tenacious, the animal protrudes 

 its foot, and with its extremity attaches the end of the 

 thread to the substance on which it is to be fixed. 

 This being done, the pinna now expands its foot, open- 

 ing" the canal so as to free the thread from its in- 

 closure. The foot is then withdrawn, new matter is 

 poured along the groove, and thus the operation is 

 repeated till the cable is secure. Is not here a claim 

 on our high admiration? It is said that the pinna is 

 only capable of producing four or five threads in the 

 course of twenty-four hours, the production and hard- 

 ening of the glutinous fluid being a tedious process. 

 Security against storms and rolling waves is evidently 

 the design aimed at, both in the immediate union of 

 shells to the rock, and in their anchorage by means 



