124 THE DISrERSAL OF SHELLS. 



is popularly supposed ; and before having travelled far 

 the " raft " is sure to be lashed by the waves, or melted 

 at the base by warmer water or by the wear and tear 

 of its motion through the sea ; " pieces will calve or 

 break off, and before long the berg will capsize, owing 

 to its being top-heavy, and the whole burden it bears be 

 tumbled into the sea ; " in like manner, it is stated, ice- 

 fields, too, will break in pieces and discharge their loads. 

 Referring more especially to the dispersal of seeds, it is 

 also remarked that '^ the only possible chance a seed 

 carried by ice has to germinate in a new situation is 

 when the ice grounds on a low islet, or is dashed on a 

 lee shore by the action of the winds — an event which 

 rarely happens. Even when stranded on a low shore 

 it cannot approach near enough for its burden to be 

 thrown on land, as a low-lying coast has shallow water 

 off it ; or if deep off shore the cliffs are in general high, 

 so that this amounts to the same thing." Seeds or 

 fruits, it might be remarked, when ultimately washed 

 upon the strand by the waves, might be picked up and 

 carried inland by birds, for some are well known to pass 

 the intestines unhurt ; but shells, similarly washed up in 

 a living state, if swallowed by birds, would generally 

 be killed and digested. 



Floating pumice-stone, from its porous and sponge- 

 like texture, Mr. Bates and Sir C. Lyell have pointed 

 out, seems likely to be a vehicle for the transport of the 

 eggs of various animals, both terrestrial and aquatic. 

 According to Mr. Bates, pieces have been seen 

 floating on the surface of the main current of the 



