86 SEA-SIDE STUDIES. 



the water destroys this milt, and consequently prevents the 

 fecundation of the eggs, nipping the young molluscs in the 

 bud. By thus becoming a zoological Herod, and destroyino- 

 the innocents wholesale, in a few seasons you may clear the 

 docks of every individual Teredo, and your ships will be 

 safe." 



I see by the intelligent twinkle of his eye that he has 

 seized this notion with decisive approbation, and from this 

 moment begins to think there may be some use, after all, 

 in Natural History. I almost feel tempted to show him my 

 Pholas, although it is not a very interesting animal to watch. 

 There is a somnolent lethargy, an otiosity of do-nothingism 

 in its demeanour, surprising in one who bores through rocks 

 as we tunnel the Jura. He will not even bore now. I have 

 tried him in vain. He lolls his gi-eat length at the bottom 

 of the pan, and declines the lump of wood placed before him. 

 In fact, he does nothing l)ut suck in the water at one tube 

 of his siphon, and squirt it out of the other. Do observe 

 that siphon or double tube, like a double-barrelled gun, the 

 lining membrane of which is covered with vibratile cilia. 

 Tlie incessant action of these cilia draws the water in at the 

 orifice of the upper and larger tube, along which it passes 

 and reaches the gills, where the blood is aerated ; and then 

 the water makes its exit from the under tube, in a steady 

 current, visible to the naked eye. How this is performed is 

 to me a my.stery, for my dissections wholly foiled in tracing 

 a7iy direct communication between the two tubes ; but that 

 there must be some intlirect communication is certain, since 

 the evidence of the two cui-rents, one of entrance, and one of 



