WORMS. 271 



produced by a cupping-glass. The skin covered is drawn 

 into the hollow so far as to render it quite tight, by the 

 pressure of the surrounding air. Thus it is brought into 

 contact with the edges of the three jaws, to which, by 

 means of powerful muscles attached to them, a see-saw 

 motion is communicated, which causes the little teeth 

 soon to cut through the skin and superficial vessels, 

 from which the blood begins to flow. The issue of the 

 vital fluid is then promoted by the pressure around, and 

 so goes on until the enormous stomach of the Leech is 

 distended to repletion. 



It has been suggested that this whole contrivance, with 

 the instinct by which it is accompanied, is intended for 

 the benefit of Man, and not of the Leech. Blood seems 

 to be by no means the natural food of the Leech; it has 

 been ascertained to remain in the stomach for a whole 

 twelvemonth without being digested, yet remaining fluid 

 and sound during the entire period : while, ordinarily, 

 such a substance cannot in one instance out of a thousand 

 be swallowed by the animal in a state of nature. 

 Whether this is so or not, — whether man's relief under 

 suffering was the sole object designed, or not, it was 

 certainly one object ; and we may well be thankful to 

 the mercy of God, who has ordained comfort through 

 so strange an instrumentality. 



The progress of marine natural history, as studied in 

 the aquarium, has made our drawing-rooms and halls 

 familiar with a multitude of curious and beautiful creatures 

 which a few years ago were known only, and that very 

 imperfectly, to the learned professors of technical science. 

 Among the forms which embellish our tanks are several 

 species of Serpula, and Worms allied to it. The shelly 

 contorted tube which this painted Sea-worm inhabits, and 

 which it has built up around its own body, with stone 

 and cement which that body supplied, is well known to 

 you ; as is also the curious conical stopper with which it 



