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 dis- 

 tended 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 twelve- 

 month 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 instru- 

 mentality. 



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 itself 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 



