STRUCTURE OF WORMS. 81 



earth-worm, inhabit the water. Many of them bury them- 

 selves in the sand ; others form themselves a sort of tube or 

 habitation of sand, bits of dirt, gravel, or other materials ; 

 and others exude from their surfaces a calcareous matter, 

 which produces a shell around them. 



Among the animals belonging to this class are the earth- 

 worm, the leech, and the hair-worm. 



The appearance of Earth-worms is familiar to all. They 

 attain sometimes to the length of a foot^ and have as many as 

 a hundred and twenty rings, each of which is furnished with 

 the little bristles or spines above mentioned. They emit 

 through certain pores a slimy fluid, which lubricates their 

 bodies, and thus gives them an easier passage through the earth, 

 which they traverse in every direction. They feed upon roots, 

 woody fibres, and the remains of animal and vegetable mat- 

 ter. They swallow earth also in considerable quantity, but 

 this is probably on account of the animal or vegetable matter, 

 in a state of decomposition, which it may contain. When 

 cut through the middle, each portion becomes a distinct 

 individual. And in some worms nearly resembling the earth- 

 worm, but residing in the water, the power of reproduction is 

 nearly equal to that of the polypes. 



The Leech has three jaws, or rather lancets, with which it 

 pierces the skin of animals, in order to suck their blood. 

 Its tail is furnished with a shallow cup or disk, by which it is 

 able to fix itself firmly to different objects, while obtaining 

 its nourishment in this manner ; and by means of the same 

 organ, it moves from place to place. There are several spe- 

 cies of the leech, of which the medicinal leech is the most 

 valuable, from the use made of it in local blood-letting. 

 The horse-leech has the same power of drawing blood, but 

 the wounds which it makes are sometimes poisoned, and fol- 

 lowed by bad effects. 



The body of the Gordius, or Hair-worm, is long, shaped 

 like a thread or hair, nearly smooth and round. It is a vulgar 

 notion that the hair of the human head, or of a horse's tail, if 

 thrown into the water, acquires life, and is converted into a 

 worm. A species of the hair-worm, in Africa and the Indies, 

 is extremely noxious. It is of a pale, yellowish color, and is 

 frequently met with among the grass, especially when covered 

 with dew. It often insinuates itself into the naked feet or limbs 

 of children and unwary persons, where it produces an inflam- 

 mation that is sometimes fatal. Great care and attention are 

 itquired in extracting it; for if it be broken during the ope- 



