ARTICULATA— LEECH. 777 



forward the hinder part; in this manner it moves onward, not without great 

 effort ; but the occasions for its progresssive motion are few. 



As it is designed for living under the earth, and leading a life of obscurity, 

 so it seems tolerably adapted to its situation. Its body is armed with small, 

 stiff, sharp burrs or prickles, which it can erect or depress at pleasure ; under 

 the skin there lies a slimy juice, to be ejected as occasion requires at certain 

 perforations, between the rings of the muscles, to lubricate its body, and 

 facilitate its passage into the earth. Like most other insects, it has breath- 

 ing holes along the back, adjoining each ring ; but it is without bones, 

 without eyes, without ears, and, properly, without feet. It has a mouth, 

 and also an alimentary canal, which runs along to the very point of the 

 tail. In some worms, however, particularly such as are found in the bodies 

 of animals, this canal opens towards the middle of the belly, at some dis- 

 tance from the tail. The intestines of the earth worm are always found 

 rilled with a very fine earth, which seems to be the only nourishment these 

 animals are capable of receiving. 



The animal is entirely without brain ; but near the head is placed the 

 heart, which is seen to beat with a very distinct motion, and round it are the 

 spermatic vessels, forming a number of little globules, containing a milky 

 fluid, which have an opening into the belly, not far from the head ; they are 

 also often found to contain a number of eggs, which are laid in the earth, and 

 are hatched in twelve or fourteen days into life, by the genial warmth of 

 their situation. 



When the eggs are laid in the earth, which, in about fourteen days, as has 

 been said, are hatched into maturity, the young ones come forth very small, 

 but perfectly formed, and suffer no change during their existence : how long 

 their life continues is not well known, but it certainly holds for more than 

 two or three seasons. During the winter, they bury themselves deeper in 

 the earth, and seem, in some measure, to share the general torpidity of the 

 insect tribe. In spring, they revive with the rest of nature, and on those 

 occasions a moist or dewy evening brings them forth from their retreats, for 

 the universal purpose of continuing their kind. They chiefly live in a light, 

 rich, and fertile soil, moistened by dews or accidental showers, but avoid 

 those places where th6 water is apt to lie on the surface of the earth, or 

 where the clay is too stiff for their easy progression under ground. 



THE LEECH, 



From its uses in medicine, is one of those insects that man has taken care 

 to propagate t but, of a great variety, one kind only is considered as service- 



98 



