THE LEECH KIND. 



763 



perfectly harmless ; baring been often hand- 

 led and irritated, without any vindictive con- 

 sequences. 



All these, as well as the scorpion, are sup- 

 posed to be produced perfect from the pa- 

 rent, or the egg; and to undergo no changes, 

 after their first exclusion. They are seen of 



all sizes ; and this is a sufficient inducement 

 to suppose, that they preserve their first ap- 

 pearance through the whole of their exist- 

 ence. It is probable, however, that like 

 most of this class, they often change their 

 skins ; but of this we have no certain infor- 

 mation. 



CHAPTER CLXXV1I. 



OF THE LEECH. 



THE last of this wingless tribe that I shall 

 mention is the Leech, which, like all the for- 

 mer, undergoes no varieties of transformation; 

 but when once excluded from the body of 

 the parent, preserves its first figure to the end. 

 I place the history of the leech among the 

 first class of animals; while I have degraded 

 the Earth-worm, the Tasnia, and the Polypus, 

 into the class of Zoophytes, or that imperfect 

 tribe which serves to make the shade be- 

 tween animal and vegetable nature. Not 

 but that the earth-worm or the polypus have 

 their motions, their appetites, and their vital 

 principles, as complete as the leech, and, to 

 a cursory view, appear every way as com- 

 plete animals. But there is one circumstance 

 that lays the line between them ; that exalts 

 the one and degrades the other. The earth- 

 worm a;id the polypus may be cut in two 

 pieces, and each piece will produce a new 

 and perfect animal : the leech cannot suffer 

 this dissection, but dies when cut in t\vo; an 

 evident instance that it is possessed of a more 

 perfect organization than those animals which 

 it otherwise very much resembles. 



The leech, from its uses in medicine, is one 

 of those insects that man has taken care to 

 provide; but of a great variety, one kind 

 only is considered as serviceable. The 

 horse-leech, which is the largest of all, and 

 grows to four inches in length, with a glossy. 

 black surface, is of no use, as it will not stick 

 to the skin; the snail-leech is but an inch in 

 length ; and though it will stick, is not large 

 enough to extract a sufficient quantity of 

 blood from the patient; the broad-tailed 



NO. 63 66. 



leech, which grows to an inch and a half in 

 length, with the back raised into a sort of 

 ridge, will stick but on very few occasions: 

 it is the large brown leech, with a whitish 

 belly, that is made use of in medicine, and 

 whose history best merits our curiosity. 



The leech has the general figure of a worm, 

 and is about as long as one's middle finger. 

 Its skin is composed of rings, by means of 

 which it is possessed of its agility, and swims 

 in water. It contracts itself, when out of 

 water, in such a manner, that when touched 

 it is not above an inch long. It has a small 

 head, and a black skin, edged with a yellow 

 line on each side, with some yellowish spots 

 on the back. The belly ateo, which is of a 

 reddish colour, is marked with whitish yellow 

 spots. But the most remarkable part of this 

 animal is the mouth, which is composed of 

 two lips, that take whatever form the insect 

 finds convenient. When at rest, the opening 

 is usually triangular; and within it are placed 

 three very sharp teeth, capable of piercing 

 not only the human skin, but also that of a 

 horse or an ox. Still deeper in the head, is 

 discovered the tongue, which is composed of 

 a strong fleshy substance, and which serves 

 to assist the animal in sucking, when it has 

 inflicted its triple wound; for no sooner is 

 this voracious creature applied to the skin, 

 than it buries ifs teeth therein, then closes 

 its lips round the wound which it has made; 

 and thus, in the manner of a cupping-glass, 

 extracts the blood as it flows to the different 

 orifices. 



In examining this animal's form farther to- 

 5O 



