LEECH

This name is given to those abranchiate red-blooded worms, or anelli dans, which are provided with a sucker at both ends of the hoA\{see HiRUDo),and of which we po e a few native species; some frequenting the fresh waters, as the horse leeches (Htemopis san gui sorb a and H.stagnorum); others the ocean, where they are parasitic upon fishes, as the skate-sucker (Pontobdella muricata). The medicinal leech (Sanguisu^a medicinal is) belongs to that subdivision of the family Hirudinidte which is characterized by having the superior lip of the anterior cup or sucker divided into several segm'ents, and the oral aperture transverse, triradiate, and surrounded by three cartilaginous jaws, each armed with two rows of very fine teeth. This apparatus enables the leech to penetrate the skin so as to ensure a ready flow without causing a dangerous wound. The upper lip is marked with ten small points considered as eyes. The species of the genus San^uisuf;a, viz. S. officinal is and S. medicinal is, are most common m the south of France, whence great numbers are exported to this country. The leech-dealers of Bretagne drive horses and cows into the ponds, that the leeches may fatten and propagate more abundantly by sucking their blood. Children are employed to catch them by the hand; and the grown persons wade into the shallow waters in the spring of the year, and catch the In eches that adhere to their naked legs. They are also taken by a sort of net made of twigs and rushes, which G50 LEGACY. is used in the summer when the leeches retire into tha deeper waters. The best method of preserving these valuable little animals is stated by the author of the article "Leech " in the Penny Cyclopaedia to be that described by Fee. It is as follows: — Into a marble or stone trough a layer of seven inches of a mixture of mo , turf, and charcoal is to be put, and some small pebbles placed above it; at one extremity of the trough, and midv.ay between the bottom and the top, place a thin plate of marble pierced with numerous small holes, upon which there should rest a stratum of mo , or portions of the; Equisetum palustre, or horse-tail, firmly compre ed by a layer of pebbles. The trougb to be filled with water only so high that the mo and pebbles should be but slightly moistened. A cloth is to be kept over the mouth of the trough. This is imitating as nearly as po ible their natural condition; and the charcoal not only aids in keeping the water sweet, but appears to prevent the leeches being attacked by parasitic animals, to which they are very liable. The water should be changed about once a week, and more frequently in warm weather. The great importance of ascertaining the best method of preserving the medicinal leech may be inferred from the extent to which the trade is carried on, and the consequent increasing scarcity of these indispensable adjuncts to medicine. Four only of the principal dealers in London import 7,200,000 annually. [s. 663]