The leech used for medical purposes is called the hirudo Medicinalis, to distinguish it from other varieties, such as the horse-leech and the Lisbon leech. It varies from two to four inches in length, and is of a blackish brown colour, marked on the back with six yellow spots, and edged with a yellow line on each side For-tnerly leeches were supplied by Sweden but latterly most of the leeches are procured from France, where they are now becoming scarce.
2230. When leeches are applied to part, it should be thoroughly freed from down or hair by shaving, and all lini-ments, etc, carefully and effectually cleaned away by washing. If the leech is hungry it will soon bite, but sometimes great difficulty is experienced in getting them to fasten on. When this is the case, roll the leech into a little porter, or moisten the surface with a little blood, or milk, or sugar and water. Leeches may be applied by holding them over the part with a piece of linen cloth or by means of an inverted glass, under which they must be placed.
2231. When applied to the gums, care should be taken to use a leech glass, &3 they are apt to creep down the patient's throat; a large swan's quill will answer the purpose of a leech glass. When leeches are gorged they will drop off themselves; never tear them off from a person, but just dip the point of a moistened finger into some salt and touch them with it.
2232. Leeches are supposed to abstract about two drachms of blood, or six leeches draw about an ounce; but this is independent of the bleeding after they have come off, and more blood generally flows then than during the time they are sucking.
2233. After leeches come away, encourage the bleeding by flannels dipped in hot water and wrung out dry, and then apply a warm "spongio-piline" poultice. If the bleeding is not to be encouraged, cover the bites with rag dipped in olive oil, or spread with spermceti ointment, having previously sponged the parts clean.
2234. When bleeding continues from leech bites, and it is desirable to stop it, apply pressure with the fingers over the part, or dip a rag in a strong solution of alum and lay over them, or use the tincture of sesquichloride of iron, or apply a leaf of matico to them, placing the under surface of the lead next to the skin, or touch each bite with a finely-pointed piece of lunar caustic; and if all these tried in succession fail, pass a fine needle through a fold of the skin so as to include the bite, and twist a piece of thread round it. Be sure never to allow any one to go to sleep with leech bites bleeding;, without watching them carefully; and never apply too many to children.
2235. After leeches have been used they should be placed in water, containing" sixteen per cent, of salt, which facilitates the removal of the blood they contain; and they should afterwards be placed one by one in warm water, and the blood forced out by gentle pressure. The leeches should then be thrown into fresh water, which is to be renewed every twenty-four hours; and they may then be re-applied after an interval of eight or ten days; a second time they may be disgorged.
2237. Scarification is useful in severe contusions, and inflammation of parts. It is performed by scratching or slightly cutting through the skin with a lancet, holding the lancet as you would a pen when you are ruling lines on paper.