Leeches should be applied where the patient would be found to be old or imbecile, or a woman, or an infant, or a person of an extremely timid disposition, or a person of a delicate constitution, and as such is not fit to be surgically operated upon, since this mode of bleeding is the gentlest that can be possibly devised. The blood vitiated by the deranged wind (Vayu), bile (Pittam), and phlegm (Kapham) should be respectively sucked through a horn, by leeches and a gourd appliance (Alavu-Yantra) or with whichsoever of them is available at the time, irrespective of the cause of such vitiation, whenever such bleeding or sucking would be found to be imperatively necessary.
A cowhorn is described in the Shastras as of a hot or heat making potency, and as possessed of a slightly cooling (Snigdha) or soothing (Madhura) property. Accordingly it should be used in sucking the blood vitiated through the action of the deranged bodily wind. Leeches, which are born in water, are possessed of Madhura (sweet or soothing) properties, and hence they should be used in sucking the blood vitiated through a deranged condition of the bile (Pittam). The gourd (Alavu) is pungent, parching and irritating in its potency and should be therefore used in sucking the blood vitiated through the action of the deranged phlegm (Kapham).
The part from which the blood is to be sucked should be first scarified or slightly cut in two or three places, and then the mouth or the open end, of the horn, covered with a thin piece of muslin tied round its edges should be placed over it and sucked with the mouth through the aperture at its tip or top-end, or with a gourd appliance equipped with a lighted lamp placed in its inside.
The term Jalauka (leeches) may be etymolo-gically interpreted to mean creatures whose life (Ayu) or whose longevity is in, or depends upon, water, whereas the derivative meaning of the term Jalauka (leeches) is based upon the fact of their dwelling ("Oka" - dwelling place) in water (Jalam). Leeches may be divided into twelve distinct species of which six are venomous, and six non-venomous. The six venomous species are named Krishna, Karvura, Alagarda, Indrayudha, Samudrika and Gochandana. The leeches of the first-named species (Krishna) are marked by thick heads, and of a colour resembling powdered lampblack. The leeches of the Karvura type have extended or elongated bodies like the Varmifishes, and are indented and thick at the waist. The Alagarda leeches are hairy, thick and round at the sides, and black at the mouth. The leeches of the Indrayudha species are marked on the surface with up-pointed rainbow coloured lines. The skins of the Samudrikas are blackish yellow, dotted over with white spots of a variety of shapes. Leeches which are provided with narrow mouths and are marked by bifurcating line at the bottom like the scrotal sac of a bull are called Gochandanas.
A person bitten by any of the abovesaid venomous leeches has an irresistble inclination to scratch the seat of the bite which is marked by a considerable swelling. Fever, with burning, retching, drowsiness and delirium supervenes and ultimately the patient loses all consciousness. The remedy consists in the administration of an anti-toxic medicine known as Mahagada, as snuffs, potions and unguents, etc. A bite by an Indrayudha usually proves fatal. Venomous leeches, as well as cures for their bites, have thus been described.
The non-venomous species include Kapilas, Pingalas, Shankhamukhis, Musikas, Pundarimukhis and Saravikas. The Kapilas are coloured like Manah-Shila (realgar) at the sides, and their backs are tinged with a glossy hue like that of a Mudga pulse. The Pingalas have a reddish colour, are round in shape and capable of speedy locomotion. The Shankhamukhis are marked by a blackish red hue like that of the liver, are provided with sharp elongated mouths, and are capable of sucking blood with the greatest swiftness. The Musikas are coloured like the common blind moles, and emit a fetid smell from their bodies. The Pundarimukhas are coloured like the Mudga pulse and are so called from the fact of the resemblance of their mouths to the full-blown lotus lilies (Pundarikas). The Saravikas have cold bodies marked with impressions like lotus leaves and measure eighteen fingers' width in length, and they should be employed in sucking blood from the affected parts of lower animals. This exhausts the list of non-venomous leeches.
The countries, such as Turkesthan (Yavana), the Deccan (Pandya), the tract of land traversed by the Ghaut mountains (Sahya), and Pautana (modern Mathura), are the natural habitats of these leeches. The leeches, found in the aforesaid countries, are specifically non-venomous, strong, large-bodied, greedy and ready suckers.
The venomous leeches have their origin in the decomposed urine and fecal matter of toads and venomous fishes in pools of stagnant and turbid water. The origin of the non-venomous species is ascribed to such decomposed vegetable matter, as the petrified stems of the several aquatic plants known as Padma, Utpalam, Nalina, Kumuda, Pundarika, and the common zoophytes which live in clear waters.
Authoritative verse on the subject. - The non-venomous leeches swim about in sweet scented waters, live on non-poisonous weeds, lie on the leaves of flowering water plants instead of on the dank and oozy beds of pools, and suck blood from the affected part of a human organism without causing any discomfort.
Leeches should be caught hold of with a piece of wet leather, or by some similar article, and then put in to a large-sized new pitcher filled with the water and ooze or slime of a pool. Pulverised zoophytes and powder of dried meat and aquatic bulbs should be thrown into the pitcher for their food, and blades of grass and leaves of water-plants should be put into it for them to lie upon. The water and the edibles should be changed every second or third day, and the pitchers should be changed each week, (the leeches should be transferred to a new pitcher at the end of every consecutive seven days).