393 
HIR'UDO. 
when food is not to be had, they are able to fupport life 
for many months without receiving any nutriment. This 
is particularly the cafe during winter, at the commence¬ 
ment of which they bury themfelves deep in the mud; 
they continue in a femi-torpid flate, till the warmth of 
the enfuing fpring again calls them to life, vigour, and 
activity. 
Sea-falt, tobacco, and in general all kinds of fait and 
acrid fubfiances, applied to the l'urface of their bodies, are 
fatal to leeches. Some of thefe are always adopted for 
deftroying fuch as fallen upon a man or animal, that hap¬ 
pens unfortunately to go into waters where they are in 
great numbers. When forcibly torn off, they a'lmoft al¬ 
ways leave in the wound fome part of their head. In this 
cafe the wound has often been known to feller and be¬ 
come a troublefome fore. We are informed by Pliny, that 
Meflalinus, a perfon of confular dignity, even loll his life 
by an accident of this kind. 
Leeches ought to be collected in the fpring of the year, 
if poflible, and fnould be kept in velfels of pure fpring 
water, which mull be changed very frequently, particu¬ 
larly in fummer. If they are very numerous, they ought 
to have frelh water as often as twice a-day; but, if they 
are in lmall quantity, once in two days may be fufficient. 
Alt the dime which accumulates upon their bodies fnould 
be well cleaned away whenever they are kept in any 
abundance, otherwife the new water will be tainted, and 
become prejudicial to them from the moment they are 
put into it. Violent noifes and powerful fmells are alike 
injurious to, thefe animals; and, on the latter account 
particularly, an apothecary’s or druggilt’s Ihop is one of 
the worll places in which they can be kept. The perfon 
employed in removing them from one velfel into ano¬ 
ther Ihould have his hands in every refperit as clean as 
poflible. 
There is no great art in applying leeches to the body; 
but a perfon who is accultomed to it will always do it 
better than one who is not. In the moll experienced 
hands, however, they will fometimes refute to fatten them¬ 
felves, either from not being hungry at the time, or from 
the lurface of the (kin, or the blood, on their making the 
attempt, being unpleafant to their tatle. The wound they 
make out of water, is more fenfible than what they make 
in water; but in the latter cafe, particularly when the 
water is fomewhat warm, the blood flows more freely. 
When it is neceflary they fliould ceafe from lucking be¬ 
fore they have fully gorged themfelves, a fmall quantity 
of fait, tobacco, or liiufF, will caufe them to drop off in 
convulflons, and they loon afterwards die. On the con¬ 
trary, when it is confldered neceflary that they fliould 
draw from the wound more blood than their lloniach will 
contain, it is fometimes cultomary to cut off the pofterior 
extremity of their body, out of which the furplus of blood 
will flow as through a tube. 
For fome years it has at different times been afferted, 
that by means of leeches it is poflible to foretell the va¬ 
rious changes of weather, both of heat and cold, of rain 
and fair. The means of doing this have been varioully 
laid down. A French clergyman, who attended to this 
luhjeft for many years, has afferted, that a leech kept in 
a decanter filled with water in a window, will continue at 
the bottom, without any motion, if the following day is. 
about to be ferene and pleafant. If rain is about to fall, 
before or after noon, he fays, that the little animal will 
afeend the fide of the glul's, to the lurface of the water, 
and there continue till very nearly the time when the 
fine weather returns ; and, previoufly to the commence¬ 
ment of high winds, that it will fwim about in the water 
with great rapidity, and will not ceafe from this motion 
till the wind begins to blow. At the approach ofaftorm, 
he informs us, that it will continue entirely out of the 
water even for feveral of the preceding days, appearing 
all the time agitated and reftlefs. The fame perfon, in 
conclufion, afferts, that during frofty weather, the leech 
will continue almofl motionlefs, and as much contracted 
as poflible, at the bottom of the decanter; and that al¬ 
ways during Ihow and rain, it will fix itfelf near the 
mouth of the decanter, and there remain in a ftate of per¬ 
fect tranquillity. There can be no doubt, but that the 
variations tvhich take place in the atmofphere, have con- 
fiderable influence upon thefe animals; but this influence 
is by no means fuch as always to produce the fame ef¬ 
fects upon them. An eafy and fatisfaftory proof may at 
any time be had, by putting four or five leeches into dif¬ 
ferent decanters. It will be found that their motions are 
very uncertain, and that even fometimes each will afford 
a different indication. No dependance, therefore, can be 
placed in them ; and thefe living barometers can deferve 
to be confldered as little better than playthings for chil¬ 
dren. There are feventeen fpecies now afeertained, viz. 
1. Hirudo medicinalis, the medicinal leech : body elon¬ 
gated, olive black, with fix yellow ferruginous lines, 
fpotted with black above, and with yellow beneath; but 
the colours vary at different feafons of the year. The 
body is compofed of numerous annular wrinkles, which 
it can contrafl or expand at pleafure, and by thefe it 
moves itfelf either backward or forward ; mouth fmaller 
than the tail, and armed with three cartilaginous teeth-, 
with which it draws blood; tail compofed of an annular 
mul'cle, by which it has the power of faflening or adher¬ 
ing firmly to any objeft. The leech, like the common 
earth-worm, is hermaphrodite, and copulates in the fame 
manner. Found in flagnant ponds and ditches ; and is 
the fpecies ufed with fuch fuccefs as a phlebotomiil in the 
practice of phyfic. See a correct delineation of this moil 
uf'eful fpecies in the Engraving, at fig. 2. 
2. Hirudo fanguifuga, the horfe-leech: commonly found 
during the fummer-months in pools and flagnant waters, 
ditches, and ponds; it is from four to fix inches long. 
Bod}' - above dull .olive-black, with an ochre margin on 
each fide; beneath paler, with fometimes a few black 
fpots. Tail thicker than the head. This fpecies is larger 
than the preceding, and fucks blood with great avidity, 
and in large quantities; whence this and the medicinalis 
have been often confounded; but are eafily to be diftin- 
guifhed by their fpecific characters. It is delineated in 
the Engraving, at fig. 3. 
3. Hirudo Indica: body depreffed, brown, with a hun¬ 
dred tranfverfe muricate Arise. Inhabits the maritime 
parts of India. 
4. Hirudo lineata : elongated, grey, with four longitu¬ 
dinal black lines on the back ; body annulate with nume¬ 
rous. wrinkles, and with fix deep black eyes in a double 
tranfverfe row. Found early in the fpring in flagnant 
waters ; about an inch and a half long. 
5. Hirudo oftoculata: elongated, with eight eyes in a 
lunate feries. Body fometimes brown immaculate, fbme- 
times fprinkled above with black dots ; fometimes brown 
with yellowifh dots above ; fometimes yellow-brown with 
a knotty line in the middle, and a lateral blackilh one 
pinnate within on the fore-part; fometimes yellowifh with 
longitudinal lines, the middle one knotty, the lateral ones 
with remote red dots; eyes often nine. Inhabits flagnant 
waters, among aquatic plants, and preys on monoculi and 
animalcules ; fifteen lines long. 
6. Hirudo ftagnalis: elongated, cinereous, with two 
eyes. Body whitifh, pellucid, fprinkled with cinereous 
dots, and plaited at the fides; eggs about forty, furround- 
ed by a pellucid circle, cinereous at firll, and afterwards 
brown; the young after exclufion from the ova adhere 
by their tails to the belly of the mother. Inhabits wet 
hollows and rivulets; about nine lines long. 
7. Hirudo complanata : body dilated, cinereous, with a 
double tuberculate line on the back, the margin ferrate ; 
and with tranfverfe bands compofed of three pale lines, 
the margin whitifh ; beneath grey; head pointed, white, 
with fix eyes; tail orbicular, and cinereous. Found in 
fhailow ltreams; about four lutes long. 
8 . Hirudo 
