322 
This is particularly the cafe during 
winter, at the commencement of which 
they bury themfelves deep in the mud; 
they continue im a femi-torpid ftate, tll 
thé warmth of the enfuing {pring again 
calls them to life, vigour and activity. 
Sea-falt, tobacco, and in general all 
kinds of falt and acrid fubftances, applied 
to the furface of their bodies, are fatal to 
leeches. Some of thefe are always 
adopted for deftroying fuchas faflen upon 
a man or animal, that happens untor- 
tunately to go into waters where they are 
in great numbers. When forcibly torn 
off, they almoft always leave im the 
wound fome part of their head. In this 
cafe the woand has often been known to 
fefter and become a troublefome fore. 
We are informed by Pliny, that Mef 
falmus, a_ perfon of confular dignity, 
even loft his life by an accident of this 
kind. 
Of the leeches employed by furgeans, 
in phlebotmy, that called the medicinal 
leech is preferred to all others. It is, 
however, by no means true, that ‘the 
black or horfe-leech, as it is ufually de- 
nominated, has any poifonous properties, 
notw ithitanding the prefudices which, on 
this fuppofition, have long been enter- 
tained againft it. 
Leeches ought to be collected in the 
fpring of the year, if poffible, and thould 
be kept in vellels of pure {pring water, 
which muft be changed very frequently, 
particularly in fummer. If they are very 
numerous, they ought to have frefh water 
as often as twice a.day; but if they are 
only in finall quantity, once in two days 
may be fufficient. All the flime which 
accumulates upon their bodies, flould 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 
tiiefe animals ; and on the fatter account, 
particularly, an apothecary’s or druggift’s 
ihop, isone of the worlt places in which 
they can be kept. The perfon employed 
in removing them from one vetlel into 
another, fhould have bis hands in every 
re{pect as clean as pofiible. 
There is no great art in applying 
leeches to the body; but a perfon who is 
accuitemed to it, will alw ays do it better 
than one who is not. In the moft ex- 
perienced . hands, however, they will 
fometimes refufe to faiten themfelves, 
either from not being hungry at the time, 
or trom the furface of the fkin, or the 
Obfervations on the Natural Hiftory of Leeches. 
~they foon afterwards die.. 
[May 1, 
blood, on their making the attempt, be- 
ing unpleafant to their taite. The wound 
they make out of water, is more fenfible 
than what they make in water; bat in 
the iatter cafe, particularly when the 
water is fomewhat warm, the blood flows — 
more freely. When it is necefiary they 
fhould ceafe from fucking before they 
have fully gorged themielves, a finall 
quantity of falt, tobacco or fnuff, will 
caufe them to drop off in convulfions, and 
On the con- - 
trary, when it is confidered necefiary that 
they fhould draw from the wound more 
blood than their ftomach will contain, 
it is fometimes cuftomary to cut off +e 
potterior 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 poifible to foreteli the various 
changes of weather, both of heat and 
cold, of rain and fair. The means of 
doing this have been varioaily Jaid down. 
A French clergyman, who attended to 
this fubject for many years, has. afferted, 
that aleech kept ina decanter filled w ith 
water in a window, will continue at the 
bottom, without any motion, if the fol- 
lowing day is about to be ferene and. 
pleafant. If rain is about to fall, before — 
or after noon, he fays, that the little ani- 
mal will afcend the fide of the glafs, to 
the furface of the water, and there con- 
tinue till very nearly the time, when the 
fine weather returns; and, previouily to 
the commencement of high winds, that it 
wil fwim about in the water with gréat 
rapidity, and will not ceafe from ae mo- 
tion till the wind begins to blow. At the 
approach of a ftorm, he informs us, that 
it wall continue entirely out of the water - 
even for feveral of the’ preceding days, 
appearing all the time agitated and reft- 
lefs. The fame perfon, in concluhon, 
atierts, that during frofty weather, the 
leech will continue alnoft motionlets, 
and, as much contracted as poiiible, at 
the bottom. of the decanter; and that 
always during fnow and.rain, it will fix 
itfelf near the mouth of the decanter, and 
there remain in a ttage of perfect tran- 
quillity. 
There can be no doubt, but that the 
_variations which take place i in the atmo- 
{phere, have contiderable influence upon 
thefe animals; but this influence is by no 
means fuch, as always to produce the 
fame effects upon them. An eafy and 
fatisfactory proof may at any time be 
had, by putting four or five leeches into 
different 
