112 
ON LEECHES. 
subject, by M. Blavette, in the “ Correspondance Veterinaire de 
Fromage de Feugre.” This differed in many points from the cases 
which I had observed ; and I resolved to again collect together my 
ideas on the subject, as there were many things with regard to the 
manner in which leeches live, and the mischief they effect in the 
horses’ mouths, which M. Blavette had not stated, and which ap- 
peared to me to deserve to be known. 
I wrote a new treatise on this subject, which, some time after- 
wards (in 1817), I addressed to “ The Royal and Central Society 
of Agriculture,” and it is from this latter work that I have ex- 
tracted the following details : — 
Iti all the warm climates (those on whose authority I can depend 
have assured me that it is so in Naples and Italy), leeches there in- 
sinuate themselves into and fix themselves, and remain an indeter- 
minate time, in the mouths of horses, frequently living there until 
they are discovered and removed. Leeches seldom do this, either 
in temperate or in cold countries. I confess that it seems to me 
difficult to assign a reason for this difference ; for, if the well-known 
love of leeches for the blood of animals accounts for their taking 
up their abode in the mouths of horses in meridian and hot cli- 
mates, why should not those in temperate countries, who have the 
same taste for blood, act the same, if there was not here some other 
cause for the difference ? 
The four causes which contribute to render agreeable and easy 
the stay which leeches are pleased to prolong in the mouth of 
the horse are, first, their taste for the flesh and blood of animals ; 
secondly, the moist heat of this cavity ; thirdly, the facility with 
which they can fix their teeth ; fourthly and lastly, the still greater 
facility with which they can disgorge themselves constantly by 
means of the causes which I have mentioned ; likewise those in 
Spain, which, having once fixed themselves, live there until they 
are either driven or pulled out by some cause or force. 
It is with the water taken in drinking from fountains, rivers, 
or brooks, that the leeches are first introduced into the mouths of 
horses ; where they attach themselves to the most delicate parts, 
and which are, at the same time, those where they will be the 
least tormented by the movements of mastication or by the passage 
of the food. The leech, thus lodged in the horse’s mouth, adheres 
only by the anterior part of his body ; that is to say, by that part 
which answers to his head, and where his three teeth are placed, 
and where he has the faculty of making an incision in the skin and 
sucking the blood. The rest of the body remains free and floating, 
yielding to all movements, and sometimes extended so that it is 
struck by the tongue or the jaws ; nevertheless, the adherence of 
the leeches to the parts on which they have once established them- 
