LOU 
kind of mouth, as fome anatomifts have defcrlbed 
it, the entrance into the gullet being abfolutely 
clofed: in the room of all thefe, it is furnifhed 
with a probofcis or trunk, or, as it may be other- 
wife termed, a pointed hollow fucker, with which 
it pierces the ficin, and extrads the human blood, 
it's only fubfillence. This ftomach is partly 
lodged in the bread and back; but the greateft 
portion of it is in the abdomen. When fwollen 
v/ith blood, it appears of a dark brov/n colour, 
which is vifible through the fldn; and varies from 
a faint red to a full or bright brown, accordingly 
as the contents of the ftomach are m.ore or lefs 
corrupted. A¥hen empty, it is of a pale white 
colour; but, when filled, the periftaltic motion is 
plainly difcernible: it then appears working with 
very ftrong agitations; and fomewhat refembles 
one animal contained within another. Superficial 
obfervers are apt to take this for the pulfation of 
the heart; but', if the animal be obferved when 
in the aft of fucking, it will then be found that 
the food takes a direft paffage from the trunk to 
the ftomach, where the remainder of the old ali- 
ment will be feen uniting with the new, and agi- 
tated up and down on every fide. 
If the Loufe be deprived of food for two or 
three days, and then placed on the back of the 
hand, it will immediately fearch for aliment, which 
it will find m.ore readily if that member be rubbed 
till it becomes red: the animal will then turn it's 
head, which is fituated between the mo fore-legs, 
towards the flcin, and diligently explore fome pore: 
when found, it will fix it's trunk therein ; and the 
blood will foon be difcovered, by the afliftance of 
the microfcope, to afcend through the head in a 
very rapid and full ftream. At that time the ap- 
petite of the Loufe is fafficiently keen to feed in 
' any pofture; and it then fucks with it's head 
downward, and it's tail elevated. If, during this 
operation, the {kin be drawn tight, the trunk is 
bound fo faft, that the animal is incapable of dif- 
engaging itfelf; but it more frequently fuffers 
from it's gluttony, fince it gorges to fuch a de- 
gree, as to be crufned by the flighteft preffure. 
Some naturalifts have fuppofcd thefe infefts to 
be hermaphrodites: but this iuppofition feems to 
be erroneous; for Lewenhoeck difcovered that the 
males only have ftings in their tails: and farther 
conjeftures, that the fmarting pain fometimes in- 
flifted by thefe animals is owing to the effeft of 
thefe ftings when incommoded by preffure or 
otherwife. The fame accurate obferver, being 
determined to difcover the true hiftory and man- 
ner of breeding of Lice, deponted two females in 
a black ftocking, wearing it night and day. He 
found, on examination, that in fix days one of 
them had laid above fifty eggs ; and, on diffefting 
it, difcovered as many more remaining in the 
ovary: whence he concluded, that, in the fpace of 
twelve days, it would have laid one hundred. 
Scarcely any animals multiply fo faft as thefe 
unwelconYe intruders, which generally attend 
wretchednefs, difeafe, and hunger; and help to 
fwell the catalogue of calamities incident to the 
human race. It has been quaintly remarked, 
that a Loufe becomes a grandfather in the fpace 
of twenty-four hours : this obfervation cannot per- 
haps be well afcertained ; but nothing is more cer- 
tain, than that the moment the nit (which is no 
other than the egg of the Loufe) emancipates it- 
felf from the fuperfluous moifture, and throws off 
it's fhell, it then begins to breed in it's turn. 
Vol. IL 
LOU 
However, nothing fo much prevents the increafe 
of thefe naufeous infefts as cold and want of hu- 
midity. The nits muft be laid in a warm place, 
and moderately moift, otherwife they feldom pro- 
duce any thing; and this is the reafon why many- 
nits, laid on the hair of the head during the night, 
are deftroyed by the cold of the fucceeding day j 
and fo ftick for feveral months, till they at laft 
lofe their very external form. 
Lice are found on every part of the human 
body ; but more particularly in the heads of chil- 
dren. Thofe which breed on the miners of 
Sweden are faid by Linnaeus to be very large; and 
he is of opinion, that the head and the body differ 
in no refpeft from each other. The pthifiafis, 
or Loufy difeafe, though little known at prefent, 
was frequent enough among the ancients: Antio- 
chus, Herod, Epiphanes, Alcman, Pherecydes, 
Caffander, Calliflienes, and Sylla, are all faid to 
have died of this loathfome diforder. The ufe of 
mercury, which was unknown among the ancients, 
may probably have banifhed it from among the 
moderns; for certain it is, that thofe vermin fel- 
dom attack any of the natives of this country 
who do not invite them either by floth or famine* 
However, it is obfervable that fome conftitutions 
are more apt to breed Lice than others; and that, 
in certain places of different degrees of heat, they 
are inevitably deftroyed on people who in other 
climates are over-run with them. Oviedo re- 
marks, that the Spanifti faiiors, who are generally 
much infefted with Lice, always lofe them in a 
certain degree on their voyage to the Indies; and 
have them again on their approaching the fame 
latitude. in their return. This obfervation, indeed, 
is not only true v/ith refpeft to the Spaniards, 
but all other nations who make the fame voyage: 
for though they fwarm with thefe infefts on their 
firft fetting out, not one of them remains after 
they reach the tropics. In the Indies there are no 
fuch creatures as Lice, however filthy the natives 
may appear. The faiiors continue free from thefe 
vermin till they come about the latitude of Ma- 
deira, on their return home. The extreme fweats 
which thefe laborious people naturally faU into 
between this latitude and the Indies, drown and 
deftroy thefe infefts; and produce nearly the fame 
effefts as rubbing the heads of children with but- 
ter and oil. The perfpiratory fluid is not rank 
in the Indies, as in Europe, and therefore not fa- 
vourable for the produftion of Lice; but, within 
thofe latitudes where the fweat is grofs and rank, 
they are again bred, and their numbers become 
troublefome. 
Such are the Human Lice ; which, from their 
intimate conneftion with mankind, deferve parti- 
cular notice. But it would prove an endlels taf!<: 
to defcribe the various tribes that fall under this 
appellation, and fwarm on every part of nature, 
animate and inanimate. There is fcarcely an 
animal or vegetable that is not infefted with it's 
ov/n peculiar Lice. The fheep, the horfe, the 
hog, and the elephant, are all molefted by them; 
the whale, the fhark, the faimon, and the lobfter, 
are not free from their depredations; while every 
hot-houfe, and every garden, is haunted by fome 
peculiarly deftruftive. Linnaus informs us, that 
he once difcovered a vegetable Loufe on a plant 
newly arrived from America; and, anxious to 
trace the little animal through it's various ftages, 
he carried it with him from London to Leyden, 
where he carefully preferved it during the winter, 
K till 
