822 INSECTA—FLEA. 
transparency of its external covering. When the louse feeds, the blood 1s 
seen to rush, like a torrent, into the stomach; and its greediness is so great, 
that the excrements contained in the intestines are ejected at the same time, 
to make room for this new supply. 
The louse has neither beak, teeth, nor any kind of mouth. In the place 
of all these, it has a proboscis or trunk: or, as it may be otherwise called, 
a pointed hollow sucker, with which it pierces the skin, and sucks the human 
blood, taking that for food only. The stomach is lodged partly in the breast 
and back; but the greatest portion of it is in the abdomen. When it is 
empty, it is colorless; but when filled, it is plainly discernible, and its mo- 
tion seems very extraordinary. It then appears working with very strong 
agitations, and somewhat resembles an animal within an animal. Superf- 
cial observers are apt to take this for the pulsation of the heart ; but if the ani- 
mal be observed when it is sucking, it will be found that the food takes a direct 
passage from the trunk to the stomach, where the remainder of the old aliment 
will be seen mixing with the new, and agitated up and down on every side. 
There is scarcely any animal that multiplies so fast as this unwelcome 
intruder. It has been pleasantly said, that a louse becomes a grandfather 
in the space of twenty-four hours. This fact cannot be ascertained; but 
nothing is more true than, that the moment the nit, which is no other than 
the egg of the louse, gets rid of its superfluous moisture, and throws off its 
shell, it then begins to breed in its turn. Nothing so much prevents the in- 
crease of this nauseous animal, as cold and want of humidity; the nits must 
be laid in a place that is warm, and moderately moist to produce any thing. 
That is the reason that many nits laid on the hairs in the night time, are 
destroyed by the cold of the succeeding day, and so stick for several months, 
till they at last come to lose even their external form. So numerous were 
the disgusting vermin in Mexico, that the ancient monarchs of that country 
endeavored to rid the subjects of them by imposing an annual tribute of a 
certain quantity. Bags full of lice were found in Montezuma’s palace, by 
the Spanish invaders. 
THE FLEA. 
Ir the flea be examined with a microscope, it will be observed to have a 
small head, large eyes, anda roundish body. It has two feelers, or horns, 
which are short, and composed of four joints; and between these lies its 

Pulex irritans, Lrx. The order Syphonaptera, under which this genus comes, has the 
body compressed; mouth with a sucker of two pieces, inclosed between two articulated 
lamin, which united, form a rostrum or proboscis either cylindrical or conical, and of 
which the base is covered with scales. 
