458 
P E D 
ticular defcription unneceflary. As a fpecies, it is diftin- 
guiflied by its pale livid colour, and lobated oval abdo¬ 
men, with five joints to the antennas. It is produced 
from a fmall oval egg, popularly called a nit, which is 
fattened or agglutinated by its fmaller end to the hair on 
which it is depofited. From this egg proceeds the infedl, 
complete in all its parts, fit to propagate its fpecies im¬ 
mediately, and therefore differing only from the parent 
animal in its fmaller fize. Such diminutive fpecimens 
are far preferable, for microfcopic obfervation, to the full- 
grown infedl, fhowing in a more diftindl manner the dif- 
pofition of the vifcera, mufcles, &c. &c. When thus 
examined by the microfcope, the principal appearances, 
according to Mr. Adams, are as follow: “In the head 
we may diftinguifh two fine black eyes, looking back¬ 
ward and fenced with hair; near thefe are the two anten¬ 
nae, each of which has five joints fet with fhort briftles; 
the fore-part of the head is rather long, the hinder more 
round or obtufe; there is a fmall part that projects from 
the nofe or fnout, this ferves as a (heath or cafe to the 
probofcis or piercer, which the creature thrufts into the 
fkin to draw out the blood and humours which are its 
deftined food, for it has no mouth which opens in the 
common way. This probofcis has been eftimated to be 
feven-hundred times fmaller than a hair; it is contained 
in another cafe within the firft, and can be drawn in or 
thruft out at pleafure. The (kin is hard and tranfparent. 
From the under fide proceed fix legs, each of which has 
five joints, and terminates in two unequal hooked claws ; 
thefe it ufes as we would a thumb and finger; there are 
hairs between the claws, as well as all over the legs; the 
body finifhes in a cloven tail, which is generally covered, 
and partly concealed, by hairs. From the extreme tranf- 
parency of its (kin, the internal parts may be feen to 
greater advantage than in any other infedl; as, the va¬ 
rious ramifications of the veins and arteries, in which a 
kind of regular pulfation may be obferved, as well as the 
periftaltic motion of the inteftines, which is continued 
from the ftomach to the tail. When the loufe feeds, the 
blood ruflies like a torrent into the ftomach, moving 
with fo ftrong a propultion and contraction, as appears 
very curious. The digeftive powers are fo great, that the 
colour of the blood changes in its pafiage from thickand 
black at its firft entrance to a fine ruby colour in the in¬ 
teftines, and nearly white in the veins. Its greedinefs is 
fo great, that the excrement contained in the inteftines is 
ejected at the fame time, to make room for this new fup- 
p'y-” 
It is affirmed by Leeuwenhoek that the male is fur- 
nifhed at the extremity of the abdomen with a fting; and 
that it is this inftrument which caufes the chief irritation 
fuffered from thefe animals; the aCtion of the fucker 
hardly feeming to have caufed any perceptible pain on 
the (kin of his hand. The male is readily diftinguifhed 
from the female by having the tail or tip of the abdomen 
rounded : in the female it is forked or bifid. The fame 
accurate obferver (Leeuwenhoek), being defirous of 
earning the proportion and time of the increafe of thefe 
infeCts, placed two lice in a black filk flocking, which 
he continued to wear day and night. He found that in 
fix days, one of them had laid fifty eggs; and upon dif- 
feCling it, he found as many more in the ovary : he there¬ 
fore concluded that in twelve days it would have laid 
an hundred eggs : thefe eggs, hatching in fix days, which 
he found to be their natural time, w'ould probably pro¬ 
duce fifty males, and as many females ; and thefe females, 
coming to their full growth in eighteen days; might each 
of them be fuppofed, after twelve days more, to lay alfo 
an hundred eggs; which in fix days farther, (the time 
required to hatch them,) might produce a younger brood 
of five thoufand; fo that in eight weeks a loufe might 
fee five thoufand of its own defcendants! 
■ It will be readily fuppofed, that the figures we (hall 
give of thefe minute infeCts will be confiderably magni¬ 
fied, that their parts may be brought diftinClly before the 
P E D 
eye of the reader. Fig. i. however, of the annexed Plate, 
(hows the common loufe of its natural fize; fig. a. the 
fame magnified ; fig. 3. more confiderably magnified, and 
lying on its back. 
| 3 . Body-loufe: lefs compaCt and paler. Thefe pedi- 
culi are bred abundantly among the inhabitants of fordid 
dwellings, of gaols, and workhoufes, &c. and in fuch 
fituations prey upon perfons of all ages indifcriminately. 
There is, however, alfo a peculiar ftate of (kin in people 
advanced in years, and connected with thedifeafe, which 
has been denominated Prurigo fenilis by Dr. Willan, in 
which they are generated, notwithftanding every atten¬ 
tion to cleanlinefs or regimen, and multiply fo rapidly, 
that the patient endures extreme diftrefs from their per¬ 
petual irritation. The nits or eggs are depofited on the 
fmall hairs of the (kin ; and the pediculi are only found 
on the (kin or on the linen, and not under the cuticle, as 
fome of the old authors have reprefented. Many mar¬ 
vellous (lories, indeed, are related by Foreflus, Schenckius, 
and others, refpedling lice bred under the fkin, and dif- 
charged in fwarms from abfcefles, ftrumous ulcers, and 
vefications: and many individuals of great note are ftated 
to have died, in ancient times, from the multitude of 
thefe devouring pediculi. Thus Plutarch relates of 
Sylla : “ It was long before he perceived that he had an 
ulcer within his body ; but at laft the flefh putrefied, and 
produced fuch a quantity of lice, that, though many 
perfons were employed day and night in deftroying them, 
yet they increafed much fader than they could be re¬ 
moved ; and to fuch a degree did the diftemper prevail, 
that his clothes, baths,- bafins, and food, were polluted 
with that perpetual flux of corruption and vermin. He 
went many times in the day into the water, to fcower and 
cleanfe his body, but all in vain; the vermin multiplied 
fo fall as to baffle every attempt to deftroy them.” The 
biographer adds, “It is faid, that among the ancients, 
there died of this difeafe Acaftus the fon of Pelias, and 
nearer our own times Alcmason the poet, Pherecydes the 
philofopher, Callifthenes the Olynthian, during the time 
of his imprifonment, and Mutius the lawyer : and, if it 
be proper to add to thefe a perfon not diftinguifhed by 
any merit or virtue, Eunus, a fugitive (lave, who was au¬ 
thor of the war in Sicily, called the fervile war, and who 
was taken and carried prifoner to Rome, died likewife of 
this ficknefs.” (See Plutarch’s Life of Sylla ; alfo, Plin. 
Hid. Nat. lib. xxvi. cap. 13. who, fpeaking of phthiriafis, 
obferves, “ qua Sylla dictator confumptus eft.”) Herod, 
Ennius, and by fome Plato, are faid alfo to have been de- 
flroyed by the loufy difeafe. In more recent times, 
Amatus Lufitanus has affirmed, that he was witnefs to the 
cafe of a gentleman, who perilhed miferably in this dif¬ 
eafe : “ for fo univerfally did thefe infedls fwarm over his 
body, that two negro fervants were entirely employed 
in collecting bafkets-full from his perfon, and carrying 
them to the fea.” Amat. Lufit. Contur. iii. Cur. 58. 
See alfo Foreft. Obf. Med. lib. viii. obf. 14. Johan. Schenck. 
Obf. Med. lib. v. obf. 2. 
The mode in which pediculi are generated being now 
well afcertained, and fuch fatal fwarms of them being al¬ 
together unknown in modern experience, we can fcarcely 
give credit to thefe accounts. They are not only in all 
probability much exaggerated, but have actually origi¬ 
nated in miftake. The larvae, or grubs, of feveral winged 
infeCts, efpecially thofe of the common fly (Mufca domef- 
tica), and of the black beetle (Tenebrio inolitor), not 
unfrequently breed, both in the internal paffages, and in 
external wounds, of the human body. And in warm 
climates, the flies are fo numerous about the perfons of 
the fick, that the utmoft care is requifite to prevent the 
generation of larvae from the eggs which they depofit, 
not only in fuperficial wounds, but in the noftrils, mouth, 
gums, &c. fometimes even penetrating to the brain itfelf, 
and producing death. From this view of the lubjeCt, 
therefore, little doubt can remain, that the fatal cales of 
antiquity, above alluded to, occurring in the warmer re¬ 
gions 
1 
