A N A T O M Y. 
The origin of this mucous fubffar.ce lias not hitherto been 
fufficiently explained; nor has it been fully determined 
what pumofes it ferves in the human body. Haller thinks 
it probable, that it is compofed of a humour tranfuding 
from the furface of the cutis vera. The reafon why it is 
black in the negro has been fuppofed to be for ferving as 
a defence againlt the external heat, by preventing the rays 
of the lun from penetrating his body; but the matter ftili 
lies hid in obfeurity. 
The cutis vera, or [kin properly fo called, is a fubffance 
of very large extent, made up of feveral kinds of fibres, 
clofely connected together, and running in various direc¬ 
tions, being compofed of the extremities of numerous vef- 
fels and nerves. This texture is what we commonly call 
leather ; and it makes, as it were, the body of the (kin. It 
is not eaftly torn; may be elongated in all directions, and 
afterwards recovers itfelf, as we fee in fat perfons, in wo¬ 
men with child, and in fuellings; and it is thicker and 
more compact in lome places than in others. Its thick- 
nefs and compaCtnefs are not, however, always proportion¬ 
al : for, on the pofterior parts of the body it is thicker 
and more lax than on the fore-parts; and on the palms of 
the hands, and foies of the feet, it is both very thick and 
very folid. It is generally more difficult to be pierced by 
pointed inftruments in the belly than in the back. The 
outer furface of this fubffance is furnifhed with fmall emi¬ 
nences, which anatomifts have thought fit to call papillae. 
They appear through its w hole furface like fmall granu¬ 
lations; and feem to be calculated to receive the intpref- 
fions of touch, being the moft eaftly obferved where the 
fenfe of feeling is the molt delicate, as in the points of the 
fingers and palms of the hands; and are fuppofed by ma¬ 
ny to be the capillary filaments of the cutaneous nerves, 
which terminate by fmall radiated pencils: but they muff 
be allowed to be formed like the other parts of the cutis; 
only the nervous fibrillx will be found to be more nume¬ 
rous in them than in other parts. Thefe papillae differ 
very much in figure and difpolition; and they maybedif- 
tinguifhed into feveral kinds. The greateft part of them 
is flat, of different breadths; and feparated by fulci, which 
form a kind of irregular lozenges. The pyramidal figure 
a (bribed to them is not natural; and appears only when 
they are contrafted by cold, by difeafes, by boiling, or by 
fonie other artificial preparation, which alters their ordi¬ 
nary ftruciure. 
The papillae of the palm of the hand, of the foie of the 
foot, and of the fingers and toes, are higher than on the 
other parts of the body; but they are likewife fmaller, 
clofely united together, and placed as it were end-wife with 
refpebt to each other, in particular rows, which reprefent 
on the (kin all kinds of lines, firaight, crooked, waving, 
fpiral, &c. Thefe feveral lines are often diftinftly vilible 
in thofe parts of the palm of the hand which ate next the 
firft phalanges of the fingers The red part of the lips is 
made up of papillae, reprefenting very fine hairs or villi 
clofely united together. There is another particular kind 
under the nails; the papillae being there more pointed, or 
in a manner conical, and turned obliquely toward the ends 
of the fingers. Thofe which are found in the hairy fcalp, 
ferotum, See. are (till of other kinds. 
In inflammations, we oblerve a reticular texture of ca¬ 
pillary veffels, more or lefs extended on the furface of the 
ikin; and curious anatomifts demonftrate the fame thing 
by fine injeTions, which may be looked upon as artificial 
inflammations. Something fimilar to tins has beenfinjebf- 
ed lately by Mr. Baynham of London, who thought it rete 
mucofum-, and afterwards by Mr. Cruikftiank, who calls it 
cuticula quarta. But neither of thefe methods prove, that, 
in the natural date, thefe veffels are blood-veffels; that 
is, that they contain the red portion of tire blood. It is 
more probable that this vafcular texture is only a continu¬ 
ation or produdlion of the very fmall capillaries of the 
arteries and veins; which, in the natural date, tranfmit 
only the ferous part of the blood, w hile the red part con¬ 
tinues its courfe through wider ramifications, which more 
5S7 
properly retain the name of blood-vcffch. This Vafcular 
texture is of various forms and figures fin the different 
parts of the body. It is not the fame in the face as it is 
elfewhere; neither is it alike on all the parts of the face, 
as may be difeovered by the mod ordinary microfcopes; and 
from hence we might perhaps be enabled to give a reafon 
why one part of the body turns red more eaftly than ano- 
ther. T lie fkin has feveral confiderable openings, fome 
of which have particular names; fuch as, the fiffure of 
the palpebra;, the nares, the mouth, the external foramen 
of the ears, the anus, and openings of the parts of gene¬ 
ration. 
Belides thefe, it is perforated by an infinite number of 
fmall holes, called pores, which are of two kinds. Some 
are more or lefs perceivable by the naked eye; fuch as the 
orifices of the milky duffs of the mammae, the orifices of 
the excretory canals of the cutaneous glands, and the paf- 
fage of the hairs. The other pores are imperceptible to 
the naked eye, but vilible through a microfcope ; and their 
exiftenee is likewife proved by the cutaneous tranfipiration, 
and by the effects of topical applications; and from thefe 
two phenomena, they have been divided into arterial and 
venal pores. \Ve ought likewife to obferve the adhefions 
and folds of the (kin. It is everywhere united to the Cor¬ 
pus adipofum ; but it adheres to it much more clofely in 
fome parts than in others, as in the palm of the hand, foie 
of the foot, elbow, and knee. Some plic.e or folds in the 
fkin depend on the ftruCture of the membrana adipofa or 
cellularis, as thofe in the neck and buttocks; others do 
not depend on that membrane, fuch as the ruga; in the 
forehead, palpebrre, See. which are formed by cutaneous 
mufcles, and difpofed more or lefs in a contrary direction 
to thele mufcles. Thefe folds increafe with age. There 
is, belides, a particular kind of folds in the fkin of the 
elbow, knee, and condyles of the fingers and toes; which 
are owing neither to the conformation of the membrana 
adipofa, nor to any mufcle. Laflly, there is a kind of pli¬ 
cae, or rather lines, which crofs the palm of the hand, foie 
of the foot, and correfponding (ides of the fingers and 
toes, in different directions. Thefe ferve for employment 
to fortune-tellers; whole pretended art is contrary to re¬ 
ligion, and defpifed by all men of fenfe. 
In different parts of the body, we meet with fmall glands 
or follicles of an oval form, and feated chiefly under the 
fkin in the corpus adipofum. They are compofed of con¬ 
voluted veffels; but in fome parts of the body they appear 
to be formed of fmall cylindrical tubes, or fijriple follicles, 
continued from the ends of the arteries, and difeharging, 
by fmall excretory dufts, a fat and oily matter, that (erves 
to lubricate and moiften the furface of the (kin. When 
the fluid they fecrete has acquired a certain degree of 
thicknefs, it approaches to the colour and confidence of 
fuet: and from this appearance they have derived the 
name of febaceons glands. They are found chiefly on the 
nofe, ears, axilire, likewife round the nipple, and about 
the external parts of generation in both (exes. Belides 
the febaceous glands, anatomical writers mention other 
fmall fpherical bodies placed every where over the furface 
of the body, in much greater abundance than thofe juft 
mentioned, and named miliary. They are faid to have ex¬ 
cretory duffs that open on the furface of the cuticle, and 
diftil the fweat and matter of infenfible perfpiration ; but, 
after all that has been faid about them, it is certain there 
are no diftinft glands that can be traced by the knife. 
It is chiefly and properly the filamentary fubffance, call¬ 
ed the body of the [kin, which is the univerfal integument 
of the body, and the bafis of all the other cutaneous parts; 
each of which has its particular ufes. The (kin is able to 
reliff external injuries jo a certain degree and fuch impref- 
fions, friftions, ftrokes, &c. to which the human body is 
often liable, as would hurt, wound, and diforder, the parts 
of which it is compofed, if they were not defended by the 
(kin. The papillae are the organs of feeling, and contri¬ 
bute to an univerfal evacuation, called infenfible tranfpira - 
tion. They likewife ferve to tranfmit from without in¬ 
wards. 
