Membrane.

PLEURA. All these membranes being destitute of

The Cellular nerves, are of the fame nature as the CELLULAR MEMBRANE*, and are therefore infenfible to

ftimuli.

There

the intestines, along which the lacteals run. The omentum lies immediately under the peritonæum. It is every where a double membrane; 1 speak not of its great fold already mentioned; but every portion of the thin membrane, by itself, may be divided into two thinner membranes, which are joined together by cellular texture, in the cells of which the FAT is depofited. The fecretion here is performed in the most simple manner, like fecretions in plants, there being no glandular apparatus, The fat is diftributed very unequally in the omentum, as you may find it in fome places very thin and transparent, and in other places above an inch thick. The omentum, or cawl, in calves, gives a very beautiful representation of this fact. The ufes of the omentum are first to interpofe between the peritonæum, the intestines, and the stomach, to keep all these parts moist, warm, flippery, and to hinder their adhesion; but most probably its chief ufe is to furnish OIL to the liver to be converted into BILE, which is compofed of alkali (azot and hydrogen) and oil (hydrogen and oxygen). For the fat, though it is depofited in the cells of the omentum, yet must it have fome kind of circulation; otherwife its store would be continually augmenting beyond measure; and as there are here no other excretory ducts but veins, and thefe all terminate in the VENA PORTARUM, which veffel goes to the liver, carrying to its fecretory veffels that fluid, from whence in part BILE is generated; and hence it is a reservoir for the formation of the bile, as the spleen is for the formation of the pancreatic juice.

*The CELLULAR TEXTURE is continued without interruption all over the body, and is infinuated into every recefs. It is compofed, not of fibres laid together or interwoven, nor of small tubes, or veffels, though they run along it, being only adventitious, and no part of its true structure, but of unorganized LAMELLA, like fine fcales. The lamella receding from one another, which partly again uniting tranfverfely, forms cells, in

fuch

There is no doubt of the CUTICLE*, or fearf- The Cuticle. skin, being infenfible, feeing you may cut it, as with corns, which is only an increased cuticle, or burn it

with nitrous acid, until you give it a durable taint, without occafioning the least pain.

such a manner as to communicate together all over from head to foot. If we conceive a fpunge, in which every cell opens into all those that are contiguous to it, we shall form a just idea of the cellular texture. Its CELLS are in fome places fmaller, in others larger; it is dilatable by a very small force, where it is not confined by the refiitance of neighbouring parts. Where its cells are largeft, and its texture looseft, it contains fat, as immediately under the skin, almost over all the surface of the body, between it and the most external muscles; in the intervals, or interftices, between one muscle and another; in the omentum, around the kidneys, &c. This membrane, web, or texture, by laborious diffection, by blowing air into it, by injections, by maceration, hath been found to follow every visible bundle of mufcular fibres, every tendon, every veffel, even every the minutest nerve. We fhall find it conftituting a great part of the cefophagus, ftomach, inteftines, urinary bladder, &c. So that there is no phyfical point in the whole animal fabric, in which there is not a portion of the cellular texture. Its ufe and importance in the animal body is very great. It ferves as a bond of union, by tying and fastening all the parts together, yet in fuch a manner, as not to prevent or obftruct their neceffary motions to contain fat, if required; or marrow; or ferum; or a thin vapour; to render parts smooth, and moift, and flexible; and to hinder them from growing together. It yields a commodious way or road for vessels and nerves to glide along. It furnishes a confiderable part of the linings of the great cavities of the body, and immediately covers and envelops each particular vifcus of the body; infomuch that HALLER, who, of all anatomists, hath most minutely examined, and most fully and extenfively confidered it, declares, "that for certain the far greater part of the animal "body is composed of it."

* Vide page xxix.

THIS

The Rete

Mucofian.

The fat.

THIS GLUTEN* which divides the cuticle from the cutis vera, or true skin, as it cannot easily be feparated from the cuticle, it becomes impoffible to try experiments upon it; but one may reasonably fuppofe, like other fluids, it has no feeling.

The FAT+ is a fluid contained within the cellular membrane. That this fluid may be pierced without inflicting pain, may be seen by a needle thrust into the flesh of a hog, who will fhew no figns of pain, until it has got quite through the fat and reached the flesh below.

The Tendons.

The conftant event of my experiments was, that the animal whofe TENDONI was lacerated, burnt, or pricked, remained quiet, without fhewing any figns of pain, and when part of the wounded tendon remained, it would walk without complaining. After I was fully satisfied of the event, I had no difficulty in discovering the cause, there being no nerves

* Vide page xxix.

+ Vide Vol. I. page 27.

TENDONS are not condensed muscular fibres, but condensed cellular membranes attached to muscular fibres, for the convenience and beauty of this elegant part of our machinery.

that

that I could trace to that part. Seeing therefore in the human body the nerves only are capable of sensation, it is neither unnatural nor improbable that the tendons being destitute of nerves fhould have no fenfation. I have oftener than once feen the tendons laid bare in men, and, emboldened by the experiments which I have made on brutes, I once laid hold, with a pair of forceps, of the naked tendon of the flexor, that bends the third joint of the fore-finger, without the gentleman being in the least fenfible of it. I have likewise seen the fupinator longus chafed with hot oil of turpentine, in order to ftop an hæmorrhage; it occafioned an acute pain in the fkin, but the patient felt none in the tendon. Wherefore there is no need of fear from the accident of the ruptured tendon. I have feen a new cellular substance grow in a few days, and unite the TENDO ACHILLIS that was cut

*

through in a dog. As foon as the edges were united, the animal suffered no inconvenience, and jumped with the same agility upon the chairs as before.

When we cut open, fays BELL of Edinburgh, a fafcia or tendinous membrane, there is little pain: when, as in amputation, we cut the tendons even

The Capfule.

and neat, there is no pain: when we fnip with our fciffars the ragged TENDONS of a bruised finger to cut it off, the patient does not feel: and laftly, when we fee TENDONS of fuppurated fingers lying flat in their fheaths, we draw them out with our forceps, or touch them with probes, without exciting pain. Oil of vitriol has been poured upon each of the parts belonging to a joint, and a piece of cauftic has been dropped into its cavity, but still no pain enfued; nay, some have been fo bold, may I not fay fo vicious, as to repeat these experiments upon the human body, pinching, pricking, and burning the TENDONS of the leg, and piercing them with knives, in a poor man, whofe condition did not exempt him from this hard treatment; who was ignorant of this injustice that was done him, while his cure was protracted, and he was made a cruel fpectacle for a whole city!

In a cat I filled, fays Baron de HALLER, the articulation of the femur with the pelvis with vitriolic acid, without its feeming to feel this violent corrofive. Sometimes inftead of cauftics I have tried the knife, and have tranfpierced the CAPSULE of the knee,

and