Its watery solution assumes, when cold, the appearance of jelly ; and, after a par ticular mode of preparation, constitutes glue.
The interstices ofthe cellular substance are lubricated and moistened by a serous or watery fluid, poured out by the exha lant arteries, and again taken in bv the lymphatics. It thus acquires a pllaney and softness, which adapt it particularly to serve as acounecting medium for parts which have motion on each other. The importance of this property will he best understood by observing. the effects of its loss. Inflatnrhation or abscess often causes an induration or consolidation of the cellular texture, by which the integu ments are fixed to the muscles, thc mus cles are firmly united to each other, and to the surrounding parts, and the mo tions of the . whole are considerably im paired.
From the universal extent of this cellu lar texture, two conclusions may be drawn; 1st, it forms the basis of the whole animal fabric, in sloth a way, that if we conceive every part removed but this, the form of the whole would still be expressed in cel lular substance ; 2dly, it forms a connec tion and passage between all parts of the body, howeverremote in situation, or dis similar in structure. For the cells of this substance every where communicate ; as we may collect from facts of the inost common and familiar occurrence. In em phy-sema, where air escapes from the lung wounded by a broken rib into the cellu lar substance, it spreads rapidly from the chest into the most remote parts of the body ; and has even been known to gain admission into the eye-ball. A similar diffusion of this fluid may be effected by artificial inflation, which is commonly practised by butchers on the carcases of calves. In anasarca, or preternatural ac cumulation of fluid in the cellular sub stance, the most depending parts are the most loaded and punctures in these drain the water off from the whole body.
fitlipoutt eubstance, or cells of the cellular substance, in many parts of the body, are destined for the reception of a fluid, termed fat. This is of an unctuous
nature, inflammable, lighter than water, nsually inodorous, and, generally speak ing, similar to the veg.etable oils. It is white in young animals, and becomes yel lower as they advance in age : this differ ence may be seen in the carcases of a calf and cow. It is always more or less fluid in the living subject ; in carnivorous ani mals, and in man, it retains much of its oily.appearance after death ; but in herbi vorous animals it constantly assum e s a con crete form. Dr. Hunter called those parts of the cellular substance which contain fat, adipoua cellular aubatance; and distinguish ed the other by the epithet recticular.
As the fat is deposited in cells, it as sumes in general a kind of granular form. It varies considerably in consistence. That of the orbit is the softest in the body-, and forms a well-known epicurean bonne bouche, in a boiled calf's head. The fat about the kidneys becomes partictilaidy ha,rd after death, and is called suet. The globules or portions of this are very larie, and it contains on the whole less cellular substance than any fat in the body. There is generally a lay er of fat under the skin ; whence a membrana adiposa has been sometimes enumerated as one of the com mon integuments of the body.
Some parts of the body never contain fat, even HI subjects who have the greatest accumulation of this fluid. This is the ca.se with the scrotum, the integtunents of the penis, and the eve-lids : it is obvious that the functions Of these parts would be completely d estroy ed, if they were subject to the enormOus accumulations of fat, which occur in other parts of tbe bbdy. Several of the viscera also neyfr contain any fat, probably for the same r,eason ; this is the case with the brain ayfd lungs.
The quantity of fat varies/according to the age, the state of healtlf, and the pecu liar habit or disposition of tbe individual. It is not found in the early periods of fcetal existence ; and cannot be distinguished with any certainty sooner than the fifth month after conception.