CELLULAR substance, in anatomy, or CELLULAR membrane, is the medium which connects and supports all the va rious parts and structures of the body. It is composed of an assemblage of fi bres, and lamina; of animal matter, con nected to each other, so as to form innu merable cells or small cavities, from which its name of cellular is derived. This substance pervades every part of the animal structure. By joining together the minute fibrils of muscle, tendons or nerve, it forms obvious and visible fibres ; it collects these fibres into larger fascicu li ; and by joining such fasciculi to each other, constitutes an entire muscle or nerve. It thus forms an investment com mon to the whole muscle, and bestows on each bundle of fibres, nay, on each fi bre, down to the most minute threads, peculiar sheaths, delicate and tender in proportion to the subtilty of the fibre. It joins together the individual muscles, and is collected in their intervals. It surrounds each vessel and nerve in the body ; often connecting these parts to each other by a firm kind of capsule; and in a looser form joining them to the neighbouring mus cles, &c. When condensed into 'a firm and compact structure, it constitutes the various membranes of the body ; which, by long into in water, may be re solved nto a cellular texture. In the bones, it forms the basis and ground work of their fabric ; a receptacle, in the interstices of • which the earth of bone is deposited. The only parts of the body
in which the cellular texture seems to be wanting are, the proper substance of the brain, the crystalline lens, enamel of the teeth, and the insensible integuments of the body ; viz. the epidermis, nails, and hair. As the cellular substance is entirely soluble in boiling water, it is ascribed by chemists to the peculiar modification of animal matter, termed gelatine. its watery solution assumes, when cold, the appearance of jelly, and, after a particular mode of preparation, constitutes glue.
From the universal extent of this cel lular texture, two conclusions may be drawn. 1, It forms the basis of the whole animal fabric in such a way, that, if we conceive every part removed, ex cept this, the form of the whole would still be expressed in cellular substance. 2. It forms a connection and passage be tween all parts of the body, however re mote in situation, or dissimilar in struc ture. For the cells of this substance every where communicate, as we may collect from facts of the most common and familiar occurrence. The air in em physema spreads rapidly from the chest to .the most remote parts of the body ; it has been known in such a case to gain ad mission into the eye-ball.