414 TEGUMENTAL SYSTEM. 



should a few white hairs make their appearance, we may con- 

 clude they are the offspring of the injured (not totally destroyed) 

 pulps. 



Of Cellular Membrane. 



Cellular membrane is the material employed in uniting, 

 covering, and defending parts; as well being of itself, under 

 various modifications, a very general component substance. 

 The membranes (both serous and mucous) are resolvable entirely 

 into cellular membrane. Periosteum appears to be nothing more 

 than a modification of it under a condensed form ; and from 

 the periosteum (and not from the muscles, as was formerly 

 supposed) are derived the tendons. Another derivation from this 

 same source are the capsules of joints : they only differ in being 

 thicker in substance, and in as far as they are added to and 

 strengthened by surrounding parts. ^ The faschicB are composed 

 exclusively of cellular membrane ; and from them appears to be 

 derived the cellular substance we find in the composition of the 

 muscles. BiascE mucosa are likewise cellular membrane : indeed, 

 they are much the same as the capsules of joints, containing a 

 similar fluid. Even the animal matter of boties themselves ap- 

 pears to be mainly, if not entirely, cellular membrane. So that 

 cellular membrane may truly be said to be a general compo- 

 nent, as well as the universal connecting medium, of the dif- 

 ferent structures of the body. 



Kinds. — There is said to be two " kinds" of cellular mem- 

 brane in the body: one denominated reticular ; the other adipose. 

 By the " reticular" is meant the true cellular membrane, that 

 which is properly so called ; by the " adipose," the membrane 

 which contains the fat. 



Comparative Quantity. — Cellular membrane exists in greatest 

 abundance immediately underneath the skin, binding it down 

 loosely in some places, in others tightly to the subjacent parts. 

 On the ribs, and more especially about the breast, it is abun- 

 dant and loose in its texture; but upon the belly, and about the 

 head, it is dense, and so short that we can scarcely pinch up the 

 skin, or insert a rowel, though we effect either with the utmost 

 facility in the chest, or underneath the jaw. Although the 

 quantity of this substance depends in some measure on the con- 

 dition of the animal, it is always plentiful in parts possessed of 

 much motion : hence we find it long and loose in the scrotum 

 (wherein it invests the testicles), on the inside of the elbow and 

 thigh, and underneath the jaw. 



Texture. — Cellular membrane is made up of fibres, inter- 

 woven and disposed in such a manner as to form innumerable 



