168 THE COMMON INTEGUMENTS. 



may exist in the blood in a latent state ; for to secrete 

 does appear to be a living act of the glands themselves. 

 The sap of trees owns the same chemical properties, yet 

 forms, by medium through which it passes, either wood, 

 bark, leaves, blossoms, or fruits. 



SECTION XIV. 



OF THE COVERING OF THE BODY, AND OF THE VISCERA. 

 THE COMMON INTEGUMENTS. 



Under the name of skin, exterior parts are bestowed on 

 animals to secure them from injury, and to protect them 

 from cold. These components are the cuticle, or insensible 

 skin, and the cutis, or sensible skin ; and connected with 

 these, are the adipose, cellular membranes, and the panni- 

 culus carnosus. Wliile outside of all are seen hair and 

 hoofs ; the former of which we shall first notice. 



The hair. — Each hair is a little tube, whose bulbous end 

 arises within the cellular web immediately attached beneath 

 the cutis, or true skin : it penetrates the cuticle, and ap- 

 pears exteriorly of indeterminate lengths, figures, and sizes. 

 Thus those of the mane and tail are large and long ; those 

 above the eyes and around the muzzle are stronger, but of 

 diminished length ; while those which extend over the body 

 generally are very short and fine. Each hairy tube is formed 

 of an external coat, derived from the cuticle, within which 

 the horny substance is enclosed. The horny portion is so 

 disposed as to form each hair into an elongated cone. Age 

 is accompanied by a change in the colour of the hair, from 

 a darker to a lighter tint ; the hair which arises after a 

 wound is usually white ; which can be accounted for only 

 by considering the part to be in a state of debility, and to 

 have lost the power of secreting the colouring matter. 

 The inclined position of the hair admirably adapts it to the 

 purposes of protection for which it is designed. This posi- 

 tion sometimes becomes disturbed, partly by a derangement 

 in the vascular bulb of the hair ; and in a greater degree 

 from a derangement in the skin itself; originating in a sym- 



