228 THR HORSB. 



The superficial layer of the dermis is formed into a series of minutt 

 conical elevations or papilla, projecting into the deep portion of the 

 cuticle, from which they are separated by a very fine transparent mem- 

 brane. This papillary layer is very richlj' supplied with capillary blood 

 vessels and nerves, and is at once the seat of acute sensation and the 

 point from which the nutrient liquid is supplied to the cells of the cuticle 

 above. It is also at this point that the active changes of inflammation 

 are especially concentrated. 



The HAIRS are cuticular products growing from an enlarged papilla 

 lodged in the depth of a sack, hollowed out in the skin aud extending to 

 the deepest layers. The hair follicle is lined by cells of epidermis, 

 which at the bottom are reflected on the papilla and become the root of 

 the hair. The hair itself is formed of the same kind of cells firmly ad- 

 herent to each other by a tough substahce, and overlapping each other 

 like slates on a roof in a direction towards the free end. 



The SEBACEOUS (oil) glands are branching tubes ending in follicles 

 or sacks and opening into the hair follicles, lined by a very vascular 

 fibrous net-work representing the dermis, and an internal layer of cells 

 representing the mucous layer of the cuticle. Their oily secretion 

 gives gloss to the hair and prevents its becoming dry and brittle, 

 and keeps the skin soft and supple, protecting it at once against 

 undue exhalation of water and undue absorption when immersed in 

 that medium. Besides those connected with the hair follicles there 

 are numerous isolated sebaceous glands, opening directly on the sur- 

 face of the skin, producing a somewhat thicker and more odorous 

 secretion. 



The SWEAT GLANDS of the horse, like those of man, are composed of 

 simple tubes, which extend down through the cuticle and dermis in a 

 spiral manner, and are coiled into balls in the deeper layer of the true 

 skin. In addition to their importance in throwing offensive waste pro- 

 ducts out of the sj'stem, these glands tend to cool the skin and the en- 

 tire economy of the animal through the evaporation of their watery 

 secretion. 



Cracked Heels or Scratches. This usually sets in with swell- 

 ing, heat, and tenderness of the hollow of the heel, wifh erections of the 

 hairs and redness (in white skins), with stiffness and lameness, which 

 may be extreme in irritable horses. Soon slight cracks appear trans- 

 versely, aud may gain in depth and width, and may even suppurate. 

 More frequently they become covered at the edges or throughout by 



