ANATOMY. 39 



This membrane acts like a finger in the removal of foreign bodies 

 from the eve. The conjunctiva is a continuous mucous membrane 

 covering the cornea and haw and lining the eyelids. 



The fluid between the lens and the cornea (called "aqueous") is 

 watery, while that between the lens and the retina (called "vitreous") 

 is thicker and like the white of a raw egg. 



The outer covering (seen when the animal shows the white of the 

 eye) is a fibrous tissue called the sclerotic coat. Between it and the 

 retina, is a delicate, dark colored tissue containing the blood vessels 

 and known as the choroid coot. 



ANATOMY OF THE SKIX. 



The skin consists primarily of two parts: The outer, nonvascular 

 layer, called the cuticle or epidermis, and the deep vascular layer, 

 called the corium, dermis, or true skin. 



The epidermis is a scaly covering. The true skin or dermis lies 

 immediately under the epidermis, is much thicker, and contains the 

 roots of the hair, the sweat glands, and the sebaceous glands. 



Sweat glands-are simple tubes extending from the deeper layers of 

 the skin to the surface of the body and pouring out perspiration, 

 which carries with it certain waste materials from the system. The 

 evaporation of sweat cools the body and assists in regulating its tem- 

 perature. 



Sebaceous glands secrete an oily fluid. On parts of the skin which 

 are subjected to much friction these glands pour their oil directly 

 upon the outer surface, as in the sheath, the back of the pastern 

 joints, etc. Usually, however, the glands open into the hair follicles 

 or sacs, and the oily secretion gives gloss to the hair, prevents it 

 becoming dry and brittle, and keeps the surrounding skin soft and 

 supple. 



ANATOMY AND PHYSIOLOGY OF THE FOOT. 



(Plate IX.) 



The horse's foot is composed of three parts, viz: The bony frame- 

 work or skeleton, completed by certain elastic structures of cartilage 

 and fat; the layer of highly sensitive flesh (quick), which covers the 

 framework: and the box or case of horn, called the hoof, which 

 incloses and protects the above-mentioned structures. 



Bones of tin foot. 



The bones of the pastern region and foot form a column extending 

 downward from the fetlock into the hoof, and, as previously stated, 

 are named as follows: Os suffraginis (long pastern bone), os coronse 

 (short pastern bone), os pedis (coffin bone), and os navicvlaris (-hut tic 

 bone). 



