OUTLINE OF THE STKUCTURE OF IHE HORSE. 53 



certain cords or prolongations, termed nerves, by which the 

 animal is enabled to receive impressions from surrounding 

 objects, and to connect himself with them, and also to pos- 

 sess many pleasurable or painful sensations. One of them 

 is spread over the membrane of the nose, and gives the sense 

 of smell; another expands on the back of the eye, and the 

 faculty of sight is gained; and a third goes to the internal ' 



structure of the ear, and the animal is conscious of sound. 

 Other nerves, proceeding to different parts, give the faculty 

 of motion, while an equally important one bestows the power 

 of feeling. 



" One division of nerves, (see A, in cut,) springing from 

 a prolongation of the brain, and yet within the skull, wan- 

 ders to different parts of the frame for important purposes 

 connected with respiration or breathing. The act of breath- 

 ing is essential to life, and were it to cease, the animal would 

 die. These are nerves of involuntary motion ; so that, whether 

 he is awake or asleep, conscious of it or not, the lungs heave, 

 and life is supported. 



"Lastly, from the spinal cord, (see q, in cut,) a further 

 prolongation of the brain, and running through a cavity iii 

 the bone of the neck, back, and loins, and extending to the '^ 



very tip of the tail, other nerves are given off at certain in- 

 tervals. The spinal cord is combined of six distinct columns 

 or rods, running through its whole length, three on either 

 side. The two upper columns proceed from those tracks of 

 the brain devoted to sensation. Numerous distinct fibers 

 spring abruptly from the column, which collect together, 

 and, passing through a little ganglion or enlargement, (an 

 enlargement of a nervous cord is called a ganglion,) become 

 a nerve of sensation. From the lower or inner side — a pro- 

 longation of the track devoted to motion — ^proceed other 

 fibers, which also collect gradually together, and form a 

 nervous cord, giving the power of motion. Beyond the 

 ganglion the two unite and form a perfect spinal nerve, 

 possessing the power of both sensation and motion ; and the 

 fibers of the two columns proceed to their destinations, en- 



