120 



THE SENSORIAL FUNCTION. 



brutes have no concern and no idea beyond their food and reproduction ; and 

 hi their domesticated state they are destined to be the servants of man. The 

 acuteness of their senses, and the preponderance of animal power, qualify them 

 for this purpose ; but were proportionate intellectual capacity added to this 

 were they made conscious of their strength, they would burst their bonds, and 

 man would, in his turn, be the victim and the slave. The cortical part is found 

 in each in the proportion in which it would seem to be needed for our purposes, 

 in order that intelligence should be added to animal power. Almost every 

 mental faculty, and almost every virtue, too, may be traced in the brute. The 

 difference is in degree, and not in kind. The one being improved by circum- 

 stances and the other contaminated, the quadruped is decidedly the superior. 



From the medullary substance as already stated proceed certain cords or 

 prolongations, termed nerves, by which the animal is enabled to receive impres- 

 sions from surrounding objects, and to connect himself with them ; and also to 

 possess 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 (A, p. Ill) springing from a prolongation of the 

 brain, and yet within the skull, wanders to different parts of the frame, for im- 

 portant purposes connected with respiration or breathing. The act of breathing 

 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 q 

 a farther prolongation of the brain, and running through a cavity in the bones 

 of the neck, back, and loins, and extending to the very tip of the tail other 

 nerves are given off at certain intervals. This cut delineates a pair of them. 



The spinal cord 

 o, is combined of 

 six distinct co- 

 lumns or rods, 

 running through 

 its whole length 

 three on either 

 side. The two 

 upper columns 

 the portion of 

 spinal marrow re- 

 presented in our 

 IS cut, is supposed to 



be placed with its inner or lower surface toward us proceed from those tracks of 

 the brain devoted to sensation. Numerous distinct fibres spring abruptly from 

 the column, and which collect together, and, passing through a little ganglion or 

 enlargement, d an enlargement of a nervous cord is called a ganglion become a 

 nerve of sensation. From the lower or inner side, a prolongation of the track 

 devoted to motion, proceed other fibres, which also collect gradually together, 

 and form a nervous cord, c, giving the power of motion. Beyond the ganglion the 

 two unite, and form a perfect spinal nerve, 6, possessing the power both of 

 sensation and motion ; and the fibres of the two columns proceed to their 

 destination, enveloped in the same sheath, and apparently one nerve. Each 

 portion, however, continues to be wrapped in its own membrane. They arc 

 united, yet distinct; they constitute one nerve, yet neither their substance nor 



