80 



THE SENSORIAL FUNCTION. 



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, b, 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 are united, yet distinct; they constitute one 

 nerve, yet neither their substance nor their office is confounded. Our cut, closely 

 examined, will give at b some idea of the manner in which these distinct fibres are 

 continued; — each covered by its own membrane, but all enveloped in a common 

 envelope. 



All these nerves are organs of sensation and motion alone; but there are others 

 whose origin seems to be outside of and below the brain. These are the sympathetic, 

 so called from their union and sympathy with all the others, and identified with life 

 itself. They proceed from a small ganglion or enlargement in the upper part of the 

 neck, or from a collection of little ganglia in the abdomen. They go to the heart, and 

 it beats, and to the stomach, and it digests. They form a net-work round each blood- 

 vessel, and the current flows on. They surround the very minutest vessels, and the 

 frame is nourished and built up. They are destitute of sensation, and they are per- 

 fectly beyond the control of the will. 



The reader, we trust, will now comprehend this wonderful, yet simple machinery, 

 and be able, by and by, to refer to it the explanation of several diseases, and particu- 

 larly of the operation to which we have referred. 



Two of the senses have their residence in the cavity of the cranium — those of hear- 

 ing and sight. 



They who know anything of the horse, pay much attention to the size, setting on, 

 and motion of the ear. Ears rather small than large — placed not too far apart — erect 

 and quick in motion, indicate both breeding and spirit; and if a horse is frequently in 

 the habit of carrying one ear forward, and the other backward, and especially if he 

 does so on a journey, he will generally possess both spirit and continuance. The 

 stretching of the ears in contrary directions shows that he is attentive to everything 

 that is taking place around him, and, while he is doing this, he cannot be much 

 fatigued, or likely soon to become so. It has been remarked that few horses sleep 

 without pointing one ear forward and the otlier backward, in order tl.at they may 

 receive notice of the approach of objects in every direction.* 



The ear of the horse is one of the most beautiful parts about him, and by few things 

 is the temper more surely indicated than by its motion. The ear is more intelligible 

 even than the eye, and a person accustomed to the horse, and an observer of him, can 



* " When horses or mules march in company at right, those in front direct their ears for- 

 wards ; those in the rear direct ilicin backward ; and tliose in the conlre, turn them laterally 

 or across ; the whole troop scciniiiL' iliiis to he actuated by one feeling, which watches the genera, 

 safety." — Arnott's EUmmls of Physic , vol. i., p. 47S. 



