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Show ADDlTIONAI.i NOTE ·. II. TliE l~ACULTIRS OF TJIE SENSORIUl\I. Next the long Ilcrvcs unite their Ril vcr lrain, And young en~ntion permeates lhe brain. CANT. I . 1. 250. I. TIIE fibres, which constitute the mu cl s and oro·an. of scn. c, possess a power of contraction. The circumstances attcnd.ing :he exertion of this power of contraction constitute the law · of an11nal motion as the circumstances attending the exertion of the power of attr~ction constitute the Jaws of motion of inanimate matter. II. The spirit of anima.tion is the immediate cause of the contraction of animal fibres, it resides in the brai11 and nerves, and is liaulc to general or partial diminution or accumulation. III. The stimulu of bodies external t the moving organ is the remote cause of the original con tractions of an irnal fibres. IV. A certain quantity of stimulus produces irritatioll, which is an exertion of the spirit of animation exciting the fibres into contraction. V. A certain quantity of contraction of animal fibres, if it be perceived at all, produces pleasure; a greater or less quantity of contraction, if it be perceived at all, produces pain; these constitute sensation. VI. A certain quantity of sensation prochtccs desire or aversion; these constitute volition. VII. All animal motions which have occurred at the same tim e, or in immediate succession, become so connected, that when one of them is reproduced, the other has a tendency to accompany or succeed it. ·when ~brous contractions succeed or accompany other fibrous contractions, the conn xi on is termed association; when fibrous contractions succeed sensorial motions, the connexion is termed causation; when fibrous and sensorial motions reciprocally introduce each other, it is termed catenation of animal motions. The Faculties qf the Sensorium. 13 VIII. These four faculties of the sensorium during their inactive state arc termed irritability, sensibility, voluntarity, and associability; in their active state they are termed as above irritation, sensation, volition, association. J rritation is an exertion or change of some extreme part of the ~ensorium rcsidino· in the muscles or org:llls of sen c, in consequence of the appulses of external bodies. Sensation i an exertion or change of the central parts of the sen~ sorium, or of the whole of it, beginning at some of those extreme parts of it, which reside in the muscles or organs of sense. Volition is an exertion or change of the central parts of the sensorjum, or of the whole of it, terminating in some of those extreme parts of it, which r side in the muscles or organs of sense. Association is an exertion or change of some extreme part of the sensorium residing in the muscles or organs of sense, in consequence of some antecedent or attendant fibrous contractions; see Zoonomia, Vol. I. The word sensorium is used to express not only the medu11ary part of the brain, spinal matrow, nerves, organs of sense and muscles, but also at the same time that living principle, or spirit of animation, which resides throughout the body, without being cognizable to our senses except by it effects. |