TRANSACTIONS OF THE SECTIONS. 677 



of nerves, the hard portion of the seventh, the vagus, the spinal 

 accessory, the glosso-pharyngeal, the lingual, and the sympa- 

 thetic nerves. Upon the properties of the first, second, third, 

 fourth, sixth, and the soft portion of the seventh pairs of nerves 

 no doubt or discrepancy exists. 



It has long been known that the properties of the cerebral 

 nerves are various. Thus, one nerve governs the function of 

 motion ; another that of some specific sensation, as of light or 

 soimd; and these properties are held independently of each 

 other. To understand clearly the properties of nerves, it is also 

 necessary to apply the test of experiment to their roots ; for 

 branches from two or more roots unite to form one nerve ap- 

 parently, which may then assume two distinct properties, that 

 is, the peculiar property of each root. This is exemplified in 

 the origin and distribution of the nerves of the face. 



The apparent discrepancies in the results of experiments 

 probably depend much upon the indefinite manner in which cer- 

 tain physiological terms have been employed. Thus, sensation 

 has been coupled ivith consciousness in some instances, and in 

 others it has been supposed to exist without consciousness. In 

 the present report the term sensation implies consciousness. It 

 is considered as identical vf\ih.feelitig, and when violently excited 

 it becomes pain. And this is manifested by general and in- 

 stantaneous efforts or struggles. These are, therefore, the signs 

 of sensibility . 



Three modes of judgement have appeared as necessary to be 

 kept in view in the present inquiry in reference to the above de- 

 finition : 



1. It was observed that when a nerve of unequivocal sensibi- 

 lity was pricked or pinched, an immediate and general struggle 

 followed. The facial branches of the fifth nerve are examples. : 



2. That when a nerve as unequivocally devoted to motion is 

 pinched, there is an immediate contraction of the muscles which 

 that nerve supplies, and of no other muscles, 



3. That on pinching the par vagum, neither of the phaeno- 

 mena above noticed occurs ; but by continuing the compression 

 for a few moments, an act of respiration and of deglutition fol- 

 lows, with a tendency to struggle and cough. 



Of these three phaenomena the first only is considered as in- 

 dicating the property of sensation, or the power in the nerve 

 subjected to experiment to transmit sensible impressions. 



The movements in the third instance appear to arise from 

 secondary causes, the mechanical irritation of the nerve not 

 being attended with immediate consciousness. 



1. Experiments upon the Facial Nerves. — These nerves go- 



