402 NOTICE OF THE LATE SIR CHARLES BELL. 



rium intelligence of the condition of their extremities, or sensation. It was 

 taught that, in some mysterious manner which no one could explain, these two 

 impulses might be simultaneously communicated along the same cord, in oppo- 

 site directions, without impairing the efficiency of either. This proposition was 

 certainly startling ; but so long as each spinal or vertebral nerve was regarded as 

 a simple cord, composed of one bundle of similar filaments, the inference was in- 

 evitable ; for if we divide the trunk of one of these nerves, at any point, we leave 

 unimpaired the power of motion, and the sensation of the parts which intervene 

 between the point of section and the brain ; but we paralyze at once both motion 

 and sensation in the parts over which its remoter ramifications are distributed. 

 The cord thus divided was, therefore, necessarily and truly inferred to be the 

 channel through which volition acted to move the muscles, and through which 

 sensation was communicated from other parts of the body to the sensorium. 



It is nevertheless true, that physiologists had not been uniformly satisfied 

 with this theory. The fact that a limb, which had lost the power of voluntary 

 motion, often retained sensation, had led some discerning men, at an early time, 

 to question whether there might not be different nerves for motion and for sen- 

 sation. GALEN asserted this opinion in a part of his writings ; but he elsewhere 

 maintains that one nerve may minister to both offices ; that motion is active, and 

 sensation passive ; and that a nerve may retain this passive power after it has 

 lost that which is active. 



BOEMIAAVE, following GALEN, asserted that there were two kinds of spinal 

 nerves the one serving for motion, the other for the use of the senses. Speak- 

 ing of the spinal marrow, he uses these remarkable expressions : " Ex hac me- 

 dulla exit duplex genus nervorum, unum motui, alterum sensuum inserviens, nee 

 unquam inter se communicans ;" and then he adds the inquiry, " Quis dicet hie, 

 hoc movet hoc sentit ? " This was certainly a striking and ingenious specula- 

 tion ; but BOERHAAVE did nothing towards solving the question he had put, or the 

 doubts he seemed desirous to raise ; accordingly, these speculations produced no 

 change in the opinions of anatomists and physiologists, and the old theory not 

 only maintained its ground, but appeared to be confirmed by further investi- 

 gations. 



The renowned HALLER, who carefully investigated this subject, and who 

 must have been well acquainted with the writings both of GALEN and of BOER- 

 HAAVE, rejects a theory which neither of these distinguished authors had supported 

 by any evidence, and which they had not even uniformly maintained. " But I 

 know not," says HALLER, " a nerve which has sensation without also producing 

 motion ; the nerve which gives feeling to the finger, is also that which moves the 

 muscles ; and the fifth nerve of the brain branches to the papillae of the tongue, 

 and also to the muscles." 



Dr ALEXANDER MONEO maintained similar opinions ; and he combated the 



