FUNCTIONS OF THE SPINAL CORD. 



the habitual movements of locomotion, and others which have become " second- 

 arily automatic," may be performed by Man under particular circumstances 

 through the agency of the Spinal Cord alone, under the guidance and direction 

 of the Sensorial centres, or even without such guidance ; the required condition 

 being, that the influence of the Cerebrum shall be entirely withdrawn. There 

 are numerous instances on record, in which soldiers have continued to march in 

 a sound sleep ; and the Author has been assured by an intelligent witness, that 

 he has seen a very accomplished pianist complete the performance of a piece of 

 music in the same state. 1 A case has been mentioned to him by his friend Dr. 

 William Budd, of a patient who labored under that form of epilepsy in which 

 there was simply a temporary suspension of consciousness without convulsion ; 

 and whenever the paroxysm came on, he persisted in the kind of movement in 

 which he was engaged at the moment, having on one occasion fallen into the 

 water through continuing to walk onwards, and having on several occasions 

 (being a shoemaker by trade) wounded his fingers with the awl in his hand by a 

 repetition of the movement by .which he was endeavoring to pierce the leather. 

 Such facts as these add great strength to the probability, that when the Cere- 

 bral power is not suspended, but merely directed into another channel, as in the 

 states of reverie or abstraction, and the attention is entirely drawn off from the 

 movements of locomotion, the continuance of these is due to the independent 

 automatic action of the Spinal Cord, the direction being given to them by the 

 Sensory Granglia. This point, however, will be more fully considered hereafter 

 ( 749); at present it may be remarked that, when a regular train of move- 

 ments is being performed under such conditions, each action may be probably 

 regarded as affording the stimulus to the next ; each contact of the foot with 

 the ground, in the act of walking, exciting the muscular contractions which con- 

 stitute the next step f and each movement of the musician exciting that which 

 has customarily followed it, after the same fashion. Now in all these cases, 

 it seems reasonable to infer, that the same kind of connection between the ex- 

 citor and motor nerves comes to be formed by a process of gradual development, 

 as originally exists in the nervous systems of those animals whose movements 

 are entirely automatic. Whether there is in any case an actual continuity of 

 nerve-fibres, may be reasonably doubted. That such a peculiar continuity is not 

 requisite, in order to allow an excitor impression made upon one part of the 

 Cord to call forth motions through another, may be certainly inferred from the 

 fact, that under particular circumstances we find the influence of such impres- 

 sions radiating in every direction, and extending to nerves which they do not 

 ordinarily affect ( 728). Still there can be no doubt that the nerve-force is 

 disposed to pass in special tracks ; and it seems probable that, whilst some are 

 originally marked out for the automatic movements, others may be gradually 

 worn in (so to speak) by the habitual action of the Will ; and that thus, when 

 a train of sequential actions originally directed by the Will has been once set in 

 operation, it may continue without any further influence from that source. 



727. Another manifestation of the independent power of the Spinal Cord is 

 seen in its influence on Muscular Tension. The various muscles of the body, 

 even when there is the most complete absence of effort, maintain, in the healthy 



1 In playing by memory on a musical instrument, the muscular sense often suggests the 

 sequence of movements with more certainty than the auditory ; and since the impressions 

 derived from the muscles may prompt and regulate successional movements without affect- 

 ing the consciousness, there is no such improbability in the above statement as might at 

 first sight appear. 



2 The truth of this view seems to the Author to be strongly supported by observation 

 of the mode in which infants learn to walk; for, long before they can stand, they will in- 

 stinctively perfoi'm the movements of walking, if they be so supported that the feet touch 

 the ground. 



