220 FUNCTIONS OF THE NERVOUS SYSTEM. 



what has previously been occupying the mind ; whilst these seem to leave no 

 impression to be retraced in the waking state, though all that passes in one 

 fit of Somnambulism may be recollected in the next. This has been most 

 remarkably observed in the phenomena of that curious state ^jjjiich is known 

 under the name of Double Consciousness ;* in this, the form of Somnambulism 

 in which there is a consciousness of external impressions, seems to alternate 

 with the condition of ordinary mental activity, and the individual leads (as it 

 were) two distinct lives, recollecting in each condition what happened in 

 previous states of the same character, but knowing nothing of the occurrences 

 of the other.t 



297. We have thus witnessed several varieties in the condition of the bodily 

 system, depending upon partial or complete suspension of the functional activity 

 of the Cerebrum, Cerebellum, and Sensory ganglia. There is no normal con- 

 dition of the Spinal system, which at all corresponds with these ; since its 

 operations are so closely connected with the maintenance of the organic 

 functions, that the suspension of them necessarily induces the cessation of the 

 latter. This is especially the case, however, in regard to the Respiratory 

 ganglion ; for the whole remainder of the Spinal Cord maybe removed, with- 

 out the interruption of the movements which are dependent on that segment 

 of it. Cases have occurred, however, in which the natural performance even 

 of these has been partially or entirely suspended ; and in which the main- 

 tenance of life has for a time been effected, by a voluntary exertion of the 

 muscles of Respiration. The influence of the Will upon the general motor 

 apparatus of Man, seems to predominate so greatly over the Reflex action of 

 the Spinal Cord, that few phenomena which are attributable to the latter 

 ordinarily present themselves ; these are manifested, however, when the in- 

 fluence of the Brain over any part is cut ofl^ as is seen in certain cases of 

 paralysis. These morbid conditions present us, also, with illustrations of other 

 effects of the interruption of the communication between the nervous centres 

 and particular sets of muscles. Thus, the influence of the Will may be cut 

 off, although that of the Instincts, Emotions, and Reflex Function may remain ; 

 or the respondence of the muscles to Emotion may be prevented, whilst they 

 are still capable of Voluntary control, or of Reflex action. Such cases seem 

 to point very clearly to three distinct primary centres of nervous agency ; 

 and to these, the Cerebrum, Sensory Ganglia, and Spinal Cord (including the 

 Medulla Oblongata) have been here assigned as the instruments. We shall 

 next inquire into some other morbid conditions of the system, which seem due 

 to the irregular action of these ; and in this we shall be chiefly guided by the 

 researches of Dr. M. Hall, which have been already slightly glanced at ('211, 



298. Of the Convulsive diseases, it appears that the greater part, if not the 

 whole, may be attributed to a morbid state of the Spinal System of nerves. 

 So completely does the power of producing convulsive movements appear 

 limited to that and to the Emotional system, (no mechanical irritation of the 

 Cerebral substance being effectual in exciting such movements, 286) that, 



* Much interesting information on this and other subjects alluded to in this section 

 may be found in Dr. Abercrombie's Treatise on the Intellectual Functions. 



f In regard to the curious phenomena which are produced by the so-called Mesmeric 

 influence, the, author prefers not offering, for the present, any decided opinion." He has 

 seen enough to satisfy him that they are deserving of investigation ; and to the inquiry 

 into their true character and causes, he purposes to devote himself as opportunity may 

 serve. But there are so many sources of fallacy in the mode in which such inquiries 

 have been usually conducted, that he cannot satisfy himself by relying on the testimony 

 of others, however elevated their characters may be above the mere suspicion of 

 deception, and however firmly he might resf upon their evidence, in regard to subjects 

 of a less complex nature. 



