PHYSIOLOGY OF THE NERVOUS SYSTEM. 



720z 



in them of which the individual is wholly un- 

 conscious, and which he is utterly unable to pre- 

 vent. Sometimes these take place seemingly 

 quite spontaneously; at other times they are 

 excited by the application of a stimulus to some 

 surface supplied by spinal nerves. The move- 

 ments of this kind, which seem to occur 

 spontaneously, exhibit so close a resemblance to 

 voluntary actions as to render it impossible to 

 distinguish them, did not the consciousness of 

 the patient in some cases assure him of the in- 

 active state of his will in reference to them. 



The comparison of the phenomena which 

 occur in pithed or decapitated animals with the 

 actions developed in man under these morbid 

 states, affords most conclusive evidence as to the 

 important question of the connection of these 

 phenomena with the mind. In a pithed or de- 

 capitated animal we can only judge of the 

 exercise of volition or the perception of sensitive 

 impressions by external signs. And so far as 

 these go we are justified in maintaining that, 

 while the mental principle is unextinguished, it 

 nevertheless has lost its influence over or connec- 

 tion with that portion of the cerebro-spinal axis 

 which is separated from the encephalon. But 

 in the human subject we have the evidence of 

 the individual himself, who, from his own con- 

 sciousness, avows the integrity of his will and 

 perception, but admits their dissociation from 

 those parts of the body whose nerves are im- 

 planted in the severed portion of the cord. 



Let us refer to such a case as has been 

 already quoted. A man has fallen from a 

 height and fractured or displaced one or more 

 of his cervical vertebrae ; we find the patient 

 presenting the following phenomena. His 

 trunk and extremities appear as if dead, ex- 

 cepting the movements of the diaphragm, 

 while the head lives. In full possession of his 

 mental faculties and powers, he is, nevertheless, 

 unconscious, save from the exercise of his sight, 

 of any changes which may affect the parts 

 below his head, nor is the utmost effort of his 

 will sufficient to produce a movement of any, 

 even the smallest, of these parts. If the stun- 

 ning effect of the accident have passed off, 

 tickling the soles of the feet will be found to 

 cause movements, of which, as well as of the 

 application of the stimulus, the patient is un- 

 conscious ; the introduction of a catheter into 

 the urethra, which the patient does not feel, 

 excites the penis to erection. The limbs may 

 be irritated in various ways, but without ex- 

 citing any effect which the patient can per- 

 ceive, excepting movements, and these he is 

 aware of only from his happening to see them. 

 It is important to notice that, in cases of this 

 kind, movements are difficult of excitation in 

 the upper extremities, while they are aroused 

 with great facility in the lower. 



In these cases movements may be excited in 

 both lower extremities by passing a catheter 

 into the bladder. Sometimes internal changes, 

 the precise nature of which we cannot always 

 appreciate, but which are often the result of 

 the irritation of flatus or other matters in 

 the intestinal canal, excite movements in the 

 lower or even in the upper extremities, and the 

 patient is disturbed by cramps and spasmodic 



movements, more or less violent, at night. It 

 is very remarkable, that while a patient is almost 

 wholly insensible to external stimuli, he feels 

 and even suffers pain from cramps of this 

 kind. 



In the hemiplegic paralysis which results 

 from an apoplectic clot, or some other lesion 

 affecting one side of the brain, when the para- 

 lysis is complete, the influence of the will over 

 the paralysed side is altogether cut off, sensi- 

 bility, however, generally remaining. In such 

 cases it is wonderful how easily movements 

 may be excited in the palsied leg very rarely 

 in the arm by the application of stimuli to 

 the sole of the foot, or elsewhere with less 

 facility. The patient, who acknowledges his 

 utter inability to move even one of his toes, is 

 astonished at the rapidity and extent to which 

 the whole lower extremity may be moved by 

 touching the sole of the foot, even with a feather. 

 It is proper to add that there is much variety as 

 regards the extent to which these actions take 

 place in hemiplegic cases, owing to causes not 

 yet fully understood ; still they do occur in a 

 large proportion of instances, and in the most 

 marked way. Their developement is frequently 

 in the inverse proportion of the withdrawal of the 

 power of the will. When the paralysis to voli- 

 tion is only imperfect, the effect of stimuli in 

 exciting motions is less obvious, because of the 

 restraining power of the will. 



The cases of anencephalic foetuses may be 

 properly referred to as affording instances of 

 similar movements. In these beings we have 

 no movements which can be supposed to 

 originate in any effort of the will, nor is there 

 any proof of the existence of sensibility. Move- 

 ments, however, of definite kind do occur under 

 the influence of a stimulus applied to the 

 surface. 



Actions of the same kind, i. e., provoked 

 by stimuli applied to some surface to which 

 nerves are distributed, will continue to be 

 manifested in animals after decapitation, not 

 only in the trunk and extremities, but also in 

 those segments of the former with which a portion 

 of the spinal cord remains connected. If the 

 body of a snake or an eel be divided into 

 several segments, each one will exhibit move- 

 ments for some time upon the application of a 

 stimulus. The same thing may be observed in 

 frogs, salamanders, turtles, and other cold- 

 blooded creatures. It may be shown in a re- 

 markable manner in the male frog in the early 

 spring, during the copulating season. At this 

 period an excessive developement of the papil- 

 lary texture of the integuments covering the 

 thumbs takes place; and this seems to be con- 

 nected with the tendency which the male frog 

 exhibits during this period of sexual excite- 

 ment to lay hold on any thing that is brought 

 within the embrace of his anterior extremities 

 and in contact with the enlarged thumbs. If 

 the animal be made to lay hold firmly of any 

 object, two fingers of the observer, for instance, 

 the head and the posterior half of the trunk 

 may be removed, and yet the anterior extre- 

 mities will maintain their grasp with as much 

 firmness as if the animal were unmutilated. 

 And when the frog is in full vigour, they will 



