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 vertebrx ; we find the patient presenting the following phenomena. Bis trunk and extremities appear as if dead, ex cepting the movements of the diaphragm, while the bead 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 importaidto 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 - I movements, more or less violent, at night. It is very remarkable, that while a patient is ahnost 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 fcetuses 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 bead 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 the left side, A longitudinal section of the cord along the median line in frogs does not cause paralysis; it gives rise, however, to a temporary disturbance of the functions of the cord which soon subsides.t Continuity of the spinal cord and encepha lon is then the condition necessary to establish the control of the former organ over the volun tary movements and sensations of the trunk. The disunion of the cord or any portion of it from the encephalon dissociates the cord or the separated segment of it from all participa tion in mental nervous actions. So long as the cord is united with the brain, it takes a certain share in mental nervous actions, in acts of sen sation and volition ; this, however, it loses when disease or accident separates the one from the other.