PHYSIOLOGY OF THE NERVOUS SYSTEM. 
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- 
Biante) 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 vertebre; 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 possessien 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 
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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 lis 
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 
