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sneezing, cough, hiccup, vomiting, deglutition, the evacuation of the 
bowels and bladder, and such acts as the sudden withdrawal of the 
foot when a drop of boiling water falls on it. It is further shown 
that in such acts generally, there is a consciousness of the impres- 
sion and a consciousness of the muscular act determined by it, but 
that there is no consciousness of the exercise of any intervening 
power, or of the effect of what Whytt terms the sentient principle. 
It is further stated, that while the discovery of numerous before 
unnoticed relations between the several parts of the nervous system 
has largely explained the conformation of the nervous organism, 
there has not been a corresponding advance in the knowledge of the 
activities therein operative, so that the same forms of expression 
are applicable to Whytt’s system and to the matured state which his 
views have now assumed. 
The Memoir goes on to state that Unzer was the first who fol- 
lowed Whytt in such a mode of considering nervous action ; that 
while it is acknowledged that Unzer’s book is one of great ability, 
it is a mistake to think that his reflex action of nerves is an advance 
upon Whytt’s,- — that it is, on the contrary, retrograde, as the reflex 
action which he describes is made dependent on communications of 
nerves in their course analagous to the explanation given by Willis 
of sympathy. That Prochaska did make a considerable advance ; 
that reflex action in his hands has its seat in the common sensorium 
or cranio-spinal axis, or excludes the cerebrum and cerebellum, 
while he describes it as a law written on the medullary pulp of the 
sensorium, — that is, he ascribes it to no principle or force, though 
his expression implies the latent existence of such a principle or 
force. That Marshall Hall is entitled not only to the credit of 
having given a new impulse to the study of this part of physiology, 
but of having made the great advance of showing that each segment 
of the spinal cord and medulla oblongata possesses a separate power 
of imparting reflex action to the nervous fibrils which originate 
in it, whenever certain impressions are brought to that segment by 
afferent nerves which terminate there. 
In reference to Whytt’s views of sympathy which belong to the 
second of the works mentioned before, his sympathetic actions come 
under the same head as the non-vital involuntary motions, or de- 
pend on impressions reflected into motions through the nervous 
centre. The sympathetic sensations are either the result of mental 
