THE LINOERINa ADMIRERS OF PHRENOLOGY. 
381 
ductors, and such nerve fibres are the essential elements in all 
the nerves throughout the body. Nerve corpuscles are bodies of 
which it is only necessary to say that they present a variable 
number of poles or branches, and there is no reasonable doubt 
that those poles are in direct continuity with nerve fibres. 
According to circumstances little understood, these corpuscles 
have the property of modifying impressions of nervous influence, 
and of directing them into different channels with which their 
poles communicate. Now the white substance of the brain and 
spinal cord contains only nerve fibres without any nerve cor- 
puscles, these latter being found exclusively in the grey sub- 
stance. It is quite plain, therefore, and universally recognised, 
that the white substance is only useful as containing channels of 
communication between different parts of the grey, and also 
between grey substance and the muscles and sensitive parts 
throughout the body. But even grey substance is not always 
or even generally capable of being affected directly by the 
consciousness; and in the case of the spinal cord, it is very 
certain that consciousness resides in no part of it, either white 
or grey. The spinal cord is the centre with which are connected 
the nerves of the muscles and integuments of the greater part 
of the body, and in the ordinary actions of the body what usually 
happens is this, that impressions made by the contact of external 
objects on the terminations of sensory nerves in the integument 
are transmitted by them to the nerve corpuscles of the cord, and, 
through series of these, conducted to the parts of the brain 
which are in immediate connection with consciousness ; while 
also, when the mind wills certain movements of the body, the 
stimulus proceeds from those parts of the brain, and, by some 
altogether unknown mechanism, is ultimately so distributed 
that there extend from the grey matter of the cord impressions 
along the nerves so adjusted as to produce precisely that amount 
of contraction of muscles, of whose existence the mind is utterly 
ignorant, which is necessary to effect the required result. But 
it is always the same kind of stimulus, the nervous influence, 
wherever it issues from, which acts upon the cord. Thus, for 
example, when the cord near its upper part is severed from the 
brain by an injury, there is loss of all sensation and voluntary 
motion in the parts supplied by it below the place of lesion, the 
consciousness being no longer in communication with those 
parts ; but irritation of the integument still sends a current as 
before to the spinal cord, and this being distributed by the cor- 
puscles of the grey matter, and descending again by the motor 
nerves, causes involuntary contraction of muscles. This is pro- 
bably the simplest possible example of the phenomenon termed 
by physiologists reiSex nervous action. 
We have ventured on this extremely cursory and general 
