358 ORIGIN AND CIRCULATION OF THE NERVOUS INFLUENCE. 
our consciousness, and this should be a powerful reason for 
doubting its truth. When I prick my finger, I am not con- 
scious of any impression being transmitted to the brain ; on 
the contrary, I perceive the impression in the finger, and only 
there. Why, then, should we suppose that we are conscious 
only of impressions that are conveyed to the brain ? It is true 
that any obstruction in the nerves connecting the external 
organs with the brain destroys sensation or motion. But 
this only shows that, for these functions to be performed, it 
is necessary that the electric circuit should be uninterrupted. 
The mind, however, is as likely to perceive any modification 
of that circuit at the point where it occurs, as at the distant 
central organ. And in the same way, motion may arise from 
some change effected at the extremities of the nerves, and not 
from an influence transmitted from the brain. 
Regarding those operations which are considered as mental, 
I w r ould merely hazard a conjecture — namely, that the large 
development of the cerebrum should not be considered as a 
central organ, but as a development of peripheral nerves, re- 
ceiving electricity from the capillaries of the blood-vessels of 
the brain, and that these nerves have their centre in the com- 
missures. This organ, which thus consists entirely of nerves 
and blood-vessels, may be, in accordance with general opinion, 
the seat of mental operations. 
If it were established that there is a constant circulation of 
the nervous fluid, such as has been described, it would render 
our conceptions of the nervous system as clear as those we 
possess of the circulation of the blood. The principle which 
governs it is the same as that of the galvanic battery, or a 
more apt illustration w 7 ould be the electric telegraph, wfith its 
electricity conveyed by the positive and returned by the nega- 
tive wire; and to carry out the comparison, the different 
nervous centres may be considered as so many telegraphic 
stations. There is this difference, however, that, instead of 
successive sparks of electricity, w 7 e have a sustained and con- 
tinuous current, and consequently a provision in the circula- 
tion of the blood for keeping up a supply of the chemical 
ingredients necessary to maintain the stream. 
If it w 7 ere established that the circulation of nervous fluid 
is kept up in the manner described, it would improve our 
knowdedge of the circulation of the blood, by showing a pur* 
pose effected by it even more important than the nourishment 
of the tissues ; and w 7 e should then clearly understand the 
use of the oxygenation of the blood by respiration, to be the 
restoration to that fluid of the power of imparting electricity. 
—* Lancet . 
