CONSCIOUSNESS AND SENSATION. 105 
elements is very necessary to secure that end. 
Thus it will be seen that the doctrine of brain- 
action which is here proposed by no means 
separates altogether the character of the mind 
from dependence on that of the brain. There are 
three elements on which the character of the brain 
as affecting the mind may be safely presumed to 
depend, viz. the intensity and ease of action pos- 
sible to individual brain-elements, the total amount 
of those elements, and, lastly, but possibly, most 
important of all, the freedom and perfection of 
communication of those elements one with an- 
other. It may well be supposed that this last 
requisite is more liable to be deficient in large 
brains, as the distances are greater and the ele- 
ments to be joined together more numerous in 
them. 
In the structure of the brain there is the closest 
affinity to the structure of the rest of the nervous 
system, and its corpuscles are elements plainly 
comparable with the living parts or protoplasm- 
derivatives of other textures, and there is ground 
to presume that in like manner the impressed 
condition of nerve-corpuscles, whether in the brain 
or elsewhere, and of nerve-fibres is analogous to 
the contraction of muscular fibres and of amzboid 
corpuscles: the peculiarity of those of the hemis- 
