145 
advances with increasing precision. The general assignment of 
digestion to the stomach, of circulation to the heart, and of 
breathing to the lungs, has become very specific ; and far 
minuter knowledge may be regarded as certain. But there is 
much less completeness when we come to ascribe to the brain 
the functions and phenomena of thought. 
19. An organ truly ascertained to be such, shows its relation 
to its functions by its fitness. Thus the orifices and valves 
of the heart are clearly adapted to its office in E8p eciaiiya 9 
the system. This kind of fitness, however, is not to the human 
ascertained in the least, and it is difficult, as Dr. organizatlOD - 
Tyndall allows, to conceive that it ever can be, in respect of the 
brain (p. 121). Though we do not, as in Buffon's time, regard 
the brain as mucous substance of an unimportant character, 
yet there is nothing apparently in its structure to suggest the 
process of thought, as we have seen the contents of the cranium 
lying before us in a basin, — nor even to vindicate altogether the 
Cartesian notion that the pineal gland is the seat of the soul. 
Let us ask how far physiology has proceeded in its analysis, 
and we then may discover how much remains unapproached. 
It would seem fairly certain, for instance, that the cerebral 
organization is enlarged in proportion as intelligence is manifest 
in animals. In accordance, too, with the form of brain, and the 
folds spread over its surface, there probably are different degrees 
of intelligence. There may also appear to be increasing com- 
plexity of organization in the higher animal varieties. 
20. We may readily accept all this, and much more, on the 
testimony of the scientific physiologist, until we have further 
light. The conditions of life are, no doubt, phy- And the 
siologically similar in the cerebral and other organs, physiology of 
mu Ul i . ... ® the brain. 
Xhe blood conveys nutrition, warmth, moisture. 
Let the blood diminish its flow, and the activity of the organ 
is at once affected. On a total withdrawal of blood we should 
expect that the brain would cease to act. A modification even 
of the temperature of the blood has sensible effect on the brain. 
(Some of us are certainly more equal to intellectual exertion 
when we are, as we express it at times, “ warm through.”) 
In addition, too, to the law of general circulation, there is 
some local law of action and repose, in the examination of which, 
however, we seem stopped. It is in this local department we 
find the action of the nerves. While the muscular system acts 
mechanically, the nervous system and the glands, which act 
chemically, we are told, are subject to this local law. The brain 
is no exception to the general law of the circulation of the blood, 
nor to its local adaptations. In all this, however, we have 
arrived at no analysis whatever of the thinker, or the thought; 
