DR. PHILIP ON THE POWERS OF LIFE. 
371 
volition which excites them. They are quiescent till this act takes place. Hence it 
is that respiration ceases on the removal of the medulla oblongata, because by the 
removal of this part of the brain the power of sensation in all parts below the head 
and consequently of volition, as far as relates to those parts, is destroyed. Hence 
also the fact, above referred to, that the vital has a remote dependence on the sen- 
sitive system for the maintenance of its organs. If the muscles of respiration were 
not in the strictest sense muscles of voluntary motion, our powers of volition would 
in an essential respect be imperfect ; for the due regulation of their action is essential 
in the formation of articulate sounds, the chief means by which our sensorial powers 
are enabled to influence those of other sentient beings. 
In the papers on the Nature of Sleep and Death, published in the Philosophical Trans- 
actions for 1833 and 1834, I have pointed out how much the functions of the more 
perfect animal are influenced by this peculiarity of respiration, the only vital func- 
tion, properly so called, in which the sensorial power cooperates ; a circumstance 
which more generally perhaps than any other, which is equally of a local nature, 
influences the phenomena both of health and disease. In this function therefore we 
find a powerful bond of connexion between the sensitive and vital systems, and one, 
as appears from the papers just referred to, of the most extensive operation. 
SUCH are the means by which the frame of the more perfect animal is formed into 
a whole, and the function of sympathy and its other more complicated functions 
above enumerated effected. A powerful connexion is established among all parts of 
each of the systems into which the functions arrange themselves, depending on each 
being regulated by a leading power which influences every part of the system to which 
it belongs, and in its turn is influenced by every part of it : and these systems them- 
selves are intimately related in consequence of the nervous, the leading power in the 
vital system, by means of the control which the sensorial power exercises over it, 
being employed in the accomplishment of many of the sensitive functions, and the 
sensorial power, the leading power in the sensitive system, in one of the most im- 
portant of the vital functions ; by both systems not only depending for the main- 
tenance of their organs on the same powers, but more or less directly on each other; 
by the powers common to both systems being under the influence of the leading prin- 
ciples of both ; and by all affections of whatever part, whether original or sympa- 
thetic, necessarily influencing both its sensitive and vital nerves, and consequently 
the central organs of the system to which they belong. 
FROM the whole of the facts referred to in the preceding paper, the great outline 
of the laws which regulate the functions of the more perfect animal is derived. The 
parts of which it consists, from the complicated nature of the subject, being very 
numerous, it is necessary, in order to place it in a clear point of view, concisely to 
recapitulate them; and as in the preceding paper, I commenced with the more 
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