100 Dr. A. P. W. Philip on the 
by destroying a certain part of the spinal marrow, while they, 
as may be ascertained by the application of stimuli, perfectly 
retain their vigour, and the sensation which excites the wish to 
inspire, though as in the last case useless, remains unimpaired. 
If even any two of these powers be destroyed, they leave the one 
which remains entire. The destruction of the muscles of 
respiration, and of the nervous influence which excites them, 
does not destroy the sensation by which we will to inspire; nor 
does the destruction of this sensation, together with that of the 
nervous influence, at all impair the power of the muscles of re- 
spiration, provided they are not exhausted by the means em- 
ployed for these purposes. And we may destroy the sensation 
in question, and the power of the muscles, without impairing the 
nervous influence which excites them. So far from correct is the 
position of M. le Gallois, that the powers on which all the motions 
of inspiration depend reside in the medulla oblongata. 
Much has been written by Whytt, and other physiologists, re- 
specting the cause of the first inspiration. I cannot help think- 
ing that the difficulty vanishes when we regard the muscles of 
inspiration as merely muscles of voluntary motion. The young 
animal throws them into action to remove a painful sensation oc- 
casioned by the want of that change in the blood which is pro- 
duced by the influence of the air in the lungs ; a process necessary 
to its existence as soon asits connexion with the mother ceases, 
and which can only be effected by expanding the chest, and thus 
receiving air into the lungs. It seems to be expanded for the 
first time precisely for the same reason that the foetus changes 
its position for the first time by acting with the muscles of the 
trunk and limbs. In both cases it endeavours to remove an uneasy 
sensation, and nature has given it the power to remove it by calling 
into action certain muscles subjected to the will. The first act of 
deglutition, if it does not occur in the foetal state, appears to be an 
act of precisely the same nature with the first inspiration. In both 
eases a certain set of muscles of voluntary motion is thrown into 
action to satisfy a craving which had no existence in that state. 
Tt may be objected to this view of the cause of the first inspi- 
ration, that the animal often breathes before a ligature is thrown | 
