1866. | On Cell Life. 245 
mucus of the nose. The cells in the medulla oblongata feel it, and 
command the subservient muscles of the thoracic cavity to throw 
off the irritant by a violent expiration, an act which we generally 
call sneezing. Such actions, which can take place without the 
intervention of the superior hemispheres of the brain, have been 
called ‘ reflex actions,’ as distinguished from actions of the will. 
Reflex action is best studied when the cerebral hemispheres 
have been entirely removed. In some animals this is quite possible 
without destroying those parts which enable them to move under 
the influence of external irritation, but the movements then executed 
are observed to differ from those which occur upon similar irritation 
when the cerebral hemispheres have not been removed. The 
various phenomena which have been observed in the actions of 
animals under these conditions, prove that the spinal-cord is a 
centre of animation, and the objections of many philosophers 
against its animation might just as well be urged against that of 
the brain, if they were in reality valid objections. They say that 
each of these phenomena can be explained as simple mechanical 
actions, but we are certain that things have an existence indepen- 
dent of our experience, and that this existence in organic individuals 
is sensation, will—in fact, animation. 
Let us now look at the matter from this point of view, which is 
not the one generally adopted in natural science, but which the 
interpreter of nature may well accept at once, when he has laid 
down his dissecting knife. Thus we shall obtain a new significa- 
tion for some of the phenomena referred to. An uninjured animal— 
a frog, for instance—makes a spring upon irritation of the skin, 
because in the cells of the great brain, consequent upon the 
experiences of the skin and also those of the eye, which are subject 
to the brain, a supposition is founded that a spring protects the 
animal from threatened danger; but, on the contrary, if the 
cerebral hemispheres have been destroyed, the cells of the spinal- 
cord have to take the lead, and because they have not so much 
material of knowledge at their command, seeing that they can 
derive no information from the higher organs of perception, they 
are unable to form the determination and carry it out, of making a 
trial of flight. They are only able to give the order to the nearest 
agent at hand to remove the irritation. This is the foot of the 
animal, which is accordingly raised to the place subjected to irrita- 
tion, for the purpose of removing its cause. Thus, then, the sub- 
ordinate centres of the great cerebro-spinal system become perfectly 
independent if the superior centres are destroyed. In the course of 
normal life, they have, on the other hand, as has been already stated, 
only a relative independence, their commands are only executed 
when counter-mandates are not issued by the higher centres. 
Tn the ordinary course of life a much greater independence apper- 
