SECTION 1—PHYSIOLOGY. 
THE ACTIVITY OF NERVE CELLS 
ADDRESS BY 
PROF. E. D. ADRIAN, F.RS., 
PRESIDENT OF THE SECTION. 
SINcE the biologist seeks to understand life, he cannot be accused of 
lack of courage. But he can find out a great deal without approaching 
too near the central problem. He can find out how the living cell develops 
and how it behaves; he can follow many of the physical and chemical 
changes which take place in it, and could follow more if cells were not so 
inconveniently small. The immediate problems of the physiologist may 
be still further removed from the problem of life. They may deal, for 
instance, with the mechanics of the vascular system or with the physical 
chemistry of blood pigments. But most of us aim at explaining the 
working of the body in terms of its constituent cells, and feel that this 
is a reasonable aim even though we must take the cell for granted. Is 
it a reasonable aim when we are dealing with the working of the nervous 
system? ‘That is the problem which I shall discuss this morning. 
The nervous system is responsible for the behaviour of the organism 
as a whole: in fact, it makes the organism. A frog is killed when its 
brain and spinal cord are destroyed : its heart still beats and its muscles 
can still be made to contract, all the cells of its body but those of the 
brain and cord are as fully alive as they were before; but the frog is 
dead and has become a bundle of living tissues with nothing to weld 
them into a living animal. This integrative action of the nervous system, 
to use Sherrington’s classical phrase, we may be able to explain in terms 
of the reactions of the constituent nerve cells. We can at least discuss 
the point as physiologists. But the human organism includes a mind 
as well as a body. It may be best to follow Pawlow and to see how 
far we can go without bringing in the mind, but if the reactions of our 
nerve cells are to explain thought as well as action we must face the 
prospect of becoming psychologists and metaphysicians as well. 
Fortunately we need not yet go to such extremes. There are problems 
enough on the physiological plane, and they are made all the more 
interesting by this hint of mystery in the background. 
_ The nervous system, the brain, spinal cord and peripheral nerves, is 
made up of a large number of living cells which grow, maintain them- 
selves by the metabolism of food-stuffs, and carry out all the complex 
reactions of living protoplasm. In this there are enough problems for 
anyone ; but we are concerned not with the general properties of living 
cells but with those special properties which enable the cells of the 
