170 SECTIONAL ADDRESSES 
the surface of a pond, with the difference that some of the ripples may 
occur spontaneously, whilst others are due to incoming signals. Inter- 
ference figures and nodes of vibration may then be all important. ‘They 
would at least give a basis for the recognition of relations such as those 
of triangularity or squareness without the need for an excitation of specific 
points, and they might be formed with less distortion in a large pond 
than in a small one. 
This does not take us very far: in fact, the major problems of the 
central nervous system are left in greater obscurity than ever. But no 
one can observe these ceaseless electrical pulsations without realising 
that they provide a fresh set of data and may give a fresh outlook on 
the working of the brain. The facts are still too uncertain to be worth 
treating in greater detail. But they accumulate rapidly, and several 
lines of evidence seem to lead in the same direction. For the present 
it is enough to state our problem, that of the organisation of neurones 
into the nervous system. It is still a physiological problem, and I hope 
that a solution will be found on physiological lines. If it cannot be found 
it will be extremely interesting to see where the breakdown occurs, and 
if it can it will be even more interesting to see what light it throws on 
the relation of the nervous system to the mind. 
