100 INSTINCTIVE BEHAVIOUR 
movements into a finished and appropriate act is due to a 
nicely graded distribution of efferent nerve-waves to the several 
muscles concerned, so that these muscles may be caused to 
contract in due order, and each to just the right extent. But 
efferent nerve-waves as such, and their mode of distribution by 
the nerve-centres, are in all probability unconscious, while the 
contraction of the muscles is a purely organic matter. If, 
therefore, we narrow our conception of instinct so as to include 
only the co-ordinated act by itself, excluding all reference both 
to the stimuli which are its antecedents, and to the effects in 
consciousness which its performance may produce ; and if the 
data for consciousness are in all cases supplied through 
afferent channels ; then there seems to be no escape from the 
conclusion that instinctive behaviour as such may be, and 
probably is, altogether outside the individual consciousness. 
It should be noted, however, that on this view it is the co- 
ordination in itself that is, if not unconscious, at any rate 
independent of the stream of experience. 
Now, in the first place it is convenient so far to broaden our 
conception as to include under the head of instinctive behaviour, 
in its conscious aspect, not only the co-ordinated act but the 
data which its performance affords to consciousness. It may 
indeed seem that we are here trying to draw a distinction 
where no real difference exists. The physiological distinction 
is, however, not only clear and undeniable, but quite easily 
understood. For the sake of illustration let us take the case 
of an intentional action, such as glancing up from the words 
we are reading to the clock. Efferent waves course along 
several motor nerves to the six muscles by which each eye is 
moved, and to the muscles of accommodation within the eye. 
These muscles are called into duly co-ordinated activity, by 
which our vision is focussed upon the clock-face. This is one 
part of the physiological procedure—that by which the intended 
result is attained. But there is a second part readily dis- 
tinguishable from the former. As the eyes move, afferent 
messages course inwards from the muscles or the eye-sockets and 
their neighbourhood ; and it is these incoming waves which 
