Now, the exclusion from our definition of direct reference to the conscious aspect must not be taken to imply that instinctive behaviour is a mere matter of unconscious automatism; nor even that it is unprofitable to discuss how much consciousness there may be, of what sort, and how distributed. All that it does imply is, that the amount, nature, and distribution of consciousness cannot well be introduced into a definition the object of which is to help us to distinguish certain observable types of behaviour from others. In a word, the definition given is biological and objective, and is to be accepted or rejected without prejudice to such psychological considerations as those upon which we have now briefly to enter. The first thing we have to decide is how much we are to include, from the psychological standpoint, under instinct. For we may take either a broader or a narrower view of the matter; and which of these we adopt will make much difference in our conclusions. Let us first deal with the narrower. We have said above that what is hereditary in instinctive behaviour is the co-ordination. Now, such co-ordination of 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 only the instinctive co-ordination in itself can be fairly regarded as independent of the stream of experience.