106 INSTINCTIVE BEHAVIOUR 
acts we see are often the joint products of heredity and in- 
dividual acquisition, the inherited co-ordination having been 
supplemented or otherwise altered through experience. 
Even in the case of the very first exhibition of such a deferred 
instinct as the moor-hen’s dive, although that organized 
sequence of acts which constituted the behaviour as a whole 
had never before occurred, although there was no gradual 
learning how to dip beneath the surface, and to swim under 
water, still many of the constituent acts had been often 
repeated ; experience had already been gained of much of the 
detail then for the first time combined in an instinctive 
sequence. So that if we distinguish between instinct as con- 
genital and habit as acquired, we must not lose sight of the 
fact that there is continual interaction, in a great number of 
cases, between instinct and habit, and that the first performance 
of a deferred instinct may be carried out in close and in- 
extricable association with the habits which, at the period of 
life in question, have already been acquired. Instinct supplies 
an outline sketch of behaviour, to which experience adds colour 
and shading. Which predominates in the finished picture 
depends on the status of the animal. In the lower and less 
intelligent types the outline stands out clearly, there being but 
little shading to divert our attention from the clear firm lines 
inscribed by heredity ; but in the higher and more intelligent 
animals, the deft pencil of experience has added so much detail 
and has interwoven with the fainter outline so many new and 
skilfully introduced touches, that the original sketch is scarcely 
distinguishable unless we have carefully watched from the 
beginning the gradual development of the picture. 
V.—TuHE Evo.uTion oF INSTINCTIVE BEHAVIOUR 
It may be assumed that the fact of evolution is generally 
admitted. ‘The question of its method is, however, still open 
to discussion. It is possible that, as some biologists contend, 
there is an inherent tendency in organic beings to evolve in 
