There is, however, another way in which analogous propensities may be ingrained in the mental constitution, not as residual vestiges of old instincts, but as congenital rudiments fostered by new habits. It is a well-known and familiar fact that the frequent repetition of intelligent accommodation in certain definite lines begets habits, which so far simulate instincts as to be commonly described in popular speech as instinctive. Professor Wundt indeed places them in the category of “acquired instincts”--a usage which we regard as unsatisfactory, seeing that it tends to mask the distinction between the congenital and acquired factors in behaviour, and seeing that we have the well-defined term “habits” for acts rendered to a large extent automatic through repetition. Lamarckian thinkers regard habit as the mother of instinct, assuming that the acquired automatism of one generation may be transmitted to become congenital in the succeeding generation. This conclusion we provisionally reject, regarding the basal assumption as at present unproven. But though we cannot accept the view that habit is the mother of instinct, we regard it as not improbable that habit may be the nurse of congenital propensities. Remembering that similar habits are acquired by animals of the same species throughout a series of succeeding generations, and assuming that congenital variations are constantly occurring in many directions, it seems probable that some of these variations will be coincident in direction with the acquired habits. Thus would arise a congenital propensity to perform the habitual acts; and should they be of sufficient importance in the conduct of life to be subject to the action of natural selection, those animals in which such propensities were congenital would survive, whereas those in which no such propensities existed would be eliminated. It is unnecessary, however, to elaborate this conception further, since it is in line with that already discussed in considering the influence of intelligence in fostering a diversion of instinct under changing circumstances. Then we were considering how habit may lead to a congenital change in an old instinct; here we are dealing with the development of a new propensity. Sufficient has now been said to illustrate some of the ways in which instinct and intelligence interact in the evolution of behaviour. Such interaction is further exemplified in the social life of animals, which will be dealt with in the next chapter. CHAPTER V _SOCIAL BEHAVIOUR_ I.--IMITATION