of instinctive behaviour, inasmuch as his own motives become co-ordinated and integrated and subject to the best that is in him; while his conduct becomes more delicately adapted to his environment and more nearly productive of the ends that he desires. It is as contributions, be they ever so slight, towards this wider understanding and control of man's nature, that, from the practical and ethical point of view, studies like the present acquire such value as they may possess. FOOTNOTES: [Footnote 246: "La Prohibition de l'inceste et ses origines," _L'Année Sociologique_, I, 1890, 55 ff.] [Footnote 247: _Cp_. Frazer, "Totemism and Exogamy", IV, 100 ff.] [Footnote 248: "History of Human Marriage," 320 ff.] [Footnote 249: A difficulty in connection with Westermarck's theory is concerned with the question as to how an aversion to sexual intercourse between those who have lived from infancy together changed to a similar aversion between blood relatives. How is it, if the original aversion was of the former kind, that it has left but little trace of its existence, while the aversion to marriage between blood relatives, which is supposed to have been derived from it, is grown so strong? It would seem as if the theory would perhaps have to be modified so as to postulate the existence of an original aversion to the marriage of blood relatives, as such; though of course this only opens up the fresh difficulty of accounting for the manner in which such an aversion could arise. We are here faced with the same problem that we have already encountered in the case of the positive aspects of the love impulse between relatives (p. 198 footnote).] [Footnote 250: If this were not the case, we might well ask with other critics why a natural instinct to avoid incestuous relations should need the reinforcement of legal penalties and prohibitions.] [Footnote 251: For a discussion of the question of inbreeding in the present connection, see Frazer, "Totemism and Exogamy", IV. 160 ff.] [Footnote 252: "Inbreeding and Outbreeding", Monographs on Experimental Biology, 1919.]