It is possible that we must take into account here a biological factor, such as we have found involved in other forms of sadism and masochism. In this connection a lady writes to me: "With regard to the theory which connects the desire for whipping with the way in which animals make love, where blows or pressure on the hindquarters are almost a necessary preliminary to pleasure, have you ever noticed the way in which stags behave? Their does seem as timid as the males are excitable, and the blows inflicted on them by the horns of their mates to reduce them to submission must be, I should think, an exact equivalent to being beaten with a stick." It is remarkable that in some cases the whip would even appear to have a psychic influence in producing sexual excitement in animals accustomed to its application as a stimulant to action. Thus, Professor Cornevin, of Lyons, describes the case of a Hungarian stallion, otherwise quite potent, in whom erection could only be produced in the presence of a mare in heat when a whip was cracked near him, and occasionally applied gently to his legs. (Cornevin, _Archives d'Anthropologie Criminelle_, January, 1896.) Here, undoubtedly, we have a definite anatomical and physiological relationship which often serves as a starting-point for the turning of the sexual feelings in this direction, and will sometimes support the perversion when it has otherwise arisen. But this relationship, even if we regard it as a fairly frequent channel by which sexual emotion is aroused, will not suffice to account for most, or even many, of the cases in which whipping exerts a sexual fascination. In many, if not most, cases it is found that the idea of whipping asserts its sexual significance quite apart from any personal experience, even in persons who have never been whipped;[116] not seldom also in persons who have been whipped and who feel nothing but repugnance for the actual performance, attractive as it may be in imagination.