The emotion of love between the sexes has as yet received no thorough scientific treatment. No writer so far as I can find has treated it from a genetic standpoint. The literature upon the subject is therefore meager. Most psychologists have been very sparing of details where it is concerned, and one might mention certain voluminous treatises which contain no mention of it. Is this through exaggerated delicacy? Or is it because the authors think that their place has been usurped by the novelists who have so obstinately confined themselves to the study of this passion?