On the whole, it may be said that in the usual life of man odors play a not inconsiderable part and raise problems which are not without interest, but that their demonstrable part in actual sexual selection--whether in preferential mating or in assortative mating--is comparatively small. FOOTNOTES: [85] Moll has a passage on this subject, _Untersuchungen über die Libido Sexualis_. Bd. I, pp. 376-381. HEARING. I. The Physiological Basis of Rhythm--Rhythm as a Physiological Stimulus--The Intimate Relation of Rhythm to Movement--The Physiological Influence of Music on Muscular Action, Circulation, Respiration, etc.--The Place of Music in Sexual Selection among the Lower Animals--Its Comparatively Small Place in Courtship among Mammals--The Larynx and Voice in Man--The Significance of the Pubertal Changes--Ancient Beliefs Concerning the Influence of Music in Morals, Education, and Medicine--Its Therapeutic Uses--Significance of the Romantic Interest in Music at Puberty--Men Comparatively Insusceptible to the Specifically Sexual Influence of Music--Rarity of Sexual Perversions on the Basis of the Sense of Hearing--The Part of Music in Primitive Human Courtship--Women Notably Susceptible to the Specifically Sexual Influence of Music and the Voice. The sense of rhythm--on which it may be said that the sensory exciting effects of hearing, including music, finally rest--may probably be regarded as a fundamental quality of neuro-muscular tissue. Not only are the chief physiological functions of the body, like the circulation and the respiration, definitely rhythmical, but our senses insist on imparting a rhythmic grouping even to an absolutely uniform succession of sensations. It seems probable, although this view is still liable to be disputed, that this rhythm is the result of kinæsthetic sensations,--sensations arising from movement or tension started reflexly in the muscles by the external stimuli,--impressing themselves on the sensations that are thus grouped.[86] We may thus say, with Wilks, that music appears to have had its origin in muscular action.[87] Whatever its exact origin may be, rhythm is certainly very deeply impressed on our organisms. The result is that, whatever lends itself to the neuro-muscular rhythmical tendency of our organisms, whatever tends still further to heighten and develop that rhythmical tendency, exerts upon us a very decidedly stimulating and exciting influence.