ABSTRACT
The sexual responses of lower mammals are determined mainly by physiological changes the manifestations of which are gross enough to be plainly perceptible to human observation. The male lower mammal with functional gonads is in a physiological state that can be readily reflected into overt sexual behaviour, the appropriate stimulus for the full display of his mating reactions being a female in heat. His heterosexual responses will therefore be limited by factors operating in the females he encounters, and they in turn will seek his advances only while they are in the phase of desire—œstrus. The varied forms which associations of breeding individuals may take among the lower mammals are conditioned by the interaction of such physiological mechanisms.
