It is in this sense that we are here concerned with what we may perhaps best call the play-function of sex.[19] [19] The term seems to have been devised by Professor Maurice Parmelee, _Personality and Conduct_, 1918, pp.

104, 107, 113.

But it is understood by Parmelee in a much vaguer and more extended sense than I have used it.
As thus understood, the play-function of sex is at once in an inseparable way both physical and psychic.

It stimulates to wholesome activity all the complex and inter-related systems of the organism.

At the same time it satisfies the most profound emotional impulses, controlling in harmonious poise the various mental instincts.