life alike on the general side and the reproductive side, so that their
balanced functions are essential to wholesome and complete existence. In
a rudimentary form these functions may be traced back to our earliest
ancestors who possessed brains. In those times the predominant sense for
arousing the internal mental and emotional faculties was that of smell,
the other senses being gradually evolved subsequently, and it is
significant that the pituitary, one of the chief ductless glands active in
ourselves to-day, was developed out of the nervous centre for smell in
conjunction with the membrane of the mouth. The energies of the whole
organism were set in action through stimuli arising from the outside world
by way of the sense of smell. In process of time the mechanism has become
immensely elaborated, yet its healthy activity is ultimately dependent on
a rich and varied action and reaction with the external world. It is
becoming recognised that the tendency to pluri-glandular insufficiency,
with its resulting lack of organic harmony and equilibrium, can be
counteracted by the physical and psychic stimuli of intimate contacts with
the external world. In this action and reaction, moreover, we cannot
distinguish between sexual ends and general ends. The activities of the
ductless glands and their hormones equally serve both ends in ways that
cannot be distinguished. "The individual metabolism," as a distinguished
authority in this field has expressed it, "is the reproductive
metabolism."[18] Thus the establishment of our complete activities as
human beings in the world is aided by, if not indeed ultimately dependent
upon, a perpetual and many-sided play with our environment.

[18] W. Blair Bell, _The Sex-Complex,_ 1920, p. 108. This book is a
cautious and precise statement of the present state of knowledge on this
subject, although some of the author's psychological deductions must be
treated with circumspection.