psychologic
development of the normal sexual emotions. Nearly every writer seems
either to take for granted that he and his readers are so familiar
with all the facts of normal sex psychology that any detailed
statement is altogether uncalled for, or else he is content to write
a few introductory phrases, mostly made up from anatomic, philosophic
and historical work.

"Yet it is unreasonable to take normal phenomena for granted here as
in any other region of medicine. A knowledge of such phenomena is as
necessary here as physiology is to pathology or anatomy to surgery.
So far from the facts of normal sex development, sex emotions and sex
needs being uniform and constant, as is assumed by those who consider
their discussion unnecessary, the range of variation within fairly
normal limits is immense, and it is impossible to meet with two
individuals whose records are nearly identical.

"There are two fundamental reasons why the endeavor should be made to
obtain a broad basis of clear information on the subject. In the
first place, the normal phenomena give the key to the abnormal, and
the majority of sexual perversions, including even those that are
most repulsive, are but exaggerations of instincts and emotions that
are germinal in normal human beings. In the second place, what is
normal cannot be determined until the sexual life of a large number
of healthy individuals is known, and until the limits of normal
sexuality are known the physician is not in a position to lay down
any reasonable rules of sexual hygiene."

Although very short, the analysis of the sex passions in adults by
Herbert Spencer[4] in a part of one section in his "Principles of
Psychology," is one of the best. Bain[5] devotes one chapter to the
Tender Emotion which he makes include Sex-love, the parental
feelings, the benevolent affection, gratitude, sorrow, admiration and
esteem. A very few pages are given to sex-love proper. Very
suggestive paragraphs bearing either directly or indirectly upon the
subject are to be found in the works of such writers as Moll, Sergi,
Mantegazza, James, Janet, Delboeuf, Fere, Boveri, Kiernan, Hartmann,
Dessoir, Fincke and others. There is a vast amount of literature upon
the pathological phases of the subject which is to be considered in
another chapter.

The analyses thus far given by scientists are limited to the emotion
as it is manifested in the adult. A few writers have referred to it
in dealing with the psy