tea or dissipation. All these guide and
limit the education of the two sexes very much alike. The principle
or condition peculiar to the female sex is the management of the
catamenial function, which, from the age of fourteen to nineteen,
includes the building of the reproductive apparatus. This imposes upon
women, and especially upon the young woman, a great care, a
corresponding duty, and compensating privileges. There is only a
feeble counterpart to it in the male organization; and, in his moral
constitution, there cannot be found the fine instincts and quick
perceptions that have their root in this mechanism, and correlate its
functions. This lends to her development and to all her work a
rhythmical or periodical order, which must be recognized and obeyed.
"In this recognition of the chronometry of organic process, there is
unquestionably great promise for the future; for it is plain that the
observance of time in the motions of organic molecules is as certain
and universal, if not as exact, as that of the heavenly bodies."[24]
Periodicity characterizes the female organization, and developes
feminine force. Persistence characterizes the male organization, and
develops masculine force. Education will draw the best out of each by
adjusting its methods to the periodicity of one and the persistence of
the other.

Before going farther, it is essential to acquire a definite notion of
what is meant, or, at least, of what we mean in this discussion, by
the term co-education. Following its etymology, _con-educare_, it
signifies to draw out together, or to unite in education; and this
union refers to the time and place, rather than to the methods and
kinds of education. In this sense any school or college may utilize
its buildings, apparatus, and instructors to give appropriate
education to the two sexes as well as to different ages of the same
sex. This is juxtaposition in education. When the Massachusetts
Institute of Technology teaches one class of young men chemistry, and
another class engineering, in the same building and at the same time,
it co-educates those two classes. In this sense it is possible that
many advantages might be obtained from the co-education of the sexes,
that would more than counterbalance the evils of crowding large
numbers of them together. This sort of co-education does not exclude
appropriate classification, nor compel the two sexes to follow the
same methods or the same regimen.

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