l alimentary canal.

But at that low plane the functions of life are few and simple. This bit
of vitalised inorganic has no sex, and because of that it cannot love.
Reproduction is growth. When it grows over-large it splits in half, and
where was one cell there are two. Nor can the parent cell be called
_mother_ or _father_: and for that matter, the parent cell cannot be
determined. The original cell split into two cells; one has as much
claim to parenthood as the other.

It lives dimly, to be sure, this mote of life and light; but before it
is a vast evolution, Dane, on the pinnacle of which are to be found men
and women, Hester Stebbins, my mother, you!

A step higher we find the cell cluster, and with it begins that
differentiation which has continued to this day and which still
continues. Simplicity has yielded to complexity and a new epoch of life
been inaugurated. The outer cells of the cluster are more exposed to
environmental forces than are the inner cells; they cohere more
tenaciously and a rudimentary skin is formed. Through the pores of this
skin food is absorbed, and in these food-absorbing pores is foreshadowed
the mouth. Division of labour has set in, and groups of cells specialise
in the performance of functions. Thus, a cell group forms the skinny
covering of the cluster, another cell group the mouth. And likewise,
internally, the stomach, a sac for the reception and digestion of food,
takes shape; and the juices of the body begin to circulate with greater
definiteness, breaking channels in their passage and keeping those
channels open. And, as the generations pass, still more groups of cells
segregate themselves from the mass, and the heart, the lungs, the
liver, and other internal organs are formed. The jelly-like organism
develops a bony structure, muscles by which to move itself, and a
nervous system--

Be not bored, Dane, and be not offended. These are our ancestors, and
their history is our history. Remember that as surely as we one day
swung down out of the trees and walked upright, just so surely, on a far
earlier day, did we crawl up out of the sea and achieve our first
adventure on land.

But to be brief. In the course of specialisation of function, as I have
outlined, just as other organs arose, so arose sex-differentiation.
Previous to that time there was no sex. A single organism realised all
potentialities, fulfilled all functions. Male and female, the creative
factors, were incohere