of the tailed catarrhine apes, then of the
tailless apes, and without staying here it irresistibly strides towards
its original goal, and only stops where it is destined to stop. Speaking,
however, not phylogenetically, but ontogenetically, at what point does our
own cell come in contact with the cell that was intended to become an ape,
and that became and remained an ape? If we accept the cell theory in its
latest form, what meaning can there be in the statement of the late Henry
Drummond, that "In a very distant period the progenitors of birds and the
progenitors of men were one and the same"?(39) Would not a very small
quantity of strictly logical thought have cut off _a priori_ the bold
hypothesis that directly or indirectly we descend from a menagerie? Every
man, and consequently all mankind, has accomplished his uninterrupted
embryological development on his own account; no man and no human cell
springs from the womb of an ape or any other animal, but only from the
womb of a human mother, fertilised by a human father. Or do men owe their
being to a miscarriage?

As many streams may flow alongside of each other and through the same
strata, and one ends in a lake while the others flow on and grow larger
and larger, till finally one river attains its highest goal, the sea, so
the cells develop for a time alongside of each other, then some remain
stationary at their points of destination, while others move on farther;
but the cell that has moved forward is as little derived from the
stationary cell as the Indus from the Sarasvati. It is at the points of
destination that the true species digress, and when these points are
reached, the specific development ceases, and there remains only the
possibility of the variety, the origin of which is conditioned by the
multiplicity of individuals; but which must never be confounded with a
true species. Every species represents an act of the will, a thought, and
this thought cannot be shaken from its course, however close temptation
may often come.

With this I believe I have cleared up and refuted one of the objections
that my correspondents made, at any rate to the best of my ability.
Whoever is convinced that each individual, be it fish or bird, springs
from its own cell, knows _ipso facto_ that a human cell, however
undistinguishable it may be to the human eye from the cell of a catarrhine
ape, could never have been the cell of an ape. And what is true
ontogenetically, is of