the diploma of a descent from the ape, and would prove to them that
the genius of a Shakespeare or a Goethe is merely a distillation from
a drop of primitive mucus." Another well-known theologian protested
against "the horrible idea that the greatest of men, Luther and
Christ, were descended from a mere globule of protoplasm."
Nevertheless, not a single informed and impartial scientist doubts the
fact that these greatest men were, like all other men--and all other
vertebrates--developed from an impregnated ovum, and that this simple
nucleated globule of protoplasm has the same chemical constitution in
all the mammals.


CHAPTER 1.7. CONCEPTION.

The recognition of the fact that every man begins his individual
existence as a simple cell is the solid foundation of all research
into the genesis of man. From this fact we are forced, in virtue of
our biogenetic law, to draw the weighty phylogenetic conclusion that
the earliest ancestors of the human race were also unicellular
organisms; and among these protozoa we may single out the vague form
of the amoeba as particularly important (cf. Chapter 1.6). That these
unicellular ancestral forms did once exist follows directly from the
phenomena which we perceive every day in the fertilised ovum. The
development of the multicellular organism from the ovum, and the
formation of the germinal layers and the tissues, follow the same laws
in man and all the higher animals. It will, therefore, be our next
task to consider more closely the impregnated ovum and the process of
conception which produces it.

The process of impregnation or sexual conception is one of those