ted.
I have called it "the biogenetic law," and will constantly appeal to it
in the course of this study.

It is only in recent times that the two sciences have advanced
sufficiently to reveal the correspondence of the two series of forms.
Aristotle provided a good foundation for embryology, and made some
interesting discoveries, but no progress was made in the science for
2,000 years after him. Then the Reformation brought some liberty of
research, and in the seventeenth century several works were written on
embryology.

For more than a hundred years the science was still hampered by the lack
of good microscopes. It was generally believed that all the organs of
the body existed, packed in a tiny point of space, in the germ. About
the middle of the eighteenth century, Caspar Friedrich Wolff discovered
the true development; but his work was ignored, and it was only fifty
years later that modern embryology began to work on the right line. K.E.
von Baer made it clear that the fertilised ovum divides into a group of
cells, and that the various organs of the body are developed from these
layers of cells, in the way I shall presently describe.

The science of phylogeny, or, as it is popularly called, the evolution
of species, had an equally slow growth. On the ground of the Mosaic
narrative, no less than in view of the actual appearance of the living
world, the great naturalist Linne (1735) set up the dogma of the
unchangeability of species. Even when quite different remains of animals
were discovered by the advancing science of geology, they were forced
into the existing narrow framework of science by Cuvier. Sir Charles
Lyell completely undid the fallacious work of Cuvier, but in the
meantime the zoologists themselves were moving toward the doctrine of
evolution.

Jean Lamarck made the first systematic attempt to expound the theory in
his "Zoological Philosophy" (1809). He suggested that animals modified
their organs by use or disuse, and that the effect of this was
inherited. In the course of time these inherited modifications reached
such a pitch that the organism fell into a new "species." Goethe also
made some remarkable contributions to the science of evolution. But it
was reserved for Charles Darwin to win an enduring place in science for
the theory. "The Origin of Species" (1859) not only sustained it with a
wealth of positive knowledge which Lamarck did not command, but it
provided a more luminous explanation i