its historical growth. This task will, however, not detain us long.
The study of man's evolution is one of the latest branches of natural
science, whether you consider the embryological or the phylogenetic
section of it.

Apart from the few germs of our science which we find in classical
antiquity, and which we shall notice presently, we may say that it
takes its definite rise, as a science, in the year 1759, when one of
the greatest German scientists, Caspar Friedrich Wolff, published his
Theoria generationis. That was the foundation-stone of the science of
animal embryology. It was not until fifty years later, in 1809, that
Jean Lamarck published his Philosophie Zoologique--the first effort to
provide a base for the theory of evolution; and it was another
half-century before Darwin's work appeared (in 1859), which we may
regard as the first scientific attainment of this aim. But before we
go further into this solid establishment of evolution, we must cast a
brief glance at that famous philosopher and scientist of antiquity,
who stood alone in this, as in many other branches of science, for
more than 2000 years: the "father of Natural History," Aristotle.

The extant scientific works of Aristotle deal with many different
sides of biological research; the most comprehensive of them is his
famous History of Animals. But not less interesting is the smaller
work, On the Generation of Animals (Peri zoon geneseos). This work
treats especially of embryonic development, and it is of great
interest as being the earliest of its kind and the only one that has
come down to us in any completeness from classical antiquity.

Aristotle studied embryological questions in various classes of
animals, and among the lower groups he learned many most remarkable