VSKY.) 272

14. TRANSVERSE SECTION OF THE WORM _NAIS_. (SEMPER.) 280

15. THE FIVE PRIMARY STAGES OF ONTOGENY. (HAECKEL.) 292

FORM AND FUNCTION

CHAPTER I

THE BEGINNINGS OF COMPARATIVE ANATOMY

The first name of which the history of anatomy keeps record is that of
Alcmaeon, a contemporary of Pythagoras (6th century B.C.). His
interests appear to have been rather physiological than anatomical. He
traced the chief nerves of sense to the brain, which he considered to
be the seat of the soul, and he made some good guesses at the
mechanism of the organs of special sense. He showed that, contrary to
the received opinion, the seminal fluid did not originate in the
spinal cord. Two comparisons are recorded of his, one that puberty is
the equivalent of the flowering time in plants, the other that milk is
the equivalent of white of egg.[1] Both show his bias towards looking
at the functional side of living things. The latter comparison
reappears in Aristotle.

A century later Diogenes of Apollonia gave a description of the venous
system. He too placed the seat of sensation in the brain. He assumed a
vital air in all living things, being in this influenced by Anaximenes
whose primitive matter was infinite air. In following out this thought
he tried to prove that both fishes and oysters have the power of
breathing.[2]

A more strictly morphological note is struck by a curious saying of
Empedocles (4th century B.C.), that "hair and foliage and the thick
plumage of birds are one."[3]

In the collected writings of Hippocrates and his school, the _Corpus
Hippocraticum_, of which no part is later than the end of the 5th
century, there are recorded many anatomical facts. The author of the
treatise "On the Muscles" knew, for instance, that the spinal marrow
is different from ordinary marrow and has membranes continuous with
those of the brain. Embryos of seven days (!) have all the parts of
the body plainly visible. Work on comparative embryology is contained
in the treatise "On the Development of the Child."[4]

The author of the treatise "On the Joints," which Littre calls "the
great surgical monument of antiquity," is to be credited with the
first systematic attempt at comparative anatomy, for he compared the
human skeleton with that of other Vertebrates.

Aristotle (384-322 B.C.)[5] may fairly be said to be the founder of
comparative anatomy, not because he was specially interested in
proble