Form and Function | Page 2

HILAIRE 52
VI. THE FOLLOWERS OF ETIENNE GEOFFROY ST HILAIRE 79
VII. THE GERMAN TRANSCENDENTALISTS 89
VIII. TRANSCENDENTAL ANATOMY IN ENGLAND--RICHARD
OWEN 102
IX. KARL ERNST VON BAER 113
X. THE EMBRYOLOGICAL CRITERION 133
XI. THE CELL-THEORY 169

XII. THE CLOSE OF THE PRE-EVOLUTIONARY PERIOD 190
XIII. THE RELATION OF LAMARCK AND DARWIN TO
MORPHOLOGY 213
XIV. ERNST HAECKEL AND CARL GEGENBAUR 246
XV. EARLY THEORIES ON THE ORIGIN OF VERTEBRATES 268
XVI. THE GERM-LAYERS AND EVOLUTION 288
XVII. THE ORGANISM AS AN HISTORICAL BEING 302
XVIII. THE BEGINNINGS OF CAUSAL MORPHOLOGY 314
XIX. SAMUEL BUTLER AND THE MEMORY THEORIES OF
HEREDITY 335
XX. THE CLASSICAL TRADITION IN MODERN MORPHOLOGY
345
INDEX 365

ILLUSTRATIONS
FIG. PAGE
1. HYOID ARCH OF THE CONGER. (ORIGINAL.) 58
2. "VERTEBRA" OF A PLEURONECTID. (GEOFFROY.) 61
3. ABDOMINAL SEGMENT OF THE LOBSTER. (GEOFFROY.) 63
4. IDEAL TYPICAL VERTEBRA. (OWEN.) 102
5. NATURAL TYPICAL VERTEBRA. (OWEN.) 103
6. THE ARCHETYPE OF THE VERTEBRATE SKELETON.

(OWEN.) 105
7. IDEAL TRANSVERSE SECTION OF A VERTEBRATE
EMBRYO. (VON BAER.) 119
8. GILL-SLITS OF THE PIG EMBRYO. (RATHKE.) 134
9. MECKEL'S CARTILAGE AND EAR-OSSICLES IN EMBRYO OF
PIG. (REICHERT.) 145
10. CRANIAL VERTEBRÆ AND VISCERAL ARCHES IN
EMBRYO OF PIG. (REICHERT.) 148
11. EMBRYONIC CRANIUM OF THE ADDER. (RATHKE.) 152
12. TRANSVERSE SECTION OF CHICK EMBRYO. (REMAK.) 211
13. DEVELOPMENT OF THE ASCIDIAN LARVA
(KOWALEVSKY.) 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 Littré 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
problems of "pure morphology," but because he described the structure
of many animals and classified them in a scientific way. We shall
discuss here the morphological ideas which occur in his writings upon
animals--in the Historia Animialium, the De Partibus Animalium, and
the De Generatione Animalium.

The Historia Animalium is a most comprehensive work, in some ways
the finest text-book of Zoology ever written. Certainly few modern
text-books take such a broad and sane view of living creatures.
Aristotle never forgets that form and structure are but one of the many
properties of living things; he takes quite as much interest in their
behaviour, their ecology, distribution, comparative physiology. He
takes a special interest in the comparative physiology of reproduction.
The Historia Animalium contains a description of the form and
structure of man and of as many animals as Aristotle was acquainted
with--and he was acquainted with an astonishingly large number. The
later De Partibus Animalium is a treatise on the causes of the form and
structure of animals. Owing to the importance which Aristotle