Part 1

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OUR PRESENT KNOWLEDGE OF THE DESCENT OF MAN

ERNST HAECKEL (JENA)

WITH NOTES AND BIOGRAPHICAL SKETCHES

HANS GADOW, F.R.S. (CAMBRIDGE)

LONDON ADAM AND CHARLES BLACK 1898

CONTENTS

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INTRODUCTORY 1

COMPARATIVE ANATOMY 8

PALÆONTOLOGY 20

OTHER EVIDENCE 42

STAGES RECAPITULATED 47

BIOGRAPHICAL SKETCHES:

LAMARCK, SAINT-HILAIRE, CUVIER, BAER, MUELLER, VIRCHOW, COPE, KOELLIKER, GEGENBAUR, HAECKEL 80

THEORY OF CELLS 115

FACTORS OF EVOLUTION 117

GEOLOGICAL TIME AND EVOLUTION 135

NOTE

The address I delivered on August 26 at the Fourth International Congress of Zoology at Cambridge, 'On our Present Knowledge of the Descent of Man,' has, I find, from the high significance of the theme and the general importance of the questions connected with it, excited much interest, and has led to requests for its publication. Hence this volume, edited by my friend Dr. H. Gadow, my pupil in earlier days, who has not only revised the text, but has also enriched it by many valuable additions and notes.

ERNST HAECKEL.

Jena, December, 1898.

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At the end of the nineteenth century, the age of 'natural science,' the department of knowledge that has made most progress is zoology. From zoology has arisen the study of transformism, which now dominates the whole of biology. Lamarck laid its foundation in 1809, and forty years ago Charles Darwin obtained for it a recognition which is now universal. It is not my task to repeat the well-known principles of Darwinism. I am not concerned to explain the scientific value of the whole theory of descent. The whole of our biological study is pervaded by it. No general problem in zoology and botany, in anatomy and physiology, can be discussed without the question arising, How has this problem originated? What are the real causes of its development?

See note, p. 80.

This question was almost unknown seventy years ago, when Charles Darwin, the great reformer of biology, began his academical career at Cambridge as a student of theology. In the same year, 1828, Carl Ernst von Baer published in Germany his classical work on the embryology of animals, the first successful attempt to elucidate by 'observation and reflection' the mysterious origin of the animal body from the egg, and to explain in every respect the 'history of the growing individuality.' Darwin at that time had no knowledge of this great advance, and he could not divine that forty years later embryology would be one of the strongest supports of his own life's work--of that very theory of transformism which, founded by Lamarck in the year of Darwin's birth, was accepted with enthusiasm by Charles's grandfather Erasmus. There is no doubt that of all the celebrated naturalists of the nineteenth century Darwin achieved the greatest success, and we should be justified in designating the last forty years as the Age of Darwin.

See note, p. 89.

In searching for the causes of this unexampled success, we must clearly separate three sets of considerations: first, the comprehensive reform of Lamarck's transformism, and its firm establishment by the many arguments drawn from modern biology; secondly, the construction of the new theory of selection, as established by Darwin, and independently by Alfred Wallace (a theory called Darwinism in the proper sense); thirdly, the deduction of anthropogeny, that most important conclusion of the theory of descent, the value of which far surpasses all the other truths in evolution.