mportant contributions to science, with the exception of a large
separate treatise on the _Oceanic Hydrozoa_ published by the Ray
Society in 1859. There is also announced a formal Biography, prepared
by his son, so that future admirers or students of Huxley's work will
be in an exceptionally favourable position.

LONDON, 1900.

P. CHALMERS MITCHELL.

Leaders in Science

CONTENTS

PAGE
PREFACE iii

CHAPTER I

FROM SCHOOL TO LIFE-WORK 1

Birth--Parentage--School-days--Choice of Medical
Profession--Charing Cross Hospital--End of Medical
Studies--Admission to Naval Medical Service.

CHAPTER II

THE VOYAGE OF THE RATTLESNAKE 13

The Objects of the Voyage--The Route--The Naturalist and the
Surgeon--Collecting and Dredging--Stay in Sydney--Adventures with
the Natives--Comparison with Darwin's Voyage on the _Beagle_.

CHAPTER III

FLOATING CREATURES OF THE SEA 30

The Nature of Floating Life--Memoir on Medusae Accepted by the
Royal Society--Old and New Ideas of the Animal Kingdom--What
Huxley Discovered in Medusae--His Comparison of them with
Vertebrate Embryos

CHAPTER IV

EARLY DAYS IN LONDON 46

Scientific Work as Unattached Ship-Surgeon--Introduction to
London Scientific Society--Translating, Receiving, and
Lecturing--Ascidians--Molluscs and the Archetype--Criticism of
Pre-Darwinian Evolution--Appointment to Geological Survey.

CHAPTER V

CREATURES OF THE PAST 67

Beginning Palaeontological Work--Fossil Amphibia and
Reptilia--Ancestry of Birds--Ancestry of the Horse--Imperfect
European Series Completed by Marsh's American Fossils--Meaning of
Geological Contemporaneity--Uniformitarianism and Catastrophism
Compared with Evolution in Geology--Age of the Earth--Intermediate
and Linear Types.

CHAPTER VI

HUXLEY AND DARWIN 89

Early Ideas on Evolution--Erasmus Darwin--Lamarck--Herbert
Spencer--Difference between Evolution and Natural
Selection--Huxley's Preparation for Evolution--The Novelty of
Natural Selection--The Advantage of Natural Selection as a Working
Hypothesis--Hu