Chapter I: Front Matter

LIST OF ILLUSTRATIONS

FRONTISPIECE:--Profile views of the Cranial Dome of
_Pithecanthropus erectus_, the ape-like man from
an ancient river gravel in Java, and of a Greek skull.

FIG. 1.--Frontal view of the Cranial Dome of
_Pithecanthropus_ 16

FIG. 2.--Frontal view of the same Greek skull as that shown
in the frontispiece 16

FIG. 3.--Eoliths, of ‘borer’ shape, from Ightham, Kent 18

FIG. 4.--Eoliths of trinacrial shape, from Ightham, Kent 20

FIG. 5.--Brain casts of four large Mammals 23

FIG. 6.--_Spironema pallidum_, the microbe of Syphilis
discovered by Fritz Schaudinn 37

FIG. 7.--The Canals in Mars 43

FIG. 8.--The Canals in Mars 44

FIG. 9.--Becquerel’s shadow-print obtained by rays from
Uranium Salt 73

FIG. 10.--Diagrams of the visible lines of the Spectrum
given by incandescent Helium and Radium 76

FIG. 11.--The transformation of Radium Emanation into
Helium (spectra) 83

FIG. 12.--Dry-plate photograph of a Nebula and surrounding
stars 90

FIG. 13.--The Freshwater Jelly fish, _Limnocodium_ 97

FIG. 14.--Polyp of _Limnocodium_ 97

FIG. 15.--Sense-organ of _Limnocodium_ 97

FIG. 16.--The Freshwater Jelly-fish of Lake Tanganyika 98

FIG. 17.--Sir Harry Johnston’s specimen of the Okapi 99

FIG. 18.--Bandoliers cut from the striped skin of the Okapi 99

FIG. 19.--Skull of the horned male of the Okapi 100

FIG. 20.--The metamorphosis of the young of the common Eel 101

FIG. 21.--A unicellular parasite of the common Octopus,
producing spermatozoa 102

FIG. 22.--The _Coccidium_, a microscopic parasite of
the Rabbit, producing spermatozoa 102

FIG. 23.--Spermatozoa of a unicellular parasite inhabiting
a Centipede 103

FIG. 24.--The motile fertilizing elements (antherozoids or
spermatozoa) of a peculiar cone-bearing tree, the
_Cycas revoluta_ 104

FIG. 25.--The gigantic extinct Reptile, _Triceratops_ 106

FIG. 26.--A large carnivorous Reptile from the Triassic
rocks of North Russia 107

FIG. 27.--The curious fish _Drepanaspis_, from the
Old Red Sandstone of Germany 107

FIG. 28.--The oldest Fossil Fish known 108

FIG. 29.--The skull and lower jaw of the ancestral Elephant,
_Palæomastodon_, from Egypt 109

FIG. 30.--The latest discovered skull of _Palæomastodon_ 110

FIG. 31.--Skulls of _Meritherium_, an Elephant ancestor,
from the Upper Eocene of Egypt 111

FIG. 32.--The nodules on the roots of bean-plants and the
nitrogen-fixing microbe, _Bacillus radicola_,
which produces them 114

FIG. 33.--The continuity of the protoplasm of vegetable
cells 116

FIG. 34.--Diagram of the structures present in a typical
organic ‘cell’ 117

FIG. 35.--The Number of the Chromosomes 119

FIG. 36.--The Number of the Chromosomes 120

FIGS. 37 to 42.--Phagocytes engulphing disease germs--drawn
by Metschnikoff 136-7

FIG. 43.--A Phagocyte containing three Spirilla, the germs
of relapsing fever, which it has engulphed 137

FIG. 44.--The life-history of the Malaria Parasite 142

FIG. 45.--The first blood-cell parasite described, the
_Lankesterella_ of Frog’s blood 144

FIG. 46.--Various kinds of Trypanosomes 145

FIG. 47.--The Laboratory of the Marine Biological Association
on the Citadel Hill, Plymouth 155

FIG. 48.--The Tsetze fly, _Glossina morsitans_ 172

FIG. 49.--The Trypanosome of Frog’s blood 173

FIG. 50.--The Trypanosome which causes the Sleeping
Sickness 176

FIG. 51.--The Trypanosome of the disease called “Dourine” 177

FIGS. 52 to 56.--Stages in the growth and multiplication of
a Trypanosome which lives for part of its life in
the blood of the little owl, _Athene noctua_,
and for the other part in the gut of the common
Gnat (_Culex_) 180-3