of poppy in, 364

French archeologists, leading dis-
coveries with regard to pre-
historic man made by, 371,

372

Frogs, common, eggs of, 209, 212
growth from the egg, 213-215
English species, 216

European species, 216, 219

green tree-frog of Riviera, 49, 50,
52, 55

method of catching prey, 219
Furniture worm, 351, 352

Gases-

oxygen, action of ordinary, 259
experiments as to possible use
by athletes, 260-263
Fleuss diving apparatus and
diluted supply of, 263-265
ozone, destructive powers of, 253
discoveries of Andrews and Tait
with regard to, 252
experiments of Schönbein with
regard to, 251, 252
methods of producing, 252, 253,
258
nature of, 252

proportion of, to fresh country
or sea-coast air, 253
result of experiments with regard
to, 259
signification of name, 252
therapeutic value and uses of,
258,259

use in water-purification, 256,
258

Geology, Darwin's discoveries in,

24

table showing history of man in

Western Europe, 384 bis

Germany, custom of eating preserves
with meat in, prevalent, 358
predominance of scientific know-
ledge in, 8

eel by, 70-72
Green-flies, 322

Green tree-frog, 49, 50
Griffin, heraldic, 116

Guinea-pig, native home and original
introduction of, 360, 361

various names given to, 360, 361

Halley, Edmund, astronomical dis-
coveries of, 226

date of death, 230
foundation of Royal Society Club
by, 230

law of movement of comets dis-
covered by, 226, 230

Milton and, scholars of St. Paul's
School, 228, 229

Newton and, friendship of, 230
Halley's comet, 226, 230
Hansen, leprosy-bacillus discovered
by, 240

Hay fever, individual susceptibility
to, 102, 104, 105
probable cause, 105

similarity between vegetable
poisonings and, 105

Heart, action of nervous system upon,
in man and higher animals,
151

muscular contraction,

150, 151

cause of,

rate of beat in higher and lower
animals, 152-154

in human species, 151, 152
significance of its beat, 147, 148
valves, action of, 149
Hedge-sparrow, 267

Henslow, Professor, Darwin as in-
fluenced by, 36

Herschel, Sir John, definition of
word "species" by, 14,

15

Hertwig, Professor, German repre-
sentative at Darwin Cen-
tenary Celebration, 33

carried by, 3

with regard to use of oxygen
gas, 260-265

Hipparion horse, 84, 85, 86
Hippopotamus age, 380, 386
Histology, origin of 176
Hook, Robert, Micrographia by, 173,
288, 289

Hooker, Sir Joseph, Darwin and
Wallace papers communi-
cated to Linnean Society by,
12, 13

Hop-blight, causes of, 317-319
prevention of, 318, 319

Hop-louse, 317

Horses-continued

selective breeding of, from time of
cave-men onward, 82, 83
Southern or Arabian breeds of,
of "pre-orbital

presence
cup" in, 86, 87

House-sparrows, 266

growers of, 321

cultivation of, 315-316

curing of, 320

English growers as affected by
American and German hop-
plantations, 320, 321

uses made of, 315

Horses, absence from

continent in

American
fifteenth

with regard to fecundity of
plant lice, 338

Hydra, heraldic, derivation of, 116
Hyracotherium horse, 84

Kew Gardens, beauty and interest of,
302, 303

specimens of Rhus toxicodendron
at, 93, 94

Koch (Berlin), cholera-bacillus dis-
covered by, 240

tubercle-bacillus

240

Ladybird, 325

discovered by,

Lamarck, inferiority of scientific
methods, as compared with
Darwin, 19-22, 26

Philosophical Zoology by, 20
Lankester, Sir Ray, address by,
Darwin Centenary Celebra-
tion at Cambridge, 33-37
Leprosy, bacillus of, discovery by
Hansen, 240
"Leptocephali," discovery of, 70-72
Life, protoplasm the seat of, 182-184,
328

Herbert Spencer's definition of, 183,
184

Light, rate at which it travels, 221
Locusts, winged serpents and, pro-
bable connection between,
124-125
Lunatics, distinctions between feeble-
minded and, 274-276
laws relating to feeble-minded and,
need for improvement in, 275
Lyell, Sir Charles, Darwin and
Wallace papers communi-
cated to Linnean Society by,
12, 13

Malaria, comparative death-rate from,
in Panama Canal zone, 2-4
measures adopted in Cuba and
Panama for prevention of,
2, 3

Mammoth age, 380, 386

Man, sleep of, compared with repose
or quiescence of other living
things, 159-161

Mankind, congenital defects in,
causes of, 273

Mental defect, 274
Metchnikoff, Professor, discoveries
with regard to use and value
of "phagocytes," 39
experiment by, in connection with
cholera-bacillus, 241