among, 105, 108; influence on
soil, 91; man's struggle with,
146

Ape, 277, 288f.

Aphids, 108

Apple, 168

Apricot, 167

Apteryx, 276, 292

Argon, 11, 15, 23

Ark, Noah's, 271f., 275f.
Arsenic, 186, 230

Artichoke, Jerusalem, 168
Artifacts, primitive, 178ff.
Asiatics, climatic adaptation of,

63ff.; racial characters of,
377 ff.

Aspen, 51
Ass, 106, 151f., 155, 277
Association,

between different

forms of life, 93ff.; in strug-
gle for existence, 105ff.; social
life of insects, 145f. See also
Mutual aid; Institutions; So-
ciety.

Astronomy, 3ff.

Badger, 115, 139

duction of, 87; temperature
and, 51

Balance of nature. See Nature;

Life.

Balsam, 132

Banana, 167, 169f.

Barberry, 103, 233f.

Barium, 8

Barley, 253

Barnacles, 133

Barracuda, 52

Bass, 99, 102
Beans, soil fertility and, 90
Bear, 114, 115, 123

Beaver, 115, 120

Bedbug, 132

Bees, 105, 165, 359f.

Beet, 139

Beet sugar, 172, 253
Beetles, damage to pines, 132;
eaten by birds, 137; Japanese,
129f., 142; ladybird, 131; po-
tato, 128, 316; varieties on St.
Helena, 289

Atoms, 10ff., 30

Auk, 119

Aurochs, 153f.

Baboon, 288

Bacteria, beginning of life and,
32f.; chemistry of, 90; classi-
fied by foods, 88; discovery of,
207 ff.; in digestive system,
91f.; in early explanations of
disease, 206; killed by sunlight,
53, 101; nature and distribution
of, 45f.; nitrogen-fixing, 33;
pathogenic, 210f.; possible uti-
lization of, 176f.; respond to
stimuli, 55f.; size and repro-

Beriberi, 240
Beryllium, II
Birds, destruction of, 118f.,
140f.; domesticated, 162ff.;
food habits of, 104, 134ff.; list
of extinct, 147; protection of,
144f.; reptiles and, 275; serv-
ices to man, 133ff.
Biological analogies, 451f.
Biometrics, 320f.
Birth control, 263, 265, 424f.
Birth rate among women in in-
dustry, 412f.; declining, 415ff.;
differential, 416f., 419ff.; in
United States, 264f. See also
Sterility.

of, II

Yeast.