beneficial to the life and reproduction of the organism.
Natural selection as here defined means both the increase in the number of
individuals that results after a beneficial mutation has occurred (owing to
the ability of living matter to propagate) and also that this preponderance
of certain kinds of individuals in a population makes some further results
more probable than others. More than this, natural selection can not mean,
if factors are fixed and are not changed by selection.

* * * * *

INDEX

Abnormal abdomen 109
Abraxas 78-81
Allantois 17
Allelomorphs 83-84
Altenburg 112
Amnion 16-17
Andalusian fowl 45, 46
Annelids 22
Antlered wing 111
Apterous wing 11
Arc wing 111
Aristae 104

Bar eye 67, 108, 169
Bateson 18, 34, 36
Beaded wing 11, 115
Beans 147-149, 157
Belgian hare 171
Bent wing 116
Bergson 30, 31
Bildungstrieb 34
Biogenetic law 15, 18, 19, 21
Biometricians 156
Bird 21, 23
Bithorax 65, 112, 113
Black body color 111, 133
Blakeslee 152
Bridges 114, 143, 163
British Association 36
Bruenn 40
Buff eye color 109
Bufon 27

Castle 176-180
Cat 33
Cell 90, 91
Chance variations 37
Chick 16, 17, 20
Chromatin 184
Chromosome group of Drosophila 102
Chromosomes 91, 95, 96, 98, 130, 131, 132
Cleavage 21, 22, 94
Clover butterfly 62
Club wing 69, 70, 108
Colias philodice 62
Color blindness 77, 125
Comb of Drosophila 103
Combs of fowls 33, 54
Comparative anatomy 7, 8, 9, 14
Corn 150, 153, 172
Correns 41
Cosmogonies 27
Cream eye color 163, 164
Crepidula 22
Criss-cross inheritance 78
Crossing over 131-133
Cuenot 178
Curled wing 115
Curved wing 111
Curve of probability 149
Cut wing 11, 104

Dachs legs 112
Dahlgren 62
Darwin 15, 24, 28, 32, 35-37, 64, 145, 146, 152, 154-156
Dendy 188
De Vries 18, 147, 156
Dexter 170
Dichaete 114
Difflugia 184-187
Discontinuous variation 13
Disuse 31
Drosophila ampelophila 10, 12, 13, 48-50, 60, 75, 84, 85, 93, 100, 103,
119, 155, 162, 169
Drosophila repleta 76
Duplication of legs 109
Dwarf 114

East 170, 172
Ebony 50, 55, 56, 115
Egg 91, 94
Elephant 191
Elephants' skulls 188
Elephants' trunks 190
Embryology 13-23
Emerson 172
Environment 27
Eosin eye color 61, 107, 163
Erdmann 183
Evolution Creatrice 30
Evolution--th