Abraxas grossulariata, 99
"Acquired" characters, 14
Adaptation, 143
Agouti mice, 50
Albino mice, 50
Albinos, nature of, 53
Amauris, 144
Analysis of types, 156
Ancestral Heredity, Law of, 13
Andalusian fowls, 70
Axil colour in sweet peas, 93
Bateson, W., 14, 29, 55, 116, 132, 141
Biffen, R. H., 157
Blue Andalusian fowls, 71
Brachydactyly, 171
Bryony, 120
Bush sweet peas, 63
Castle, 132
Colour, nature of, in flowers, 48
Colour-blindness, 117
Coupling of characters in gametes, 93
"Cupid" sweet peas, 62
Currant moth, 99
Discontinuity in variation, 14
Dominant characters, 18
Doncaster, L., 99
Drinkwater, H., 172
Dutch rabbits, 60
Factor, definition of, 31
Factors, interaction of, 42
Fertilisation, 3
Fertilisation, self- and cross-, 163
Fixation of varieties, 153
Fluctuations, 138
Hæmophilia, 176
Hardy, G. H., 147
Heterozygote, definition of, 28
Heterozygote, of intermediate form, 68
Himalayan rabbits, 60
Homostyle primulas, 56
Homozygote, definition of, 28
Hooded sweet peas, 89
Horses, bay and chestnut in, 167
Johannsen, W., 160
Lop-eared rabbits, 132
Mental characters, 180
Mice, inheritance of coat colour in, 50
Mimicry, 143
Mirabilis, 151
Morgan, T. H., 116
Mulattos, 129
Pararge egeria, 132
Parkinson, J., 122
Pea comb, 33
Peas, coloured flowers in, 24
Peas, tall and dwarf, 18
Pigeons, 86
Pin-eye in primulas, 55
Pisum, 17
Pollen, 3
Pollen of sweet peas, 92
Pomace fly, 115
Population, inheritance of characters in a, 147
Presence and Absence theory, 35
Pure lines, 162
Purity of gametes, 24
Purity of type, 155
Ratios, Mendelian—
3 : 1, 20
9 : 3 : 4, 51
9 : 7, 49
Ray, John, 143
Recessive characters, 19
Repulsion between factors, 90
in rabbits, 59
in sweet peas, 62
in fowls, 65
in pigeons, 65
Rose comb, 33
Seeds, nature of, 4
Segregation, 22
Selection, 162
Sheep, horns in, 76
Single comb, 32
Species, nature of, 150
Species, origin of, 11
Speckled wood butterfly, 132
Spermatozoa, 3
Sports, 147
Staples-Browne, R., 66
Sterility, 151
Sterility in sweet peas, 93
Stocks, double, 122
Stocks, hoariness in, 54
history of, 82
inheritance of hood in, 89
inheritance of size in, 62
Unit-character, definition of, 31
Walnut comb, 33
Weismann, A., 13
Wheat, beard in, 74
experiments with, 157
White, dominant in poultry, 72
Wilson, J., 168
Yellow mice, 119
Zygotes, nature of, 5
Notes
[2] It has been found convenient to denote the various generations resulting from a cross by the signs F1, F2, F3, etc. F1 on this system denotes the first filial generation, F2 the second filial generation produced by two parents belonging to the F1 generation, and so on.
[3] Hurst's original cross was between a Belgian hare and an albina Angora, which turned out to be a masked Dutch.
[4] The Spot is an almost white bird, the colour being confined to the tail and the characteristic spot on the head.
[5] The reader who searches florists' catalogues for these varieties will probably experience disappointment. The sweet pea has been much "improved" in the past few years, and it is unlikely that the modern seedsman would list such unfashionable forms.
[6] It is to be understood that wherever a given factor is present the plant may be homozygous or heterozygous for it without alteration in its colour.
[7] It should be mentioned that as the shape of the pollen coat, like that of the seed coat, is a maternal character, all the grains of any given plant are either long or else round. The two kinds do not occur together on the same plant.
[8] For the most recent discussion of this peculiar case the reader is referred to Professor Castle's paper in Science, December 16, 1910.
[9] Paradisus Terrestris, London, 1629, p. 261.