Daphnia, changed by environment, 216 Dasypus, polyembryony, 42 Dianthoecia, fixed and variable species, 25 Disease-resistance, 87 Division, power of, a fundamental attribute of living things, 38 Genetics of, 46,50 Dogger Bank, large varieties on, 125 Dogs, hybrid, 241 Dominance, nature of, 95 Dominants, origin of new, 88,90,95 Double monsters, 42 Draba, experiments with, 242 Drosophila, 91 Payne's experiments on, 228
Earthworm, regeneration, 77 Elephant, tusk segmented, 38 Entelechy, 80 Environmental treatment, effects of, 188 et seq. Enzymes and genetic factors, 86 Epilepsy, inheritance of traumatic, 197 Equidae, sterility of hybrid, 241 Erophila, experiments with, 242 species, 249 Exacum, right and left, 57 Euphonia elegantissima, local forms, 120 Eupithecia rectangulata, melanic form, 137
Factors, new, 88 loss of, 96 Factorial representation of varieties, 158,165 Falcons, geographical races, 147 Fasciation, 49 Ferments, Boyle on, 54 Finger-prints of twins, 44 Fixity and Variability in species, 25 Flax, climatic experiments, 197 Fowl, Silky, 84 Leghorn, 85,90 Dominant white, 94 Wyandotte, 97 Rumpless, 46 Foxes, incompatibility with dogs, 241 Free-martin, 44 Fringillidae, sterility of hybrid, 241 Fundulus, cyclopian, 50
Gallus, invariability of wild species, 13 and origin of poultry, 90,97 Genitalia, a basis for classification in insects, 13 Gentians, climatic experiments, 197 Geometrical structure and differentiation, 54,56 Geometrical distinction between germ-cells and somatic cells, 58 Gladiolus, right and left, 57 Gnophus obscurata, protective colouring, 141 Goldfinch, geographical races, 147 Gonioctena variabilis, variation in sexes of, 121 Gouldian Finch, polymorphism, 148,149 Gracilaria stigmatella, experiments on, 193 Grantia, large varieties of, 125 Ground-Squirrels, local forms of, 132 Grouse, red, variation, 29 Guillemot, Ringed, 150 Guinea-pig, Brown-Séquard's experiments on, 198 Gynandromorphs, 45
Heliconius erato, forms of, 122,164 Helix lapicida, local variation of, 126 striata, 127 Heripensis, 127 Caespitum, 127 trochoides, 127 nemoralis and hortensis, 128 Helminthophila, geographical races of, 157 Hemerophila abruptaria, melanic, 142 Hepialus humuli, in Shetland, 119 Heterostyle plants, 236 Hieracium, 9 Himantopus, 234 Homoeosis, 68 Hybernia progemmaria, 139 Hybrids, sterility of, 233 et seq.