INDEX 



409 



Dominance, evolution of, 227-29 



— , shown only in external characters, 



228 

 Doncaster, spread of melanic Lepido- 



ptera, 213 

 Dragonflies, polymorphism, 282 

 — , seasonal occurrence, 144 

 — , see also Lestes 



Driesch, theory of development, 168 

 Drosophila, continuous variation with 

 discontinuous genetic basis, 87 

 crossing geographical strains, 26 

 diminished mutant, 24 

 effects of X-rays on, 29 

 experiments on selection of, 204-5 

 heterozygosity of wild, 26 

 mating habits and isolation of 



species, 150 

 multiple effects of single genes, 



170 

 mutants showing dominance in 



external characters only, 228 

 mutation in eye-colours, 28 

 mutation-rate, 220 

 mutations induced by high tem- 

 perature, 29 

 mutations resembling generic and 

 family characters of other groups, 



175 

 non-heritable variants, 20 



occurrence of mutants in nature, 



223 

 reared in the dark, 44 

 species hybrids, 155 

 tarsal comb of male proved to be 



unnecessary for mating, 296 

 tetraploids, 24 

 trisomatic intersexes, 23 

 viability of mutants, 219, 222 

 Drosophila obscura, intersterile races, 



157 

 Duerden, callosities of ostrich, 43 



— , lack of geographical races in 



Testudo, 108 



Dufour, ' lock and key ' theory, 152 



Dunbar, orthogenesis, 325 



Duncan, crossing geographical strains 



of Drosophila, 26 



Duncker, local races, 69 



Diirken, correlation, 161 



— , experiments on Pieris brassicae, 37 



Dwarfing, see Stunting 



Dwight, insular forms of birds, 139 



Dytiscidae, variation in sculpture, 93 



Earthworms, ' superpapillate ' forms, 



289 

 Echinoids, possible permutations of 



characters in, 60 

 Ecospecies, 59, 72 



Ecotype, 59, 72 



Ectodermal derivatives, variation in, 5 



Edelsten, adaptive differences in 



JVonagria, 290 

 Edentata, convergence with the 



Cetacea, 356 

 Edwards, Chironomids differing in 

 habits more than in structure, 

 1 22 

 — , correlation of male and female 



genitalia, 153 

 — , correlation of mouth-parts and 

 feeding habits in the Blepharo- 

 ceridae, 300 

 Eel, lack of geographical races, 185 

 — , migration of races, 146 

 — , xanthochroism, 93 

 Eggers, specific differences in copula- 



tory styles of Planarians, 297 

 Eimer, orthogenesis, 324, 326, 328 

 Eisentraut, changed habits of Lacerta, 



54 

 — , influence of diet on colour of 



Hemidactylus, 79 

 Ekman, lacustrine Limnocalanus, 45 

 Elan vital, 340 

 Elaps, significance of bright colours, 



243-44 

 Elateridae, grooves for reception of 



antennae, 309 

 ' Elementary species,' 58 

 Elephas, size of tusks, 331 

 Elk, Irish, size of antlers, 331 

 Elton, change of habits in Bubalis 



coffer, 54 

 — , colour-phases of Arctic Fox, 94 

 — , death-rates in mammals, 194 

 — , effects of epidemics on populations, 



320 

 — , fluctuations of environment, 355 

 — , interbreeding of polymorphic 



species, 149 

 — , optimum population density, 359 

 — , polymorphism, 282 

 ■ — , selection of environment by animal, 



354 



— , survival of mutants without selec- 

 tion, 319, 320 and foil. 



Eltringham, dimorphism in Acraea, 

 1 1 



— , Geometrid larva acquiring dis- 

 tasteful properties from food, 

 247 



— , gregarious larvae of Acraea, 246 



■ — , intrageneric mimicry in Heliconius 

 and the Pieridae, 256 



— , leathery integument of Lepido- 

 ptera with warning colours, 245 



— , polymorphism in Heliconius, 102 



— , polymorphism in mimetic Lepido- 

 ptera, 262 



