420 



INDEX 



Polymorphism, definition, 1 1 



— , examples, 94 and foil. 



— , in colour, 282 



— , proof that variation not due to 

 environment, 127 



— , wild and domesticated races com- 

 pared, 190 



Polyommatus, change in population, 213 



Polyploidy, 23, 24 



Ponera, age of species, 132 



Pontania, experiments on, 41, 75 



Population-analysis, definition, 15 



— , examples, 15 



Population, Natural, definition, 10, 59, 60 



Population, optimum density. 359 



Populations, change in composition of, 

 Birds, 215 



— , change in composition of, Crustacea, 



— , change in composition of, Diabrotica, 



209 

 — , change in composition of, Lepi- 



doptera, 213-15 

 — , change in composition of, Mollusca, 



2I 5 

 — , fluctuations in, 359 



Porter, polymorphism in Sceliphron, 103 

 Portunus, correlation of characters, 1 63 

 Poulton, colour-changes in insects, 281 

 — , local variation in sex-ratio of 



Hypolimnas, 124 

 — , mimicry in Hawaiian wasps, 259 

 Poulton and Saunders, experiments on 



pupae of Vanessa, 203 

 Prashad, parallel adaptation, 326 

 Pre-adaptation, 301 

 Preferential mating, see Selective mating 

 Promptoff, variation in song of 



Chaffinch, 121 

 Protective coloration, D'Arcy Thomp- 

 son's view, 364 

 Protective resemblance, 232 



, incidence in different groups, 



234 



, in Mantis, 202 



, McAtee's observations, 249-51 



, Morton Jones's observations, 



247-49 



, also see Mimicry 



Protozoa, clone-formation, 72 

 ■ — , Dauermodifikationen, 35 

 — , physiological races, 119 

 Psammochares, specific differences, 277, 



278 

 Psammocharidae, specific characters, 



276, 300 

 Pseudagenia, characters, 266, 278 

 Pseudonestor, young taught what to eat, 



254 

 Psycho-biology, 344 

 Psychodidae, species-recognition, 148 



Punnett, magnitude of steps in evolu- 

 tion in mimicry, 255 

 Pure lines, 72 



•, experiments on, 191 



Purpose in evolution, 374-75 

 Putorius, winter moult, 241-42 

 Pyrausta, death-rates in nature, 193 

 - — , voltinism, 53, 144 

 Pyrenestes, characters of, 289 



Rabbit, colonies of, 117 



— , excessively curved incisors, 336 



— , large and small races, 329 



Races, stability of, 70 



Racovitza, characters of cave animals, 



269 

 — , eyes of cave animals, 271 

 Radiation, natural, 30 

 Radium, effect on mutation-rate, 29- 



3° 

 Radl, disbelief in Natural Selection 



theory, 186 



Ramsbottom, ' taxonomic ' species, 62 



Rana, breeding season of races, 145 



Random elimination, 193-96, 222 



Random mating, 148, 225-27 



Raphicervus, lack of geographical races, 

 106 



Rassenkreise, 59, 70 



Rats, experiments on, 28, 40-41 



— , local variation, 70 



— , selection of hooded pattern, 192 



Recapitulation, 326, 328 



Reciprocal dependence of parts, 168 



Recombination, 24 



— , role in evolution of domesticated 

 races, 189-91 



— , also see Permutations 



Recombinations, spread of particular 

 types, 226 



Rectigradations, 324 



Regan, characters of Salmon and 

 Salmon parr, 287 



■ — , characters of 2j>arces, 287 



Regeneration, as process by which 

 stable form is reached and main- 

 tained, 302 



Reichert, variation in non-living sub- 

 stances, 3 



Reighard, significance of colour in 

 coral fishes, 240-41 



Reindeer, white form attacked by 

 parasites, 242 



Reinhard, behaviour of Philanthus, 354 



Relation (type of correlation), 161 



Rensch, colonies of land snails, 96 



— , correlation between environmental 

 factors and structural divergence, 



3.17 

 — , environmental trends, 44 



