Index. 



335 



Sexual differences in lucifer, 

 184 



notedelphys, 177 

 onitis, 193 

 orcnestia, 187 

 ostracoda, 175 

 papilio turnus, 237 

 paradise birds, 237 

 phasmidse, 236 

 pollicipes, 181 

 rotifera, 171 

 saphirrina, 176 

 scalpellum, 181 

 shrike, 237 

 social insects, 237 

 tanais, 188 

 Sexual dimorphism, 187 



" reproduction, 11,17, 143, 



289 



" selection, 169, 212 

 Sheep, hybrid, 129, 131 



" modification of male, 



222 



variation in, 297 

 Siebold on parthenogenesis, 55 

 Simpson on hermaphroditism, 



109 



" on latent transmis- 

 sion, 106 

 Sitana, 198 

 Smerinthus, 59 

 Solenobia, 61 



Sow, parthenogenesis in, 67 

 Spurred hen, 210 

 Spathogaster, 



Species of large genera, 153 

 Speculations on heredity, 18 

 Spermatozoa, discovery of, 21 

 Spencer, definition of life, 38 

 " on Irish elk, 287 



Spike horn deer, 298 

 Staphylinidse, 194 

 Strongylocentrotus, 66 

 Sweet pea, hybrid, 132 



Tanais, 188 



Theory of heredity, 319, 16 

 Tiger, hybrid, 130 

 Transmission without fusion, 



131 

 Turkey, variation of, 150 



Uhler on polymorphism, 238 



Variability, how caused, 82 



" of offspring of hy- 

 brids, 122 



" of sexual charac- 

 ters, 154 



Variations, 13, 17 

 causes of, 140, 275, 293 

 caused by climate, 142 



' ' change of food, 142 



crossing, 119 

 " excess of food, 143 

 correllated, 157 

 of exceptional parts, 153 

 of homologous parts, 158 

 of hybrids, 18 

 law of equable, 154 

 of male butterflies, 195 

 of organisms produced sex- 

 ually, 143, 249 

 parallel or analogous, 302 

 and sexual reproduction, 249 

 of species of large genera, 153 

 summary of chapter on, 161 

 Viragines, 105 

 Von Baer, 22 



