ILLUSTRATIONS 



PLATES 



FACING PAGE 



I-I V. Microsporogenesis 156 



V. Development of Pollen-grain 164 



VI. Pollination and subsequent Phenomena 166 



VII. Growth of the Pollen-tube 168 



VIII-XI. Spermatogenesis 170 



XII-XIII. Macrosporogenesis 178 



XIV. Germination of Macrospore 182 



XV. Female Prothallium 1S4 



XVI-XVIII. Oogenesis 186 



XIX-XXI. Fertilization 192 



XXII-XXIII. Development of Proembryo 198 



XXIV. Abnormalities 202 



XXV. Map of Slate River, Colorado 438 



XXVI. Map of Slate River, Colorado 438 



XXVII-XXXIV. Thirteen photographs show^ing beaver dams, 



houses, etc., in Slate River Valley, Colorado.. 438 



TEXT FIGURES 



PAGE 



I. Fore and hind wings of honey bee (drone) 214 



2-5. Fore wing of honeybee (drone) 215 



6-7. Hind wing of honey bee (drone) 216 



8. Hind wings of honey bee (drone) 217 



9. Fore and hind wings of honey bee (worker) 217 



10. Fore wings of honey bee (drones) 219 



11. Fore wing of honey bee (drone) 222 



1 2-20. Frequency polygons of variation in wings of honey 



bees 223-330 



21. Part of costal margin of hind wing of honey bee 



much magnified, to show hooks 231 



22-33. Frequency polygons of variation in costal hooks of 



wings of honeybees 232-239 



34. Fore and hind wings of male black ant 245 



35-44. Frequency polygons of variation in costal hooks of 



wings of black ants 246-252 



45. Wing of ant showing venation 255 



46-48. Diagrams showing variation in elytral and pro- 

 thoracic pattern of the convergent lady-bird 258-272 



49. Frequency polygon of variation in prothoracic pat- 

 tern in the convergent lady-bird 273 



