LIST OF ILLUSTRATIONS 



1. Protective Coloration of the Rocky Mountain White-tailed 



Ptarmigan ......... 29 



2. The Sussex Man 34 



3. Positive Heliotropism of a Marine Worm .... 47 



4. Comparison of the Embryos of Man and Other Vertebrates 50 



5. Venus' Fly-trap 53 



6. Contest between Ant-bear and Puma 76 



7. Horror and Agony 124 



8. Athlete making a Record Broad Jump 126 



9. Finish of One-half Mile Intercollegiate Race . . . 127 



10. Athlete breaking the Record for Shot Put . . . . 128 



11. Anger in Male Gorilla 129 



12. Exhausted Suffragist 130 



13. Cat Terrified by Dog 131 



14. Violent Effort .133 



15. Exhaustion .......... 134 



16. Tigress and Cubs at Rest 135 



17. Composure . 137 



18. Photomicrographs showing Effects of Acute and of Chronic 



Fright on the Brain-cells of a Rabbit . . ,. 139 



19. Case of Exophthalmic Goiter 142 



20. Tracing showing Effect of Fear on Adrenal Output of a 



Cat 146 



21. Photomicrographs showing the Effect of Fright on the 



Brain-cells of a Rabbit 149 



22. Photomicrographs showing the Effect of Fright on the Ad- 



renals of a Rabbit 150 



23. Photomicrographs showing the Effect of Fright on the Liver 



of a Rabbit 151 



24. Photomicrographs showing the Effect of Insomnia on the 



Brain-cells of a Rabbit 166 



25. Photomicrographs showing the Effect of Insomnia on the 



Adrenals of a Rabbit 167 



26. Photomicrographs showing the Effect of Insomnia on the 



Liver of a Rabbit . . . . ' 168 



27. Photomicrographs showing the Effect of Exertion on the 



Brain-cells of a Cat 169 



xiii 



