Table of Contents 



PAGES 



worms. i8. The Chemical Sense in Annelids. 19. The 

 Chemical Sense in MoUusks. 20. The Chemical Sense in 

 Echinoderms. 21. The Chemical Sense in Crustacea. 

 22. The Chemical Sense in Arachnida. 23. The Chemical 

 Sense in Insects. 24. How Ants Find Food. 25. The 

 Use of Smell in Path Finding by Ants. 26. How Ants 

 "Recognize" Nest Mates. 27. How Bees Are Attracted 

 to Flowers. 28. How Bees Find the Hive. 29. How 

 Bees "Recognize" Nest Mates. 30. The Chemical Sense 

 in Vertebrates. 



CHAPTER VI 

 Sensory Discrimination : Hearing . . . . " . 1 16-134 



Q31. Hearing in Lower Invertebrates. 32. Hearing in 

 Crustacea. 33. Hearing in Spiders. 34. Hearing in In- 

 sects. 35. Hearing in Fishes. 36. Hearing in Amphibia. 

 37. Hearing in Higher Vertebrates. 



CHAPTER VII 



Sensory Discrimination: Vision 135-171 



O i^. Change of Light Intensity as a Stimulus. ^39. The 

 Continuous Action of Light : Photokinesis. ^40. The 

 Problem of Visual Qualities : Invertebrates. 41. The Prob- 

 lem of Visual Qualities: Amphioxus and Fish. 42. The 

 Problem of Visual Qualities : Reptiles and Amphibia. 43. The 

 Problem of Visual Qualities ; Birds. 44. The Problem of 

 Visual Qualities : Mammals. 



CHAPTER VIII 



Spatially Determined Reactions and Space Perception . 172-214 

 <?45. Classes of Spatially Determined Reactions. 46. Class 

 I: Reactions to a Single Localized Stimulus. 47. Class 

 II: Orienting Reactions: Possible Modes of Producing 

 Them. 48. Orientation to Gravity: Protozoa.© 49. Ori- 

 entation to Gravity: Coelenterates. 50. Orientation to 

 Gravity: Planarians. $1. Orientation to Gravity: An- 

 nelids. 52. Orientation to Gravity: Mollusks. 53. Ori- 

 entation to Gravity: Echinoderms. S4- Orientation to 



