vi CONTENTS 



PAGE 



24. Thermonastic curvatures ..... .112 



25. Hydronastic movements . . 116 



26. Conjoint effects . . .119 



27. (continued) ... . .123 



28. The mechanics of nutation movements .... ... 128 



29. variation movements . . . -134 



PART V. THE INFLUENCE OF THE EXTERNAL CONDITIONS UPON 

 AITIONASTIC CURVATURE 



30. Special and general actions . .140 



PART VI. DEHISCENCE AND DISPERSAL MOVEMENTS 



31. Special and general . ... ... . 146 



CHAPTER III 



TROPIC MOVEMENTS 



PART I. INTRODUCTORY 



32. General ..... . 154 



33. (continued). . . -157 



PART II. THE VARIOUS FORMS OF TROPIC CURVATURE 



34. Geotropism - 162 



35. Methods of investigating geotropism 166 



36. Heliotropism ... 170 



37. The heliotropic action of rays of different wave-length 174 



38. Thermotropism ... 176 



39. Chemotropism and osmotropism ... 178 



40. Hydrotropism .... . . 182 



41. Mechanotropism ... . 184 



42. Galvanotropism .... .... . 1 88 



43. Autotropism and somatotropism . 189 



PART III. THE CONDITIONS FOR AND CHARACTER OF TROPIC STIMULATION 



44. Instances of the separate localization of perception and response . . .192 



45. Instances of autogenic and of aitiogenic changes of irritability . . . 202 



46. Changes of irritable tone (continued) 206 



47. Minimal stimuli and the latent periods of induction and reaction . . . 209 



48. The relation between the intensity of stimulus and the resultant excitation . 212 



49. The conditions for stimulation and its progress . . . . . .216 



50. Perception and response 219 



51. Instances of specific tropic irritability . . , . . 221 



PART IV. THE MECHANISM OF TROPIC MOVEMENT 



52. The progress and mode of movement ... . 230 



53. The mechanism of curvature ... . 238 



54. The internal causes of movement . . 244 



