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 * . .188 



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 



