viii CONTENTS 



PAGE 



PART II. THE PRODUCTION OF LIGHT 

 84. Instances and causes of luminosity 382 



PART III. THE PRODUCTION OF ELECTRICAL TENSIONS IN THE PLANT 



85. The origin and detection of electromotive changes 388 



86. The influence of external agencies upon the production of electricity . . 394 



CHAPTER VI 



THE SOURCES AND TRANSFORMATIONS OF ENERGY IN THE PLANT 



87. General view 399 



88. The forms of physical energy used by plants 402 



89. Chemical energy 405 



90. Special cases 409 



APPENDIX 415 



INDEX 423 



