CONTENTS 



CHAPTER VII 



r 

 Action op Light trpoisr Protoplasm 



PAGE 



§ 1. The Application and Measurement of Light .... 154 



§ 2. The Chemical Action of Light upon Non-living Substances 161 



1. The Synthetic Effects of Light 162 



2. Analytic Effect of Light ... . . 163 



3. Substitution Effects of Light . . . 164 



4. The Tsomerismic and Polymerismic Changes produced by Light 164 

 § 3. The Effect of Light upon the General Functions of Organisms . 166 



1. Effect of Light upon Metabolism ...... 166 



a. The Thermic Effect of Light on Metabolism . 166 



b. The Chemical Effect of Light on Metabolism . . 170 



2. Vital Limits of Light Action on Protoplasm . . 171 

 8. Effect of Light upon the Movement of Protoplasm . 175 



u. Effect of Low Intensity of Light on Movement — Dark- 

 rigor . . 175 



b. Effect of High Intensity of Light on Movement — 



Light-rigor ... .... 178 



§4. Control of the Direction of Locomotion by Light — Phototaxis 



and Photopathy ... . . . 180 



1. False and True Phototaxis . . . 181 



2. Distribution of Phototaxis and Photopathy . . 182 



a. Protista 182 



6. Cells and Cell-organs . 189 



u. Chlorophyll Bodies .... 189 

 j8. The Rearrangement of Pigment in Animal Cells 



in Response to Light 192 



y. The Migration of Pigment Cells in the Metazoan 



Body . . 193 



c. Metazoa . . 194 



3. The General Laws of Phototaxis and Photopathy 196 



a. The Sense of the Response . . . . 196 



b. The Effective Rays . 201 



c. Phototaxis vs. Photopathy . . 203 



d. The Mechanics of Response to Light 207 

 Summary of the Chapter .... . . 210 



Literature 212 



