XIV CONTENTS 



PAGE 



Correlation of the number of chloroplasts and photosynthetic 

 activity — Effect of excess of starch-content in the cell — After- 

 effect of stimulus in modifying the tonic condition exhibited (a) 

 by mechanical response, (b) by autonomous response and (c) by 

 photosynthetic response — Determination of the physiological 

 Hysteresis by the Method of Cyclic Curve — -Negative, Positive 

 and Zero Hysteresis . . . . . . . .144 



CHAPTER XIX 



THE DAILY VARIATION IN PHOTOSYNTHETIC ACTIVITY 



Effect of environmental changes on rate of photosynthesis — 

 Variation of light and temperature — Extreme sensitiveness 

 of the plant to external change — Method of simultaneous 

 determination of photosynthetic activity, intensity of light 

 and temperature — Complete apparatus for the three deter- 

 minations — The automatic records of activity throughout the 

 day — The effect of variation of intensity of light — Effect of 

 variation of temperature — The combined effect of light and 

 temperature — Resultant curve of variation . . . 155 



CHAPTER XX 



DETERMINATION OF THE PHOTOSYNTHETIC EFFICIENCY 

 OF LIGHT OF DIFFERENT COLOURS 



Contradictory views regarding the rays effective in photosynthesis — 

 Investigation by the Method of Flotation and the Torsion Balance 

 — New method of recording photosynthetic activity under 

 light of different colours — Characteristic differences in response 

 under different colours — Effect of intensity of radiation . .165 



CHAPTER XXI 



DETERMINATION OF THE ENERGY OF THE DIFFERENT 

 RAYS IN THE SOLAR SPECTRUM 



Securing pure solar spectrum — Sliding of the spectrum on to the 

 plant by a reflecting mirror — The Magnetic Radiometer — Distri- 

 bution of energy in the spectrum . . . • . .176 



