CONTENTS XI 



PAGE 



stimulus — Phenomenon of alternating response — Dual effects 

 of stimulus of light — Unmasking of the A effect — Effect of 

 chemical agents — Effect of tonic condition on response . . 49 



CHAPTER VIII 



CHANGE IN PHOTOSYNTHETIC ACTIVITY UNDER 

 STIMULUS, ANESTHETICS AND POISONS 



Effect of stimulus, minimal and maximal, on photosynthesis — 



Effect of chloroform, ether and alcohol — Effect of poison . . 60 



CHAPTER IX 



EFFECT OF INFINITESIMAL TRACES OF CHEMICAL 

 SUBSTANCES ON PHOTOSYNTHESIS 



Sudden increase of photosynthetic activity after a thunder-storm — 

 This possibly due to nitrous fumes produced during electric 

 discharge being washed down by the rain — Determination of 

 the effect of infinitesimal traces of HN0 3 in enhancement of 

 photosynthetic activity — Effect of traces of extract of thyroid 

 gland, of iodine, and of formaldehyde — Opposite effects of large 

 and small doses on physiological reactions .... 66 



CHAPTER X 



THE ELECTRIC RESPONSE TO LIGHT 



Electric response to the stimulus of light — Dual reactions A and D 

 under light — Excitatory D reaction detected by response of 

 galvanometric negativity — Persistence of electric response of 

 motile organs even under physical restraint — The photo-electric 

 cell — The predominant D effect in the electric response of Mitsa 

 to light — The positive after-effect and the phenomenon of ' over- 

 shooting ' — Positive electric response of Hydrilla — Effect of 

 temperature on electric response — Effect of narcotics — Effect of 

 excess of carbonic acid ....•••• 73 



CHAPTER XI 



PHENOMENON OF PHOTOSYNTHETIC INDUCTION 



The relation between the quantity of light and the amount of photo- 

 synthesis under continuous light — ' Uphill ' or positive work — 



