PHOTOSYNTHESIS 



CHAPTER I 



INTRODUCTION 



Method of chemical analysis in photosynthetic investigation — Difficulties 

 of the problem, arising from complicating factors — The method of 

 evolution of oxygen by water-plants — Errors of the Bubble-counting 

 Method — New method for securing high accuracy in quantitative 

 determinations- — -Different lines of investigation on photosynthesis by 

 the new method. 



All vital activity, whether of animal or of plant, is ulti- 

 mately traceable to the energy of solar radiation. The 

 animal derives its energy from vegetable food. The plant, 

 by virtue of its chlorophyll, absorbs both solar energy and 

 carbon dioxide and builds up organic matter charged with 

 latent energy. This is, in fact, the prime source of all 

 organic matter, as well as of the energy that is set free on its 

 combustion. To stand before a coal-fire is to bask in the 

 sunshine of the Carboniferous Period. 



It is to this constructive or synthetic activity of the plant 

 that the term Photosynthesis has been applied. Like other 

 physiological processes, it cannot be fully understood until 

 it has been carefully analysed. The investigations described 

 in the present work are a contribution to the attainment of 

 this end. 



In photosynthesis a given quantity of carbon dioxide 

 is absorbed, a corresponding quantity of oxygen evolved, 

 and the end-product is a certain amount of carbohydrate. 

 Thus there are theoretically three possible means for the 

 estimation of photosynthetic activity — namely the measure- 



