xii Contents 



PAGES 



synthesis The course of photosynthesis The demonstra- 

 tion of photosynthesis The formation of sugar and starch 

 The diffusion process The amount of carbon dioxid 

 Light the source of energy Efficiency of the food-making 

 apparatus Light, intensity and quality Temperature 

 Organic matter, rate of production Laboratory work 

 References . 195-225 



CHAPTER X 

 THE RELATION TO NITROGEN 



Combined nitrogen The nitrogen content of plants Synthesis 

 of nitrogenous bodies Soil nitrogen Nitrites Nitrates 



Compounds of ammonium The sources of soil nitrates 

 and ammonia Ammonification Nitrification Nitrifying 

 organisms Conditions favoring nitrification Denitrifica- 

 tion Nitrogen fixation Organisms which fix free nitro- 

 gen Bacteria of leguminous tubercles Certain saprophytic 

 soil bacteria Fungi Mycorhizal fungi General sources 

 of supply of nitrogen Electric fixation of nitrogen 

 Laboratory work References ..... 226-249 



CHAPTER XI 

 PRODUCTS OF METABOLISM ; DIGESTION AND TRANSLOCATION 



Metabolism Temporary foods, storage products, and perma- 

 nent structures Annuals, biennials, and perennials Car- 

 bohydrates Sugars Starches Cellulose Fats and oils 



Proteins Classes of proteins Amides Organic acids 



Tannins Resins and turpentine Digestion Diges- 

 tion in different organisms Enzymes and enzyme action 

 Carbohydrate enzymes and their products Protein enzymes 



Conduction of digested foods Ringing Laboratory 

 work References. 250-279 



