CONTENTS xiii 



PAGE 



moisture of air, rest The Potometer Suction of transpiration 

 Osmotic action of the parenchyma of the leaves and its effect 

 Regulation of all these forces by the protoplasm . . 83-108 



CHAPTER VII 



THE AERATION OP PLANTS 



Necessity of admitting oxygen to the protoplasts The intercellular 

 space system ; its origin and development ; condition in terrestrial 

 plants ; relative extent in roots, stems, leaves Air reservoirs in 

 aquatic plants ; in Equisetum, grasses, rushes, &c. ; mode of 

 formation of the reservoirs External orifices of the intercellular 

 space system ; stomata and lenticels Relative dimensions of 

 cellular tissue and intercellular spaces Movements of air in inter- 

 cellular space system Composition of the air . .,-... 109-123 



CHAPTER VIII 



THE FOOD OF PLANTS. INTRODUCTORY 



True nature of the food of plants Materials absorbed by plants, and 

 their relationship to actual food- Differences between food and 

 food materials Construction of food from the latter Assimilation 

 of food Intricacy of the metabolic processes of plants . , 124-131 



CHAPTER IX 



THE ABSORPTION OF FOOD MATERIALS BY A GREEN PLANT 



Examination of substances absorbed from the soil ; water-culture ; 

 destructive analysis Classification of materials absorbed The 

 ash of plants Conditions of absorption of substances in the soil 

 Absorption of nitrogen by leguminous plants Absorption of 

 metallic compounds ; silicon Absorption of carbon dioxide from 

 the air ; its mechanism 132-145 



CHAPTER X 



THE CHLOROPHYLL APPARATUS 



Formation of organic substances from the inorganic materials 

 absorbed Chlorophyll Structure of a chloroplast Properties of 

 chlorophyll ; its absorption spectrum Xanthophyll Erythrophyll 

 Composition of chlorophyll Distribution of the chloroplasts . 



