CONTENTS xi 



PAGK 



moisture of air, rest The Potometer Suction of transpiration 

 Osmotic action of the parenchyma of the leaves and its effect 

 Eegulation of all these forces by the protoplasm . . . 78-102 



CHAPTEE VII 



THE AEEATION OF 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 ... 103-117 



CHAPTEE VIII 



RESPIRATION 



Dependence of the plant upon oxygen ; absorption of oxygen and 

 exhalation of carbon dioxide ; apparatus to demonstrate these 

 processes Loss of weight during respiration Variations in the 

 respiratory activity Relation between the absorption of oxygen 

 and the exhalation of carbon dioxide ; the respiratory quotient 

 Exhalation of water during respiration Respiration a function of 

 protoplasm Conditions affecting respiration ; temperature, light, 

 differences of gaseous pressure and of nutritive materials . 118-131 



CHAPTEE IX 



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 . . 132-139 



CHAPTEE X 



ABSORPTION OF FOOD MATERIALS BY A GREEN PLANT 



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

 destructive analysis Classification of materials absorbed The 



