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 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 Egwisetum, grasses, rushes, &c.; mode of 
formation of the reservoirs—External orifices of. the intercellular 
space system; stomata and Jenticels—Relative dimensions of 
cellular tissue and intercellular spaces—Movements of air in inter- 
cellular space system—Composition of the air. . - 109-123 
CHAPTER vir @ | 
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 1X (%) 
. THE ABSORPTION OF FOOD MATERIALS BY A GREEN PLANT 
See 
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 . 3 3 r ‘ , . 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— 
