CONTENTS eal 
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 ‘ . 78-102 
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 Hgwisetwm, 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 
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 . . 118-125 
CHAPTER IX 
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—Insectivorous plants 
and their behaviour—Absorption of metallic compounds ; silicon— 
Absorption of carbon dioxide from the air; its mechanism . 126-140 
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—Re- 
lationship between the plastidand the colouring matter—Leucoplasts 
