CONTENTS IX 



CHAPTER VIII 



THE PERMEABILITY OF ORGANIC MEMBRANES OTHER 

 THAN PROTOPLASM 



rAcm 



Permeability of some animal membranes Permeability of seed 

 coats Imbibitional forces in dry seeds Summary of results- 

 Localization of the semi-permeable layer in seed coats - 137 147 



CHAPTER IX 



THE MAGNITUDES OF OSMOTIC PRESSURES AND 



ELECTRICAL CONDUCTIVITIES IN PLANTS, AND THE 



FACTORS WHICH INFLUENCE THEM 



Introduction Leaves and other aerial organs Pressures due to 

 electrolytes and to non-electrolytes Fruits Changes during the 

 ripening of fruits Subterranean organs Seasonal variations in 

 the osmotic pressure and electrical conductivity of plant organs 

 Summary - - - - 148170 



CHAPTER X 



OSMOTIC PRESSURE IN RELATION TO PLANT 

 DISTRIBUTION, MORPHOLOGY, AND CELL DIVISION 



SECTION I. Distribution : Xerophytes Function of essential oils = 

 Salt-marsh, sand-dune, and estuarine plants Algae Epiphytes 

 and parasites. SECTION II. Osmotic pressure and morphological 

 variations ; Normal and abnormal fruits Polymorphism of 

 algae Polymorphism of fungi and structural changes in angio- 

 sperms Effect of increase and decrease of osmotic pressure upon 

 growth and irritability 171 185 



CHAPTER XI 



THE FUNCTIONS OF THE WOOD 



Researches on wood sap Concentration of total sap solutes- 

 Concentration of non -electrolytes Concentration of electrolytes 

 Variation in concentration at different levels in the conducting 

 tracts Distribution of carbohydrate reserves in the wood 

 Function of the living elements of the wood The mechanism of 

 the secretion of the wood-parenchyma cells The sugars of the 

 transpiration stream The living and non-living elements of the 

 wood A quantitative study of the areas occupied by the ele- 

 ments of the wood Functional differentiation of types of medul- 

 lary ray cells Summary 186215 



