CONTENTS xin 



PAGE 



34. General Conception of the Colloidal State. Fundamental Prop- 

 perties of Colloids. Phenomenon of Swelling 102 



35. The Cell as a Colloidal System. Osmotic Properties of Cell 

 Membranes. General Laws of Osmosis 107 



36. Impermeability of Protoplasm and the Phenomenon of Plasmolysis. 

 The Osmotic Properties of Cell Sap and Methods of Its Determina- 

 tion 112 



37. Substances Causing Temporary Plasmolysis. Permeability of the 

 Protoplasmic Membrane to Different Substances and the Problem 



of Its Composition and Structure 110 



38. Conditions of Accumulation of Soluble Substances in the Cell. 

 Importance of Chemical Alteration in Substances for Their 

 Accumulation. Donnan's Membrane Equilibrium 110 



30. Changes in the Colloidal State of Protoplasm and Its Influence 



on Osmotic Properties. Coagulation and Death of Protoplasm . . . 123 



40. Influence of Low Temperatures on Plants. Freezing and Winter 



Killing 124 



CHAPTER V 



Absorption of Water 130 



41. General Idea of the Water Balance. Amount of Water Absorbed 



by Plants 130 



42. Laws Governing the Entry of Water into the Cell. Suction 

 Tension and Methods of Its Determination 132 



43. Suction Tension and Exudation Pressure of the Root System. 

 Root Pressure, Guttation and Bleeding of Plants 136 



44. The Osmotic Mechanism of Root Pressure 130 



45. Absorption of Water from the Soil. The Water-retaining Forces of 

 the Soil. Available and Inavailable Water 143 



46. Influence of Environmental Conditions on the Absorption of 

 Water. Methods of Studying the Absorption of Water by Roots. 147 



47. Absorption of Water by Aerial Parts of Plants 150 



48. Absorption of Substances Found in Soil Solution 152 



CHAPTER VI 



The Loss of Water by the Plant 155 



49. Transpiration. Its Role in the Life of the Plant 155 



50. Methods of Studying Transpiration and Units of Measurement. . . 156 



51. The Physical Nature of Transpiration. Its Dependence on 

 Environmental Conditions and Its Daily March 161 



