CONTENTS 



CHAPTER I 

 Introduction 



The study of water life, p. 14. Epoch-making events: the invention of the 

 microscope, p. 15. The publication of the Origin of Species, p. 17. The 

 discovery of plancton, p. 18. Agencies for the promotion of the study 

 of limnology, p. 20. Biological field-stations, p. 23. 



CHAPTER II 



The Nature of Aquatic Environment 



I. Properties and uses of water: p. 25. Transparency, p. 26. Stratification, 

 p. 31. The yearly cycle, p. 35. The thermocline, p. 37. The contents 

 of natural waters, p. 40. 



//. Water and land, p. 55. 



CHAPTER III 

 Types of Aquatic Environment 



I. Lakes and ponds: p. 59. Lakes as temporary phenomena, p. 60. The 

 Great Lakes, p. 63. The Finger Lakes, p. 64. The lakes of the Yahara 

 valley, p. 66. Flood plain lakes, p. 67. Solution lakes and ponds, p. 68. 

 Depth and breadth, p. 71. High and low water, p. 74. 



//. Streams: p. 77. Gradient of stream beds, p. 77. Ice, p. 81. Silt, p. 84. 

 Current, p. 85. High and low water, p. 87. 



///. Marshes, swamps and bogs: p. 89. Cat-tail marshes, p. 91. The 

 Okefenokee Swamp, p. 93. Climbing bogs, p. 94. Muck and peat, 

 p. 95. High and low water, p. 96. 



CHAPTER IV 



Aquatic Organisms 



I. Plants: p. 99. i. Water plants, p. 100. The Algae, p. 101. Chloro- 



phylless water plants, bacteria and fungi, p. 139. 



2. The higher plants, p. 145. The mossworts, p. 146. The fernworts, 

 p. 149. Aquatic seed plants, p. 151. 



