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: transparency, etc., p. 26. Stratification, 

 p. 31. The content of natural waters, p. 40. 



//. Water and land, p. 55. 



CHAPTER III 

 Types of Aquatic Environment 



I. Lakes and Ponds: Lakes 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, p. 68. Depth and 

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



77. Streams: Gradient of stream beds, p. 77. Ice in streams, p. 80. Silt, 

 p. 84. Current, p. 85. High and low water, p. 87. 



///. Marshes, swamps and bogs: Cat-tail marshes, p. 91. 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: The Algae, p. 101. Chlorophylless water plants, p. 139. The 

 mossworts, p. 146. The fernworts, p. 149. The seed plants, p. 151. 



II. Animals. Protozoans, p. 159. The lower invertebrates, p. 163. Arthro- 

 pods, p. 183. Insects, p. 195. Vertebrates, p. 231. 



