CONTENTS. 



PAGE 



Introduction 7 



1. Respiration and oxygen 8 



Normal respiration of roots 8 



Early researches 8 



Later researches 12 



Recent researches 16 



Summary 26 



Aerotropism 28 



Summary 32 



Air of soil and plants 33 



Air-content of the soil 33 



Earlier researches 33 



Later researches 38 



Summary 42 



Air-content of water 45 



Summary 49 



Influence of algse and water plants 



on oxygen-content 50 



Summary 52 



Air-content of plants 53 



Summary 56 



Anaerobic respiration 56 



Respiration 57 



Early researches 57 



Later researches 57 



Recent researches 62 



Summary 65 



Photosynthesis 67 



Summary 68 



Transpiration 69 



Summary 71 



Germination 71 



Early researches 71 



Later researches . . 73 



PAGE 



1. Respiration and Oxygen Cont'd. 



Germination Continued. 



Recent researches 75 



Summary 78 



Growth 79 



Early researches 79 



Later lesearches 80 



Recent researches 83 



Summary 87 



Protoplasmic streaming and mitosis 88 



Summary 91 



Irritability 91 



Summary 94 



Fungi 95 



Summary 97 



Aeration as an ecological factor ... 98 



Summary 107 



2. Bog xerophytes and acid soils. Ill 



The nature of bog xerophytes Ill 



Earlier views Ill 



Later views 117 



Causes and interpretations of bog 



xerophytes 123 



Acidity 130 



Summary 140 



Conclusions 141 



3. Toxic exudates and soil toxins 144 



Early views 144 



The Woburn researches 146 



Researches of the Bureau of Soils 151 



Other researches 154 



Conclusions 158 



Bibliography 163 



5b(o 



