XVI 



CONTENTS 



IX. The Power or Energy of the Plant 



§ 218. Energy of the plant 



§ 219. Sources of energy 



§ 220. Sunlight as a source of energy . 



§ 221. Chemical compounds as a source of energy 



§ 222. Physical attraction as a source of energy 



§ 223. Release of energy 



§ 224. Respiration, or breathing .... 



§ 225. Changes in the air produced by breathing 



§ 226. Plants by day and by night 



§ 227. Relation of the living world and the atmosphere 



§ 228. Energy of physical attraction .... 



§ 229. Outward work accomplished by physical attraction 



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182 

 182 

 183 

 183 

 184 

 184 

 184 

 185 

 186 

 187 

 189 

 190 



X. Relations of Plants to Each Other, and the 

 Place in which they Live 



§ 230. Societies and communities 191 



§ 231. Plant societies 192 



§ 232. Foundations of society 192 



§ 233. Communities change 193 



§ 234. AVater and plants 194 



§ 235. Temperature and plants 194 



§ 236. The soil and plants 195 



§ 237. Light and plants 195 



§ 238. Wind and plants 196 



§ 239. Forests . . . . . ... . . .196 



§ 240. Relations of members of the forest 201 



§ 241. Time of blooming 201 



§ 242. Seasonal activity 202 



§ 243. Families and species in a community .... 204 



§ 244. Meadows 205 



§ 245. Rock societies . .206 



§ 246. Pond societies 207 



