CONTENTS 



XI 



176. The measurement of responses to light 

 Adaptation 



177. Influence of chloroplasts upon form and structure 

 Form of leaves and stems . . . 

 Modification of the epidermis .... 

 The differentiation of the chlorenchym ' . 

 Types of leaves ........ 



178. 

 179. 

 180. 



ii. 



182. Heliophytes and sciophytes 



EXPERIMENTAL EVOLUTION 



183. Scope 



184. Fundamental lines of inquiry 



185. Ancestral form and structure 



186. Variation and mutation 



187. Methods 

 Method of Natural Experiment 



188. Selection of species . 



189. Determination of factors 



190. Method of record 

 Metiiod of Habitat Cultures 



191. Scope and advantages 



192. Methods 



193. Transfer 



194. Modification of the habitat 

 Method of Control Cultures 



195. Scope and procedure . 



196. Water-content series . 



197. Light series 



Chapter IV. The Formation 



METHODS of INVESTIGATION AND RECORDi 



198. The need of exact methods 161 



Quadrats 



199. Uses 161 



200. Possible objections . . . . ' . . . . 163 

 Kinds of Quadrats and Their Use 



201. Size and kinds 164 



202. Tapes and stakes 164 



203. Locating quadrats 165 



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