CONTENTS XI 



PAGE 



179. Lanate Leaves 159 



Ex-periment ^8. Study of Normal Leaf Xerophytes 159 



ISO. Other Leaf Xerophytes 159 



Experiment Jfi. Study of Xerophytic Leaves 162 



181. Stem Xerophytes 162 



182. Types of Stem Xerophytes 162 



Experiment 50. Form and Structure of Stem Xerophytes 164 



183. Mesophytes 164 



Experiment 51. Comparison of Mesophyte and Xerophyte. . . . 165 



184. Hydrophytes ' 165 



185. Amphibious Plants 166 



Experiment 52. Structure of Amphibious Plants 167 



186. Floating Plants 167 



Experiment 53. Structure of Floating Plants 168 



187. Submerged Plants 168 



Experiment 5Jf. Structure of Submerged Plants 168 



188. Bog Plants 168 



Experiment 55. Study of Water Content Types 170 



CHAPTER VIII 

 ADAPTATION TO LIGHT 



189. The Relation of Organs to Light 171 



190. Influence of the Chloroplasts 171 



191. Modifications of the Chlorenchym 172 



192. Sponge Tissue 174 



193. Palisade Tissue 1 76 



194. Changes of the Epidermis 177 



195. The Form of Leaves 178 



196. Changes of Outline, Size and Thickness 178 



197. The Form of Stems 179 



Experiment 56. The Production of Adaptations to Light 181 



198. Types of Leaves as Determined by Light 182 



199. Sun Plants and Shade Plants 183 



Experiment 57. Sun and Shade Forms in Nature 184 



CHAPTER IX 

 THE ORIGIN OF NEW FORMS 



200. The Law of Evolution 185 



201. Stability and Plasticity 1N5 



202. Constant and Inconstant Forms KS6 



203. Origin by Descent before Darwin 187 



204. Darwin and the Origin of Species ISS 



205. Evolution after Darwin 1S9 



