CONTENTS. 



PART IV : ECOLOGY. 



PAGE 



Chapter XIX. Forms of vegetation 30S 



XX. Mesophytes 312 



XXI. Xerophvtes and halophytes . . . 318 

 XXII. Hydrophytes 327 



XXIII. Adaptations to other plants as supports 330 



XXIV. Symbiosis 333 



XXV. Animals as food, foes, or friends . . 342 



XXVI. Protection and distribution of spores 



and seeds 352 



Appendix I. Directions for laboratory study . . . 369 

 II. Directions for collecting and preserving 



material 401 



III. Apparatus and reagents 409 



IV. Reference books 413 



V. Outline of classification .... 415 



Index 4*9 



