xii LIST OF ILLUSTRATIONS 



19. Nardua stricta and Sagina procumbens ; 



examples of hereditary depauperism . To face page 82 



20. Asparagus, Tamus and Avena, showing two 



cotyledons .... 90 



21. R. heterophyllus, germinating seeds with 



arrested axial root .... ,. 92 



22. Mustard, germinating in water with arrested 



axial roots ,, 1)4 



23. Sidens cernua. Anatomy of roots of a laud (a) 



and aquatic form (6) . .... 98 



24. Young plants of Victoria regia and Sagittaria 



sagittifolia, showing analogous forms . . 100 



