CONTENTS 



§ 54. Method of growth of roots .49 



§ 55. Absorbing and fixing organs of the lower plants . . 50 

 § 56. Absorbing and fixing organs of the ferns, mosses, and 



liverworts 50 



§ 57. Method of fixation of the moulds and mushrooms . . 51 



v. The Leaves 



§ 58. Absorption and fixation by the algae and bacteria . . 52 



§ 59. Structure of leaves 54 



§ 60. Leaves with both surfaces alike 56 



§ 6L Compound leaves 56 



§ 62. Composition of the air 57 



§ 63. Gases of use to the plant 57 



§ 64. Functions of the leaf 58 



§ 65. The colors of leaves 58 



§ 60. Hidden chlorophyl 59 



§ 67. Characteristics of chlorophyl 60 



§ 68. Spectrum of chlorophyl 60 



§ 69. The leaf is a machine or mill 61 



§ 70. Quality of light most useful to the plant .... 61 



§ 71. Light destroys chlorophyl 62 



§ 72. Light is necessary for the formation of chlorophyl in most 



instances 62 



§ 73. Capacity of leaves for the absorption of light ... 63 



§ 74. Formation of food in chlorophyl-bearing organs . . 64 



§ 75. iSTon-green colors 65 



§ 76. Origin of red colors 65 • 



§77. Changes in color 66" 



§ 78. Autumnal colors 67' 



§ 79. Uses of autumnal colors 68 



§ 80. Uses of red and other colors in flowers and fruits . . 68 



§ 81. Characteristics of red and blue colors .... 69 



§ 82. Red color as a shield 69 



§ 83. Red color as a heat producer . . ' . . . .69 



§ 84. Red color as a heat saver 70 



§ 85. Hairs as a protection to a leaf 71 



