LIST OF ILLUSTRATIONS XIX 



Figure Facing Page 



50. A wood beam-plow .... 93 



51. A slip-nose share and a slip-nose . 96 



52. A straight knife coulter 96 



53. An iron beam-plow with rolling coulter and double 

 clevis ; .... 96 



54. A rolling cutter-harrow 97 



55. Spring-toothed harrows 97 



56. Spike-toothed harrows 104 



57. A coulter-toothed harrow 104 



58. A plank harrow I0 5 



59. To show transpiration T 8 



60. Amount of transpiration 109 



61. To show that growing leaves contain starch . .114 



62. To show that starch disappears from the leaf when 



the plant is placed in the dark 114 



63. To show that sunlight is necessary for starch-mak- 



ing by leaves . ... l l 5 



64. To show that chlorophyl is necessary for starch 



formation in the leaf IT 5 



65. To show the giving off of gas by leaves, and that 

 sunlight is necessary for it n ^ 



66. Seedling radishes reaching for light . . . .119 



67. Elm leaves injured by the "imported elm-tree leaf- 

 beetle," a chewing insect IT 9 



68. A horse-chestnut stem, showing leaves, buds, and 



scars, where last year's leaves dropped off . .128 



69. An underground stem. Buds show distinctly . . 129 



70. Flower of cherry T 3 



71. Flower of apple r 3 



72. Pistil and stamen of flowering raspberry . . .131 



73. Fower of buttercup 



74. A magnolia flower showing central column of pis- 

 tils and stamens : 34 



75. Flowers of squash J 35 



76. Flower of a lily ' I36 



77. Bud and flower of jewel-weed or "touch-me-not " . 137 



