vi CONTENTS. 



PAGE 



Photosynthesis ...".. 37 



Physical properties of chlorophyll . . . " -39 

 Division of the spectrum . ... . . . 4^> 



Product of photosynthesis . 41 



IV. RESPIRATION AND OTHER FORMS OF METABOLISM. 



Nature of metabolism 43 



Respiration ............. 43 



Absorption of oxygen and excretion of carbon dioxide . . . .44 



Liberation of heat 45 



Respiration essential to growth 4^ 



Fermentation . . . . V. 47 



Changes in color . ..- , . . 49 



V. IRRITABILITY. 



Nature of irritability . ' . . . .. 50 



Perceptive zone, motor zone . . . ~. . . .50 



Geotropism . . v . . . . . . . .51 



Perceptive and motor zones of roots . , . .52 



Amount of influence of gravity . * . * . . . .54 



Replacement of gravity . . * . ... . . .55 



Heliotropism, thermotropism, etc. . . . . * * .57 



Periodic movements . . . . .61 



Hydrotropism . T . . ' * . . . . 62 



Contact movements . . . . * ." _. . . . .62 



Circumnutation ... .... .66 



Hygroscopic movements . . . -^ *. . . .66 



VI. GROWTH. 

 Nature of growth . '. , . . . .68 



Grand period of growth . . . . . -. -7 



Influence of light on growth 72 



Influence of light on anatomy of leaves . . ... . .73 



Influence of light and gravity on the formation of organs . . .74 

 Influence of temperature on growth . . . ... . .75 



Sources of heat . . . ... . . . . . .76 



Relation of temperature to distribution . . . m . . .76 

 Freezing of plants ... .* . . . . . . .77 



Relation of moisture to freezing 78 



Lpss of heat . . . . . ... . . . 7 So 



Resting period . .. . . . . ... . .So 



Correlation processes . . .... . . . . .Si 



Mechanical force exerted by growing organs Si 



APPENDIX . . . 84 



INDEX . . . 87 



