LEAF ADJUSTMENT 



53 



direct. Seeds germinate, bulbs and rootstocks perform 

 their vegetative functions, and many parasites and sapro- 

 phytes grow and flourish in the dark, but in these cases it 

 is always at the expense of reserve material provided by 

 the plant itself, or by the host, through the agency of 

 chlorophyll acting in the light. 1 It is the green leaves of 

 summer that lay up the stores of food in bulbs and root- 

 stocks for winter, and 

 flowering stems will even 

 grow and blossom in the 

 dark if enough green 

 leaves are left exposed 

 to manufacture nourish- 

 ment for them. 



Pass the end of a 

 budding flower stem of 

 any green-leaved plant 

 gourd, squash, water 

 melon, morning-glory, 

 etc., make good examples 

 through a small hole 



into a dark box, leaving 105. A gourd plant developed partly in the 



the rest of the plant ex- dark and partly in the light " 



posed to light, and taking care not to bruise or injure it in 

 any way. Cover the entire leafy portion of another plant 

 of the same kind with a box, leaving only the flower bud 

 exposed, and covering, or cutting away any new leaves 

 that may appear. Watch what happens, and at the end 

 of two or three weeks compare results. The green plant 

 may not show any change for several weeks, until it 

 has used up the chlorophyll already stored away in its 

 leaves. 



Experiments like the foregoing show that it is no mere 

 figure of rhetoric to speak of the coal hidden away in the 

 earth as " stored up sunshine." 



1 Recent discoveries have given reason to believe that a few of the bacteria 

 are exceptions to this statement, but with regard to the generality of plants, it 

 holds true. 



