114 THE WORK OF PLANTS 
afternoon, we will take this same leaf, remove the corks, 
and immerse it overnight in the strong chloral-hydrate 
solution to remove the green colour. Now we will rinse 
it and place it in the tincture of iodine. The part of 
the leaf which was 
covered by the corks 
does not show the 
starch reaction, while 
the other parts of the 

be that the starch dis- 
Fic. 150, Marrow leaves; at left portion of appeared from the leaf 
a oo a Re ae eee at night, that new 
ae starch was made in 
the parts exposed to the light, and that no starch was 
formed in the part covered from the hight. 
When the starch disappears from the leaf where does 
it go? Is it found in other parts of the plant not 
exposed to the light? How does it get there, and 
Where does it come from? For what purpose is the 
starch stored up in reservoirs? 
leaf do. So it must. 

