42 LEAVES 
the position of the leaflets at each observation and de- 
scribe. What causes the leaflets to change their position ? 
Is this of any importance to plants? Note the difference 
in the position of leaflets in strong sunlight and that of 
those in the shade. Cover a clover plant early in the day 
so that it will be in total darkness. Study the leaflets an 
hour later. Results; conclusions? 
Exp. 26: Pick a young Nasturtium leaf with a long 
petiole, insert the petiole thru a hole in a cork into water 
in a bottle, and set the bottle onto a large sheet of white 
paper in the dark room, in such a position that the blade 
will receive light from only one direction. On the fol- 
lowing day note the change in position of the leaf, turn 
the bottle thru an angle of go degrees, rest your head 
against some fixed object about 50 cm. above the leaf, 
close one eye, and trace the outline of the leaf and the 
petiole on the paper. An hour later and again 24 hours 
later make similar tracings with the eye in the same posi- 
tion in which it was in making the first. Results; con- 
clusions? 
Exp. 27: Select a sunflower plant growing in the 
open, where the sun will shine all day. At 70r 8A. M. 
on a clear day make a diagram showing the position of 
the stem and two opposite leaves near the top as seen 
from the north. At 12 M., viewed from the same place, 
make another diagram over the first so that it will show 
the change in position of the leaves and stem. About 6 
P. M. make another diagram, over the first two, again 
showing the change in position of leaves and stem. Con- 
clusion? 
Exp. 28: Slightly touch a leaf of a sensitive plant. 
