No. 458.] GEOTROPIC RESPONSE IN STEMS. 81 

The accompanying figure shows the frame turned on its side 
to bring the set of young Chrysanthemum plants into the 
upright position for observation at the close of one experiment. 
Plants 1, 3, and 4, numbering from the front, show typical 
curves. Other plants of the set gave equally good curves 
which do not show distinctly in this view. 
During alternation experiments, the frame stands on the base 

Fic. r.— Plants in turning-frame. a, base; 4, hinge-line; c, stop. 
a and the shelf hinged at 5 hangs vertically while exposing the 
stems at 9o degrees from the normal position, then is turned 
Over to stop c to make the exposure at 135 degrees from the 
vertical. 
After experimenting in this way for some time, it was thought 
that an error might have entered through closing the experi- 
ments immediately after exposing the plants in the last posi- 
tion, thus allowing no time for the appearance of its resulting 
curvature, and, in effect, giving less exposure in one of the 
two positions than in the other. To remedy this, in the later 
