1897 | THE CURVATURE OF ROOTS 331 
dermis and collenchyma of the curving region of stems of 
V3cia Faba. Cieselski’s results were based upon experiments 
with Zea, Vicia, and Ervum lens, and Sachs’ results upon Pisum, 
Phaseolus, Cucurbita, Quercus, Polygonum, Lepidium, Zea, 
Triticum, Vicia, and Asculus. So far as I have examined the 
above mentioned species my conclusions as to the behavior of 
the cortical cells of the convex side agree with those obtained 
by Sachs. But in material, such as the roots of Phoenix, pre- 
senting different mechanical conditions I have found an action 
of the convex side similar to that wrongly ascribed to Zea by 
Cieselski. I am at a loss to account for his mistake in the 
matter. 7 
XI. SCOPE OF EXPERIMENTS. 
In addition to the experimental results adduced in the pre- 
ceding portions of this paper, chief attention has been paid to 
the collection of data bearing upon the mechanism of curvature, 
with reference to the character of the changes ensuing in the 
motor zone during curvature. To this end a series of experi- 
ments was devised by which reaction curvatures were obtained 
in the following manner: Geotropic curvatures were obtained 
by placing seedlings in such position that the radicle pointed 
nearly vertically upward, and the curved portions, inclusive of 
the apex, were taken, some at three, others at eight, twenty, and 
Seventy hours after the excitation began. The roots were in 
moist air, sawdust, or earth, at temperatures between 16 and 20° 
C. Mechanically curved preparations of the motor zone were 
made as follows: Two pins were driven in a plate of moist 
cork at a distance apart slightly in excess of the diameter of the 
apical portion of the root. The root was thrust between these 
Pins in such manner that when the basal portion was moved to 
one side a curvature would be produced in the motor zone. To 
a erteh the bending a third pin, placed against the side of 
ne root, was slowly moved laterally until the root was bent 
at right angles when the pin was thrust in the cork, and the 
Satire Preparation immersed in a mae solution. Some 
