1902] THE RHEOTROPISM OF ROOTS 281 
j 5 a 1 a = mi 
ee enabled toattain toa i y greater 
heliotropic angle. The continuance of this behavior brings about 
_ aconstant straightening of the geotropic curve in its proximal part 
_ andaconstant re-formation of the geotropic curve in its distal 
part, giving in a root of Raphanus sativus that has been in its 
_ theotropic and geotropic equilibrium for some 
hours, 2" to 3™ of the apex dipping to an 
angle of 45° to 15° from the vertical, back of 
: this apex a straight piece from several to 
many millimeters in pength, generally lying at 
an angle of 45° to 90° above the vertically 
downward position, and lastly the rheotropic 
angle i in the form of a more or less open arc 
connecting the rheotropically growing piece  geotropic —counter- 
of the Toot with the older vertical part. “'" 
11, drawn from a root of Lupinus albus, illustrates the fea- 
just described. 
The rheotropic curve at the beginning may be quite like be 
4€ curve of a root, but after some hours it will be noted 
4 5 6 7 8 o 10 
bers 7 to g are tracings of the rheotropic curves of a single seedling . 
> during the period of five hours. Numbers 5 to 8 nh tracings of 
€ at the same time. Numbers g and zo show the g 
nus sativus, The difference in the character of the reotropic 
is apparent to the eye. 
: 12, nos. r to 8, shows rheotropic eT : 
t sadiens, all made at the same time gone 
“The 
