GRAVITATIONAL SENSITIVENESS OF THE ROOTTIP. 271 
from too copious water-supply it is impossible to say. But the 
great majority failed because the root slipped out of the tube: 
they cannot therefore be fairly held to invalidate the general 
principle, but rather to show the difficulties of the method. 
Figs. 7 and 8 are reproduced from drawings, kindly made for 
me by Miss D. F. M. Pertz, of the results of the experiments of 
March 30 and May 24, 1900. 
Fig. 7. Fig. 8, 
2) 
Curvature of a bean- Curvature of a bean-root produced in three days 
root produced in two (May 24, 1900). The tube in which the root 
days (March 30, 1900). is fixed was somewhat oblique. 
The following notes refer to fig. 7 :— 
March 27, 1900, 10 p.m.— Vicia Faba fitted in a horizontal straw- 
tube, a piece of wet gauze hanging over the tube and the 
apical part of root and tending to keep the root in place. 
Curvature. 
March 28, 6.30 a.m. 60° —s a. e., the root had geotroped 
through 60°. 
” 12.47 P.M. 87 i.e., nearly vertical. 
» 10 P.M. 120 (30° beyond vertical.) 
March 29, 8.35 a.m. 200 
» 10.23 a.M. 230 i. e., the base of root is 50° 
above the horizon. 
March 80, 8.20 a.m. Growth stopped, root becom- 
ing unhealthy. 
