1897] THE CURVATURE OF ROOTS 349 
epidermal layers are torn and collapsed, and the cortex shows 
the ordinary foldings of the end walls much more marked than 
those of the mechanically bent organ. On the whole, the cur- 
vature of the organs geotropically excited is not distributed over 
so great a region as in those bent mechanically from a normal 
condition. This might of course be due to a smaller coefficient 
of turgidity, and the recurrence of this relation through all 
of my experiments leads to the suggestion that some alteration 
must have taken place in the membranes to permit the localiza- 
tion of the curvature. Furthermore, it is impossible to account 
for the excessive folding and wrinkling of the walls of the cells 
of the concave side, with decrease of the resistance of the mem- 
branes of the convex side, as due to stretching. This decrease 
would allow a greater part of the bending force to act as a com- 
pression upon the cortex of the concave side. 
TABLE XI. 
Median longitudinal section of normal root. The measurements included 
a region beginning at a distance of 2™™ from the tip of the growing point 
and of the same age and stage of development as the curved portion of the 
root described under table V. 
MEASUREMENTS OF LENGTH OF CELLS OF SIDE A. 
i Basal 
Apical Average 
(Ep) 7 8 7 II es 8 7 Io Io 9-37 
ee Ce eS eg a ie $2 0 16. 
). 42 II 16 10 14 15 II 21 16 15-75 
(4) 21 II 20 II 14 14 10 12 15 16. 
OS ie coe cs Fe a , foe 14.88 
yas a a6 a ae a + ee 16.75 
(7) fe) Io 16 20 16 15 15 fe) 10 15.25 
(8) ou sae to. ti yee i . 4a 14.62 
Average lengthof cells, - - - - - - 1482 
MEASUREMENTS OF LENGTH OF CELLS OF SIDE B. 
Apical Basal —S—- Average 
fe) 7 8 6 6 II 6 6 7-5 
Io 9 18 14 25 12 15 15.12 
, ee es eee ae 7. 8 ioe 
rt 4 72 10 12 10 ro FEL? 
