1897 | THE CURVATURE OF ROOTS 355 
the concave side may not be held to have special significance, 
since similar inequalities are to be found between the sides of 
normal roots. The width of the cells of both sides is below the 
normal, and by no means sustains the proportions to the length 
to be found in other curvatures. This can be due only to the 
fact that both sides in succession have been subjected to a 
ductile stretching, and that the extension of the cells may not 
be taken up, but is irreversible after the lapse of five hours. The 
processes of growth then follow the extension of the membranes 
within this period. The foldings of the walls in the above sec- 
tions are not especially marked. 
\ 
‘ . TABLE XEIL. 
Median longitudinal section of root of Phoenix dactylifera geotropically 
excited twenty hours and curved through go”. 
MEASUREMENTS OF WIDTH OF CELLS OF CONVEX SIDE. 
Apical Basal Average 
(Ep) 8 9 8 7 7 7 z 7 7.5 
(2 Io 9 8 6 7 8 8 
(3) 5 5 5 7 5 6 5 5 5-4 
Average width of cells, . - e % 6.9 
MEASUREMENTS OF WIDTH OF CELLS OF CONCAVE SIDE. 
Apical Basal Average 
(Ep) 10 ~ 10 are. 8 8 ee 8.4 
(2) 9 Io 8 ee fe) 8 9 Ke 9. 
(3) 7 7 va 6 5 5 6 ae 6.1 
Average width of cells, = - - : - 7:8 
MEASUREMENTS OF LENGTH OF CELLS OF CONVEX SIDE. 
Apical Basal Average 
ee ee ee ee, 
er ite a a ae a es te 3 
(3) oe. ie ge ee ee 
= 7 Average width of cells, -  - - - 12d 
_ MEASUREMENTS OF LENGTH OF CELLS OF CONCAVE SIDE. 
Cee eee : 3 ea: 
Pe 3 2 2 2 3 a 2.3 
ge ee 
a (3) ees 7 5 4 ents o 5-5 
7 Se  .% 
Average length of cells, + - oe se 
