360 BOTANICAL GAZETTE [MAY 
TABLE XV. 
MEASUREMENTS OF CELLS IN CURVED PORTIONS OF ROOTS OF ZEA. 
Convex Concave Convex Concave 
Normal roots, - . - : = (24352 ¥x.35 8.29 8.047) 
Recurved to 15°, - - - - - 56.04 57:77 7.16 7.18 
Geotropically curved 60°, - - 43-3 29.9 7.56 8.29 
Mechanically curved go”, - - - 61.4 56.85 6.98 8.04 
Geotropically excited and mech. curved, 44.63 30.32 7.gt 9-3 
Geotropically curved 105°, - - - $8.05 24.7 6.68 tis 
Geotropically curved (old) go’, - 71.99 45.00 8.53 11.69 
Geotropically curved (old) 160°, - - 78.75 25.28 10.05 12:52 
The comparison of the measurements of the cells of a region 
allowed to curve five hours, and then in the opposite direction for 
fifteen hours, with the curvatures of three and twenty hours 
duration is of interest. The length attained by the cells of the 
convex side in three hours is 43.3, and of the concave side is 
29.9. The length of the cells of the concave side atter recurva- 
ture of the portion apical to it is 57.7, and of the convex side 
36.04. If it be taken for granted that the two measurements 
are of regions strictly correspondent, it can be assumed safely 
that during the five hours in which curvature was allowed to 
proceed normally the length of the cells of the convex side 
became greater than 43.3, and of the concave side greater than 
29.9. On the reversal of the root and its excitation in the 
opposite direction, a curvature would be induced in a region 4 
distance apical to the curvature of the shortest radius, by the 
amount of growth elongation of the tip of the root during five 
hours. The region of the new curvature would not be identical 
with that of the old, but would overlap a portion of it and 
extend apically a short distance. The new changes set up would 
affect the entire region of the old curvature by the mechanical 
strains set up. The compression of the concave side would be 
released, and the stretching of the convex side would be met. 
It would appear, therefore, that the cells of the convex side had 
undergone no contraction on the release of the first excitation, 
and had grown from 43 to 56 in fifteen hours. Then the cells of 
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