342 BOTANICAL GAZETTE [May 
The width of the sections from which above measure- 
ments were taken is 1. 12™™; the width of the cortex (including 
the epidermis) of the concave side is .4™™, and of a similar 
region on the convex side .3™". The mechanics of cells are to 
be compared with the data given in tables I to V, since the 
amount of curvature is not much greater. The differences are 
to be ascribed to changes brought about by growth subsequent 
to curvature. 
The epidermal and sub-epidermal cells of the concave side 
are more densely granular than those of the convex side. The 
emergences from the epidermal system are very few, and the 
walls of all of the cells show a thickening noticeably greater 
than those of the convex side. The foldings of the end walls 
seen in the sections described in the preceding tables are not to 
be found here. On the other, the end walls of the cells of the 
convex side exhibit more sharply folded bends than those 
described in tables V-VII. The epidermal cells exhibit a 
normal number of emergences, as well as the flanks of the 
organ. The epidermal and sub-epidermal walls do not show 
the evidences of the tensions to be seen in younger curvatures, 
and the suggestion arises that these tensions may have been in 
part relieved by growth subsequent to curvature. This growth 
would follow, of course, the laws governing growth under ten- 
sions, by which the first accession of strains would retard elonga- 
gation, to be followed later by an accelerated elongation, which 
would obliterate evidences of tension. 
TABLE VIII. 
Median longitudinal section of root of Zea mais geotropically excited and 
curved through go”. Portion of root containing curvature killed after tip 
reached a distance of 3" from the cross section having the shortest radius of 
curvature, 
MEASUREMENTS OF LENGTH OF CELLS OF CONVEX SIDE. © 
j . Apical Basal Average 
(Ep) ee ce 3 He sue 
GQ We 10 tem AS 
PN gee. ie i SR 
