ie? ee ae ae 
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1900 | MECHANISM OF ROOT CURVATURE 39 
comparatively few of these roots did one side of the cortex pull 
away from the axis more than the other. Eighty-two and nine 
tenths per cent. of them kept the same relative positions with 
respect to the axis. In many cases the two parts of the cortex 
lay up close to the axis, both remaining straight. In others the 
two parts pull away from the axis at the tip, though they seldom 
curved away from it very much. The axis always remains 
straight. From this table it is seen that there is no tendency in 
the cortex of straight unstimulated roots to curve as the cortex 
of stimulated roots curves. We are justified, therefore, in the 
conclusion that stimulation is the cause of the curving effects in 
the latter, when the cortex is freed from the axial cylinder. 
TABLE XII. 
MEDIAN SLICE OF STRAIGHT ROOTS SPLIT INTO THREE STRIPS. 
In Water z In 10% KNO, 
: j Both sides One side 
Tiss = One side Both s — All ee lie cad wae stands oat, 
189 oots used eo bas vie re bditens hah A berg nai sts equally from |other lies close 
than other om axis toge pad : to axis 
Jan. 14 5 I 4 3 2 
15 4 I 2 Ai fs ms Sk 
19 6 4 2 2 I 3 
20 I I i 
Mch. 20 10 10 
30 10 10 
35 6 29 8 4 3 
17.1% 82.9% _ 53.3% 26.7% 20% 
The second part of table XII shows the effect of ssasmalyais 
on some of the roots used. The first two columns of that part 
show that, in 80 per cent. of the roots tested for this particular 
effect, there was no difference in the tendency of the cortex on 
opposite sides of the same root to curve away from the axis 
when completely plasmolyzed. 
In these experiments was first observed a very interesting 
phenomenon.. When a root with the three strips free to move 
independently is put into 10 per cent. of KNO,, the two strips 
