1905] Mc CALLUM—REGENERATION IN PLANTS 253 
directly above the other or on different sides, be cut, roots come 
from above each of them, but more vigor- 
ously from the upper ones, due probably 
to that part being nearer the source of food 
supply. Or when stems are cut through, 
some at the base and some higher up, the 
roots appear perceptibly sooner on the 
latter. No matter where. the stem is cut 
off, roots develop immediately above this 
point, showing that the pericycle has the 
power to produce roots at any point. Yet, 
as has been stated, if the stem be cut off, 
say near the base, roots come only here, 
though the whole 
stem is submerged 
in water. But when 
the cut ends of the 
stems were encased 
in plaster so as to 
prevent roots from 
coming there, they 
came further up. 
Also stems whose 
lower internodes 
were 1o-12°™ long 
were placed in 
water, andevery day 
ig OPE 0.5°™ was cut off. In 
Lower internode of stern, ten days roots ap- 
a diferent sides Peared scattered 
merged Pactely sub- along the remain- 
4 cots appear . 
only above the notches. amg part. 
ee ; Ex periment 47.— 
ica : stems with Toots intact were 
ae -. by glass cylinders 4-5°™ long 
a oa © air-tight at each end by means 
T stoppers and wax, and opening 
G. 7.—Phaseolus: Part of 
phe to dotted line 
above which stem is notched 
to center. Roots appeared in 
tube, arising only on side 
directly above notch. 
