STUDIES IN PLANT REGENERATION 211 
placed pieces with buds cut out have behaved in all respects exactly 
like the erect pieces. 
In order to obtain information as to the behavior of the aerial 
shoots of the potato, before and after such excision of the axillary 
buds, experiments were set up in which at first only the basal bud 
and then progressively more buds were taken away until finally 
the cuts included the growing points of the stem. 
Experiment 19.—The tops of such shoots, always exclusive of 
the lowest three internodes, were planted. The leaves were re- 
moved from the portion below the sand level. The parts rooted 
quickly but sparingly from the end of the internode ; but when 
these roots were rubbed off, as frequently happened in taking up 
the cuttings for examination, no new ones formed. Notwith- 
standing this, the lowest axillary bud, which had been present at 
the beginning of the experiment as a small green rudiment in 
which the leaves were just visible, after five weeks became 
changed into a small tuber. This grew right up against the stem 
without any visible stolon. 
Experiment 20. — The buds at all the nodes under the sand 
level were next removed. Roots were produced, as before, and 
at the first node above the earth а tuber was formed on a short 
stalk. It became green through exposure to the light, and the 
small leaves could be seen on it. When the leaf remained attached, 
a sessile tuber was formed in the axil. 
Experiment 21.-- Іп this series only the buds at a few of the 
apical nodes were allowed to remain. Again at these nodes, 
stalked tubers grew which were 15 cm. above the sand. ; 
Experiment 22. — Finally all the buds, including the terminal 
buds, were excised in twenty-two pieces. Roots again formed, 
but in no case did a shoot regenerate. The pieces remained in 
the sand two and a half months but were not able to produce ` 
either a side branch or a tuber at any point. 
The results are significant from several points of view. They 
show the ease with which a tendency present in a part may be 
shifted to another when its manifestation is rendered difficult at the 
Normally it is only a few of the lower nodes from 
oreover, the experiments yield 
he light, which has been 
usual place. 
which tubers are produced. M 
additional instances of tuber-formation int 
