266 BOTANICAL GAZETTE [OCTOBER 
the same time accelerates the latter’s regeneration or makes it 
possible. | 
The second example is the following: When we cut off one leaf 
with a piece of the main stem (as in fig. 2) and suspend it in water, 
the bud opposite the intact leaf will grow out into a shoot (S in fig. 2). 
We have seen that the growth of this shoot has a share in the inhibi- 
tion of the growth of the notches of the leaf in this experiment. It 
can be shown that conversely the leaf accelerates or renders possible 
the growth of the bud in the stem. As stated, the isolated node © 
near the top will not be able to form shoots if suspended in moist air. 
If, however, one leaf or even 
a fraction of one leaf is left in 
connection with the stem, the 
a bud on the opposite side will 
' grow out (figs. 25-29). In 
24 . the isolated nodes (figs. 28, 
29) cut off near the apex no 
Fics. 23 AND 24 buds could grow in moist air. 
When, however, only a piece 
_of a leaf was left in connection with such a stem, as in fig. 25 
or 26, the bud could grow out. Here we see again that 
the presence of the leaf accelerates or renders possible the 
growth of that shoot in a stem whose formation inhibits or 
retards the growth of the notches of the leaf. 
This gives us a clue to the nature of the dominance and 
the power of inhibition. The inhibition seems to consist in 
this, that the dominant part receives something from the inhibited 
part which accelerates growth or renders it possible in the former. 
When we put an isolated node from near the top (whose 
leaves are removed and which cannot regenerate in moist air) in 
a very thin layer of water, new shoots grow out (figs. 30-32). This 
looks as if the “something” which the inhibited part supplies to 
the dominant part were water. But the writer is suspicious that 
the water may be only indirectly needed, namely to render the flow 
of material in the conducting vessels possible. In animals we know 
that the blood vessels must be filled to render a closed circulation 
possible. It would seem as if in plants a flow of substance through 
23 
