\ 
270 BOTANICAL GAZETTE [OCTOBER 
it is put into a Petri dish which has a very thin layer of water), each 
notch can grow out, since the inhibitants through the establish- 
ment of currents in the leaf to growing shoots are lacking. 
We have stated that if a leaf is suspended in moist air the 
growth of the shoots is prevented if a piece of a stem is left attached 
to the leaf. It seemed of interest to find out if this inhibiting effect 
would show itself even in a leaf in which a number of lateral incisions 
were made. ‘This is indeed the case, as figs. 38 and 39 show. In 
these experiments the incisions were such that the pieces of the leaf 
had to be kept together by stitches of a thread. The leaves were 
suspended in moist air. Yet complete inhibition of the growth of 
WY 
35 36 
Fics. 35 AND 36 
the notches occurred in the leaf which was connected with a piece of 
stem (fig. 38). If a flow of substances from the leaf to the piece 
of stem is the cause of inhibition, such a flow must have taken place 
along a zigzag path in the leaf. One finds occasionally in such an 
experiment that in the extreme apical piece of the leaf the in- 
hibiting effect of the stem may cease and that there a growth of 
roots may occur in the notches. 
That the flow of water and of the material it carries in a stem 
may be deviated and altered by the growth of new shoots is rendered 
obvious by such observations as are represented in figs. 40 and 41. 
In this and similar cases thick pieces of the stem of Bryophyllum 
