204 BOTANICAL GAZETTE . [OCTOBER 
with the normal plant. It is impossible to state at present whether 
the substances, whose flowing away from the notches prevents 
these from growing out, are the water or solutes (sugar, amino 
acids, salts, or specific sub- 
stances). As soon as the leaf is 
cut off from the plant the flow of 
these substances away from the 
leaf ceases and the notches can 
grow out. This flow, the writer 
5 Fics. 2-5 
assumes, is caused by a “suction” on the part of the growing tips 
of the stem or the roots, the “suction” being only a symbol to 
indicate the direction of the flow. 
The experiment illustrated in figs. 1 and 2 never fails. Two 
leaves from the same node are cut off from the plant and put into 
