174 BOTANICAL GAZETTE [FEBRUARY 
2. Those shoots which grow out first attract automatically the 
material available for shoot formation, thus withholding it from the 
other buds; the mechanism of this automatic attraction is not yet 
known. 
3. These two factors, the limited amount of material available 
for growth and the automatic attraction of the material by the buds 
which grow out first, explain the inhibiting effect of these buds on 
the growth of the other buds. 
4. The relative amount of water in a notch determines which 
notches give rise to shoots first; by supplying a liberal water supply 
from without or from within we can determine at will which notches 
shall grow out first. 
ROCKEFELLER INSTITUTE FOR MEDICAL RESEARCH 
EW York City 
