276 BOTANICAL GAZETTE [OCTOBER 
XI. Summary of results 
The phenomena of inhibition of regeneration have been studied 
in Bryophyllum calycinum and it was found that they are governed 
by the following simple rule: 
If an organ a inhibits the regeneration or growth in an organ 8, 
the organ b often accelerates and favors the regeneration in a. 
This rule is best understood on the assumption that the inhibit- 
ing organ receives something from the inhibited organ necessary 
for regeneration. 
It is pointed out that this harmonizes with the older assump- 
tion of botanists and of the writer that the flow of material and the 
block to such a flow after mutilation is responsible for the phe- 
nomena of inhibition in regeneration, as well as for the phenomena 
of correlation. 
ROCKEFELLER INSTITUTE FOR MEDICAL RESEARCH 
New York City 
