OF TREE BRANCHES AT FREEZING TEMPERATURES 43 
to the changes in the temperature of the air. While observations 
were not taken every hour, they were frequent enough to obtain 
the results required. It is seen in Fic. 9, which gives observation 
where the temperature rises to a maximum just above the freezing 
point of water, that both branches begin to fall with the tempera- 
ture within a quarter of an hour after the high point of the tem- 
perature has been reached and before the temperature passes 
through the freezing point. This seems to show that there is a 
very small thermometric effect just above 32° F. The same 
fact is indicated in other observations. In Fic. 10, three branches 
were measured and the resulting curves show the effect on the 
Fic. 12. Photograph of Branch A, Tree No. 2 (Paulowina tomentosa). 
branch showed little or no thermometric changes. The branch was selected because 
of its similarity in shape to Branches A and B, Tree No. 1. 
branches when the temperature of the air rises to @ maximum, 
below the freezing point of water, and then falls again. C observa- 
tions in this set were taken at the extremity of the branch and 
hence show the largest movement. 
