OF TREE BRANCHES AT FREEZING TEMPERATURES 45 
temperature repeatedly passed through the freezing point of water. 
There is, however, a continual rise of the branch from ear y 'n 
February till May. This elevation is evidently a response to heat 
and light of the sun, and being a seasonal change, is an entirely 
different effect from that observed in the linden. 
Fic. 14. Photographs of Branch A, Tree No. 3, sycamore (Platanus ori- 
entalis). Measurements shown in Fic. 15. This branch differed from others 
measured in being straight and nearly horizontal. 
In Fic. 15 an intermittent record of the height of a straight 
branch of a sycamore tree, Platanus orientalis, Tree No. 3, from 
February to well along in April, is given. Here also no thermo- 
metric movement is observed, the gradual rise of the branch 
recorded being a seasonal change. These observations merely 
show that in certain trees there is no thermometric movement 
of the branches. 
THE ELASTIC CONSTANT OF BRANCHES ABOVE AND BELOW FREEZING 
In Fic. 16 s shown a plot of an experiment which consisted 
in weighting the branches of both Tree No. 1, the linden, and Tree 
