OF TREE BRANCHES AT FREEZING TEMPERATURES 39 
ject, the problem being to find the atmospheric conditions under 
which the movements took place, and to determine the extent 
of the effect produced. To illustrate the interesting phenomenon 
under discussion, photographs (Fics. 1-3) have been taken. 
In Fic. 1, the extent of movements can be seen at a glance. 
The photograph has been artificially arranged with the addition 
of a duplicate photograph of a branch, fitted in according to scale, 
and is given here solely to show the magnitude of the effect. 
The upper branch shows the position as it was at 32° F. or above; 
and the lower one, the same branch as it was at approximately 
10° F. This very large movement shown indicates some inter- 
esting processes going on within the living portion of the branch. 
METHOD OF MEASUREMENT AND SPECIES OF TREES STUDIED 
The apparatus used consisted of a specially constructed meas- 
uring rod, a steel tape, and thermometers. The linear measure- 
ments are given in feet and hundredths of feet. The temperatures 
are given in Fahrenheit as being more convenient, although many 
sets were taken in Centigrade. The Fahrenheit scale was used 
to compare temperatures with temperatures taken from a record 
of the United States Weather Bureau, which are expressed in 
Fahrenheit. Also, the temperature curve continually crossed the 
freezing point of water; hence the use of the Fahrenheit scale 
avoided the employment of the + and — sign. The heights 
of four branches from the ground were measured, three species 
of trees being selected, and also the distance from the point 
on the branch measured, as indicated by a plumb line, to the 
trunk of the tree in a horizontal line. The latter measurements 
are not given in this paper, since they correspond in general to 
the vertical measurements. 
Two similar curved branches of a European linden tree desig- 
nated as Tree No. 1, were measured; also, a branch of a Paulownia 
tomentosa, designated as Tree No. 2, similar in shape to the 3 
branches of Tree No. 1, and a horizontal branch of an oriental 
plane-tree or sycamore (Platanus orientalis) recorded as Tree 
No. 3. 
It was to be regretted that branches of the linden of various 
shapes were not measured, but the observations that were made 
