38 TROWBRIDGE: THE THERMOMETRIC MOVEMENTS 
movements here described may be similar to those made on small 
shrubs by Ganong. 
OBSERVATIONS BY THE WRITER IN I9I2 AND I913 
The measurements conducted during the early part of 1912, 
described below, were not made under the most favorable circum- 
stances, because it was near the end of the winter when the 
striking effects were noted and the measurements begun; also, 
there were few unusually cold periods during the winter of 1912-13. 
Enough observations, however, were taken to exhibit some intet- 
esting facts. Most of the observations in February, March, 
April and May, were made with Mr. E. Sweitzer, a special student 
in Columbia ae aes eee: during the winters ol 
0 Freezing point of water 
| 4 a ae . . es 
1 o) ty ad 
| E “Az| t | 4 
ME * of - aw,may 4 
cs a ~ 
pod Be" ‘ang Branch A 
| Sf —_—} + 4 -——1 
+ Tree No. 1 
i z a Linden fea 
3 VA 
: / 
GO} s f 
E : a 
9g 
we 
= 
PCa es my 
“ A 
J|- 
a Ss 2 
kg, peer Fr 
50,1 ‘ gg ny 
Pee BI ie a Oe ee Oe a ee 65 60 65 7 
Fic. 8. Curve showing the relation of temperature change to height of branch 
in the case of Branch A, Tree No. 1 ee Haden). The curve anos a ‘oo 
of inflection at the freezing point of water. 
due to temperature lag or to strain in the task as deteceninies by hourly eon : 
of the thermometric movements. : 
1913-14 and 1914-15 were more extended and were made by the 
writer alone. 
A study of movements of the branches of trees under freezing 
temperature was taken up solely on the physical side of the sub- 
