44 TROWBRIDGE: THE THERMOMETRIC MOVEMENTS : 
In Fic. 11 the readings of three branches were taken under — 
conditions where the temperature had fallen to about 20° F. and ~ 
then rose. Here it is clearly shown that there is a lag amounting — : 
in time to about two hours before the branches begin to move — 
upward, although a change in the rate of the depression is observed — 
to take place as soon as the temperature of the air begins to rise. 4 
The effect on the branch of a change of temperature is therefore 1 
almost immediate with a lag depending on various conditions. — 
It is probable that the size of the branch is the ruling factor, — 
the very small branches responding almost at once to change in 
temperature. 
EXPLANATION OF CURVES SHOWN IN Fics. 13 AND 15 ; 
In Fic. 13 the daily record from February to May of a Paw 
lownia (P. tomentosa), Tree No. 2, is shown. The branch — : 
measured has the same shape as that of the linden branch shown 4 
a Daily R j HEIGHT OF BRANCH ; 
= +.[ Branch A 
ue I. 
3 ie 
wT r 5 Tree No. 2 : 
2 é 
; & Paulownia 4 
ry T T wi 
20 (eee 
5 f ig 
7 Re: 
60" é 
55 é a 
sol “A jf ae 
wa ZT NTR Li fF 
a + h 
aie \|_ T/ eNTTE Le : 
< \le \ < Frostina of water | 
30la ‘ 11 A hoa." oe 
a Soe ; q 
Prat \L ( ‘ 
ook” 4 y 
4 : 
ps 
wv * i 
1O-A+4 
gil z = 
elt FEBRUARY ; ee M .." 
1_10 13 W 15 16 17 19 20 20 29 26 96 2) 28 PI” a is 18 al 22 30 12 18 
Fic. 13. Daily record of Branch A, Tree No. 2 (Paulownia tomentosa). Record — 
for February, March, April and May. No appreciable change is shown which acy 
companies below freezing temperatures,—but a gradual rise from February to May a 
is evident and a particular response to warm days during that period is apparent. 
in Fic. 1. Here it is seen that there is little or no thermometri¢ 
effect due to the changes of temperature of the air, although t 
