One space= ro days 
1915] BROWN—PINUS STROBUS : 215 
The results given in table F are represented in graph 1. The 
abscissas indicate the daily gain and the ordinates the time inter- 
vening in 10 day periods. From the way in which the lines cross 
and recross, it is evident that average growth intensity and the 
actual amount of growth which is correlated with it vary between 
wide limits during different periods. The cambium may be very 
active for a time, then slacken in its growth, this to be followed 
again by renewed activity, with a final slump toward the end of 
i “ee 9-19+/3 
poke a 8 
N. ty oe 
ot ane SON 
12 owe ee 
r is = 
Pian me ie po i B34 /3; Be we 
a gS Feel 
oe 2 
=> 
8 ue ont pe a asst 1 
we Be 2a 4 a, 
oe \ | 7-9 7/5] r, 
e—— 
\ ee ee LT | 
2 ee tL >| 2- ++ 
ye 9 eat ~ Pe —/P—|/Z3 f= 5 
say 2 a lsat: 
4 in 4 
ae 4 
oe ae i Le ons a a = Pe 5—-V2+/ 3 
te — T | 
——<—— 
0 4 te ds 20 
Daily gain; one space=} 
Grapu 1.—Curves of’growth intensity, tree I, 1913 
the growing season. All the cuttings represent these two fluctua- 
tions except cutting III, and this departure may be accounted for 
through the inequalities of growth in closely neighboring parts. 
Two periodic optimums of growth intensity have already been 
noted by others. FrrepricH (7) made observations with the 
help of calipers, and found that in both coniferous and hardwood 
trees there were two periods of growth, one lasting until the end 
of May, then sinking some until the middle of June, followed later 
