216 BOTANICAL GAZETTE [MARCH 
by another maximum again in July, and then rapidly diminishing 
and ceasing altogether. Josr (13) has carried on observations 
which substantiate those of FrrepricH. It is remarkable how well 
the deductions of these two investigations are brought out in 
graph 1. 
The first optimum is without doubt made at the expense of the 
reserve food supply. It is not until June and even later that the 
bulk of the seasonal results of metabolism in the leaves is avail- 
able. This causes the second optimum, which may occur in July 
or August. It might be said in this connection that the amount 
of moisture and the prevailing temperature has been responsible 
for the results in table G. The meteorological data which follow | 
TABLE G 
METEOROLOGICAL DATA, SEASON 1913 
Mean tem- | Preci - | Precip. in 
irs eee 
PI Gk 48.1 1.49 ye as 70.4 1.59 
MAN oe Pua ee 55-4 3.15 A (Soares ne arse 69.6 1.92 
Hime 65.0 2.00 || September....... 61.0 3-28 
are the best refutation of that argument. The decline occurred 
in three cuttings between the middle of May and the third of 
July, yet the temperatures prevailing were not such as to warrant 
this, nor was there a noticeable decline in the precipitation. My 
observations agree with those of Frrepricu, that there are in white 
pine at least two periods of maximum growth. 
Irregularity of secondary growth in aerial parts 
A thorough treatment of the increase in growth in trees must 
necessarily be very comprehensive. The study in all its phases 
is a comparative one, for only by resorting to comparison can any 
fundamental rules of tree growth be formulated. A comprehensive 
study should therefore treat comparatively of the growth of (a) one 
individual during one growing season, (6) of one individual from 
season to season, (c) of different individuals in the same stand during 
one season, and finally (d) of different individuals not in the same 
stand. Data bearing on the first, second, and last phases of the 
