GROWTH IN TREES. 27 
March 16, after which acceleration carried growth to a maximum rate 
in the last 10 days of April. The rate now slackened and growth 
ceased about June 1, with a total increase of 4.5 mm. in diameter. 
A rain on June 14 was followed by some growth in the following 
week, after a period of reversible alterations ensued. Not until late 
in July did a slight enlargement recur and a similar impulse was re- 
corded at the end of August (fig. 8). No further increase could be 
detected, but a shrinkage began on October 11 which continued until 
. 
SEPT. 20 19 
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Fia. 8.—Dendrographie records of Monterey pine No. 6, with no growth in week of March 1, 
1920, beginning growth in week of March 22-29, vigorous enlargement in week April 12-19 daily 
equalizing variations of wide amplitude in week of June 28-July 5, and reduced variations late in 
September. Variations X 5 on scale of 10 mm. intervals. 
the instrument was dismounted a week later. A total increase of 
5 mm. had been recorded. It is to be noted that the terminals and 
tips of the branches had made a growth of several centimeters when 
the observations were begun, and that such elongation must have 
started about two months prior to the increase in the trunk. 
Measurement of another pine (Pinus chihuahuana), on the slopes 
of the Santa Catalina mountains, an isolated range near the Desert 
Laboratory, gave a set of results under conditions different from those 
afforded by the indeterminate seasons of the coastal climate. A tree 
40 cm. in diameter, in the lower edge of the pine belt at about 2,000 
meters, was selected for observation. This location is characterized 
by a coarse granitic soil, winter and mid-summer rainfall; minimum 
air temperatures of 8° C. and summer maxima of 40° C. are of record. 
