GROWTH IN TREES. 39 
These swellings were concluded at the end of 3 days, the course of 
enlargement being much as has been previously described. The 
record of the variation in size of the trunk during this period showed 
that the woody trunk made a daily variation practically equivalent to 
that of the entire tree. 
These results show that the cork in one instance was impervious to 
water and remarkably so to the other solutions. The bast, of course, 
takes up water readily and is easily penetrated by other solutions, 
especially the hydroxid and amino-acid. These results may be taken 
to indicate the possibility of some transpiration through the bark, 
although this matter was not tested, directly. On May 22 a dendro- 
graph was attached to a tree about 35 cm. in diameter, standing on 
the north-facing slope north of the laboratory, for the purpose. of 
Oct. 4 1920 
6PM BAM. 6PM. 6aM 6PM. Bam 6PM. 6AM BPM 6AM. 6PM 6AM 6PM. 6aM 
| a 
fis 30 192 
2 2 
JUNE 21 1920 
21 3 210 
i ee een | ba) [rset feet 
MAY 24 1920 
4 2 
™s a eee —, a ae 
Fia. 16.—Dendrographic record of Monterey pine No. 7, to show relative amount of variation 
in outer and inner parts of trunk. The record for the week beginning May 24 is for the entire 
trunk, the bearings being taken from an inner thin layer of cork. All other records are from 
bearings taken from the woody cylinder internal to that of 1918. Therange of the daily variation 
of the inner cylinder is seen to be less in the earlier part of the season and to decrease with the 
season, #8 shown in the record for the week beginning August 30. A slight increase was seen in the 
week beginning October 4. Variations are X 25 on a scale of 10 mm. intervals. 
measuring the relative expansion of the cork and cambium layers and 
of the wood. The plan was to attach the instrument to the tree entire 
and to obtain the record of the daily course of change, and then strip 
off the bark and growing layer and place the contacts of the instrument 
on the trunk itself. The trunk was seen to be undergoing daily 
equalizing variations with no growth in progress. Pine No. 6, a few 
meters distant, was still showing some accretion, but with a steadily 
lessening rate. 
