38 



GROWTH IN TREES. 



The bast layer measured about 2 mm. in thickness throughout and 

 seemed fairly moist. The cork layer measured was light in color, pre- 

 sumably had been formed during the current season, and varied from 

 0.8 to 1 mm. in thickness. It was easily separable from the older 

 darker layers outside of it. The swelling of the bast was complete 

 in 2 hours in the acid, 4 hours in the alkali, and about 7 or 8 hours in 

 the glycocoll, while increase in water continued for nearly a day. The 

 swelling of the new cork in the acid went on at a very slow rate for 

 about 2 days, while it continued for 5 days in the alkali. It was com- 

 plete in the glycocoll solution in about 10 or 12 hours. 



FIG. 16. Dendrographic records of American beech (Fopus grandifolia) , showing only slight 

 daily variations in April, increases beginning late in May and continuing until September. 



Separate samples of cork and bast were taken from another place 

 on the trunk and sections were tested with the auxograph to ascertain 

 the water deficit of these tissues after a week in which growth had 

 come to a standstill, presumably on account of the dry, hot days. 

 These sections were swelled at 12 C. and the results are as below: 



