394 BOTANICAL GAZETTE [NOVEMBER 



some distance below the apical shoot, but in a period covering 19 

 days gradually spread upward and was in progress in the apical 

 shoot on May 4, 1910. 



Cuttings of May 4 corresponding to figs. 7-9 were not photo- 

 graphed. Examination revealed the fact, however, that growth 

 was in progress throughout the basal portion of the trunk on that 

 date, and had progressed to a greater extent than was evidenced 

 on April 15. 



From the above investigations it follows that growth was in 

 progress throughout the main axis of the tree on May 4, while 19 

 days previous it was not in evidence in either the apical portion or 

 the base. If R. HARTIG is right in his assertion that growth is first 

 manifest in the branches, Pinus rigida is surely an exception to the 

 rule. MER'S investigations on young trees are in accord with 

 HARTIG' s, so here likewise growth in Pinus rigida appears to pre- 

 sent an anomaly. That HARTIG is right in his assertion that cam- 

 bial activity proceeds from the base of the crown downward, 

 investigations on trees A , B, and C seem to give convincing evidence. 

 Cambial activity was already in progress on both sides of the base 

 in trees B and C on April 27, while both cuttings in tree A on that 

 date appeared to be in the resting condition. This is explained in 

 that the trunk of tree B was better illuminated below than that of 

 tree A, while tree C was but 25 years old. But at this date growth 

 must have been in evidence in the upper portions of tree A, and 

 the only reasonable hypothesis is that it had not yet reached the 

 base, owing to poor insolation, thick bark, and age of the tree. 



Growth in lateral branches 



With a view of adding something further of value to the manner 

 of growth procedure in Pinus rigida, investigations were also car- 

 ried on upon certain of the lateral branches. Cuttings were taken 

 from each year's growth until the main axis was reached. Then 

 incisions were made 20 cm. above and a like distance below the 

 point where the branch joined the main axis. Growth in the 

 branches followed the same rule as in the main axis. It commences 

 some distance back of the apical shoot and spreads gradually in 

 both directions. Time of awakening in the apical shoots of the 



