1915) BROWN—PINUS STROBUS 207 
that the greatest increase would be in cutting II. However, as 
this was 30 feet above the ground, it is quite possible that the tissues 
there had not yet experienced the increase in temperature due to 
the rise of soil water in the trunk. 
The present investigation gives no reliable data as to where the 
first phloem activity was manifest. It had occurred throughout 
the tree on March 29, 1913. The awakening of growth began in 
this one specimen before the first of April and was not accompanied 
by cell division. Soil water was apparently largely instrumental 
in its inception. 
If we refer again to table B for the data for April 12, 1913, 
two weeks later, we may draw the following interesting conclusions. 
The greatest diameter increase at this time is in cutting II, where 
it has been over roo per cent. In other words, the ascending soil 
water may have reached the point of greatest growth (because the 
previous year’s ring was widest here) and caused a rapid expansion 
of the tissues. In cuttings III and IV we find an apparent reversal 
of the foregoing conditions. Cutting III has increased only 11 per 
cent during the same period, while in cutting IV we find the increase 
has been 26 percent. This may be ascribed to two causes, either one 
or both of which may be responsible. While the increased tempera- 
tures may have prevailed longer in IV than in III, the amount of 
reserve food material available was not as great. As a result, 
growth in cutting IV may have been retarded more than it was in 
cutting III; or cell division may have occurred in some of the cut- 
tings and upset the equilibrium. Careful counts were made to 
find the number of cells in the cambium and last formed phloem 
in all four cuttings of March 29 and April 12. While slight differ- 
ences occurred, these were not such as to warrant the conclusion 
that cell division had taken place between the two dates. The 
changes which occurred between March 29 and April 12 were 
due solely to enlargement of cells already present. We must 
infer then that the apparent contradictions of the figures in table B 
are due to differences of available food in different parts of the tree. 
Cell division had begun in tree I by April 26. At this time the 
activity was manifest in cutting I (table C). Here some 8-12 
tracheids and 2 or 3 new sieve tubes were already formed. Wall 
