4 CRAIB—REGIONAL SPREAD OF MorsturE iN Woop or TREES. 
towards the centre—exactly the reverse of the March condition 
and further in the first May tree we have in the bottom cut a 
return of the three-wave graph. In short, comparison of the 
graphs of the bottom cuts for the first May tree (P]. CLXX XIII) 
and the January tree (P1. CLVII) shows that they are practically 
identical. Nor does the similarity of the results obtained from 
these two trees end here. There is a general resemblance 
throughout all the results as plotted for these two trees. 
Again, the second May tree shows results (Pl. CLXXXIV) 
comparable with those of the March tree (Pl. CLIX) but on a 
much smaller scale. Here there is once more the maximum 
moisture percentage almost on the outside, though that maximum 
is very much smaller than in March. Since then the first May 
tree resembles so closely the January tree in its moisture distribu- 
tion and the second May tree is comparable with the March tree, 
one may legitimately ask whether in the interval April-May 
(?March-May) the moisture does not go through the same move- 
ments on a reduced scale and at greatly accelerated speed as in 
the longer interval October-March. 
Again in the second May tree (Pl. CLX XXIV) there is in the 
uppermost two cuts a decided increase in moisture percentage 
towards the outside. This increased percentage is correlated with 
the fact that here growth has now commenced. 
The time relationship of bud-opening and the commencement 
of diameter increase is not the same for all trees. In the trees 
of Acer Pseudoplatanus examined growth began at the twigs when 
the buds were still closed, extended back along the branches to 
the trunk and reached a little way down the trunk only after the 
leaves were fully expanded. This was not the case in a speci- 
men of Quercus pedunculata felled in May when only at the top 
of the tree a few male inflorescences were showing and when not 
a single leaf was to be seen on the tree. Here a row of new spring 
vessels was already formed throughout the bole. In Acer 
_ Pseudoplanatus new wood was formed on the trunk only after 
leaf-expansion ; in Quercus pedunculata new wood was present 
throughout the trunk before the buds had burst. 
b. Full-Leaf Condition, August (Pl. CLXXXV). 
Interpretation here presents practically no difficulty. The 
transpiration current is represented by the higher percentages 
in the youngest wood and throughout most of the tree the whole 
central area has an almost uniform percentage averaging but 
slightly over 60. Probably in a tree of uniform growth the 
graph, excluding the transpiration current, would be a straight 
ene 
eH Bie deciduous Coniferae see under Coniferae. 
