6 CRAIB 
REGIONAL SPREAD OF MorsturE IN Woop or TREES. 
This fact shows quite conclusively that moisture distribution 
is not the determining factor in the selection of the optimum 
felling period. For, granted that winter is the period for resin- 
ous conifer felling, then the season in broad-leaved trees with a 
similar moisture distribution is that of the full-leaf condition. 
As stated in the earlier paper* other factors must be considered 
before a decision on the optimum-felling season can be given. 
But in the meantime the results from the Acer tree suggest a 
method of felling when the tree is in full leaf which might at 
least be given a trial. ‘The present practice is to cut off all 
branches almost immediately after the tree is felled. Instead of 
this let a tree be felled say in August and let the branches be left 
on until the leaves have flagged and are no longer transpiring. 
‘The result would be that the leaves would transpire the bulk of 
the water in the younger wood and we would have a trunk with, 
in the case of Acer, an almost uniform 60% of moisture 
throughout. ; 
Non-resinous Conifers have been represented in the experi- 
ments by Taxus, and in Taxus there are two points to be noted. 
‘There is here storage of moisture in the heart-wood. In this 
respect Taxus behaves as the broad-leaved trees, or I should say 
apparently so because the experiments were interrupted before 
the summer condition was examined. ‘The winter condition, 
however, is on the same lines as that of the broad-leaved trees. 
In Taxus there was noted a peculiarity not present in any of 
the other trees examined. In the cross section of the newly 
felled tree, three distinct areas can be recognised—central heart- 
wood, sap-wood on periphery, and separating these two areas a 
narrow zone of very pale wood (Plate CLXXXI). A very super- 
ficial examination sufficed to show that this narrow pale zone was 
much drier than either the heart-wood or the sap-wood and the 
final drying of the chips served but to emphasize the difference. 
The position of this dry pale-coloured zone immediately ex- 
ternal to the heart-wood suggested that it was some intermediate 
stage or the primary stage of the conversion of the sap-wood into 
heart-wood. To test the validity of this conclusion reagents 
were employed to find out the distribution of tannin in this zone 
and in the neighbouring heart-wood and sap-wood. 
Five tannin tests were used :—Osmic Acid + Hydrochloric 
Acid; Ammonium molybdate in Ammonium chloride solution ; 
ae chloride in Ether ; Potassium dichromate ; and Ammonium 
chloride. 
Heart-wood responded readily to the various tests as also did 
the half of the white zone next to the heart-wood, but the white 
zone gave no reaction in the part next to the sap-wood. These 
* Notes Roy. Bot. Gard. Bdin., vol. xi. No. LI. p. eeg = ca 2 
