CRAIB—REGIONAL SPREAD OF MOISTURE IN Woop OF TREES. 17. 
8o per cent., and then a more gradual decrease to almost 60 per 
cent. The zone occupied by this black, grey, and yellow colour- 
ing denoting the decrease from 100 per cent. to almost 60 per 
cent. would correspond roughly to the area between the mini- 
mum noted for October (Plate CL) and the outside. 
Plates CLI, CLII, and CLIII show intermediate stages in 
the moisture spread. Probably the best impression of what 
occurs in the way of moisture spread during the period under 
survey will be obtained from a comparison of the two extremes, 
as represented by the diagrams for October and March (Plates 
CL and CLIV respectively). The maximum region in October 
becomes the minimum region in March, and the minimum 
region of October becomes the maximum region of March: 
or, in terms of the colours depicted, red, indicating a moisture 
percentage of over 100, occurs in the centre of the trunk in 
October and in March only towards the periphery ; blue, 
indicating a moisture percentage of less than 60, occurs in the 
centre of the trunk in March, and in October it occupies a circle 
roughly about 5 mm. from the outside of Plate CL. 
Explanation of Graphs (Plates CLV-CLI). 
- Whereas the coloured plates have been designed to show 
the average moisture distribution as seen in a transverse plane 
at approximately the same level in the bole of each of the trees 
examined, the graphs drawn on mm. paper give the actual 
results of the various experiments, and show the state of the 
moisture distribution throughout the trunk at the selected 
levels. 
In each case metre distances above ground level are marked 
off vertically along the median line of the plate, and the centre 
line of each transverse cut examined is inserted in conformity 
with this scale according to its distance above ground level, 
as ascertained when the tree was felled. 
In Plate CLV each graph read horizontally gives the moisture 
distribution at that particular level from the youngest wood 
at the left-hand side of the plate to the centre of the trunk in 
the middle of the plate. In the remainder (Plates CLVI-CLIX) 
we have, read horizontally, the moisture distribution from the 
centre of the trunk in the middle of the graph to the outside of 
the trunk in two directions at the extreme right- and left-hand 
sides. 
The annual rings have been plotted horizontally (2 mm.= 
I year) and the moisture percentages vertically (1 mm.=2 per 
cent.), so that an upward tendency of the graph signifies an 
B 
