16 CRAIB—REGIONAL SPREAD OF MOISTURE IN Woop OF TREES. 
highest percentage, as indicated by the deepest shading, is now 
some little distance from the actual centre. As compared with 
the preceding plate, it will be noticed that the area bounded by 
the minimum near the outside and the sudden rise near the 
centre no longer shows a gradual increase inwards, but is broken 
up into a series of zones of secondary maxima and minima, with 
percentages, however, nowhere above 80. 
By January (Plate CLIl—which again represents the mois- 
ture distribution in a transverse section from mid-bole) condi- 
tions have been considerably altered, as shown by the very 
different appearance of the diagram. The dominant yellow 
(61-80 per cent.) is now replaced by grey and black (81-100 per 
cent.). The radiation of the moisture outwards from the centre 
has resulted in the very centre being below 80 per cent. (yellow), 
in the red zone (over I00 per cent.) being very much reduced, 
and in the larger yellow (61-80 per cent.) area of the previous 
two plates being now mostly grey to black (81-100 per cent.), 
the two larger 81-100 per cent. areas (grey to black) being separ- 
ated by a zone of yellow (61-80 per cent.) in the middle. The 
extreme outside has here a slightly lower moisture percentage 
than the corresponding region in December, and, as in the re- 
maining plates (CLIII, CLIV), shows an increase inwards 
instead of a decrease, as in Plates CL and CLI. 
The diagram for February (Plate CLIII), illustrating in the 
same way the distribution of moisture at mid-bole, shows that 
in the interval the radiation of the moisture outwards from the 
centre has continued. This diagram bears the same relation- 
ship to Plate CLII that Plate CLIT does to Plate CLI. Whereas 
in Plate CLII the bulk of the moisture was still not far from 
the centre, this central maximum is decreasing, and the moisture 
is reappearing as 2 maximum towards the periphery. For the 
first time we find red (over 100 per cent.) appearing in the 
outer region. 
In the diagram for the moisture distribution in a transverse 
plane at mid-bole in March (Plate CLIV) we find that the hori- 
zontal spread has now gone so far that we have really almost 
the reverse of the conditions depicted for October (Plate CL). 
The lowest percentage recorded here is in the centre, which is 
below 60 per cent. (blue). Excluding the youngest wood, we 
had in October a gradual increase inwards from 60 per cent. to 
80 per cent., and then a sudden increase from 80 per cent. to 
well over 100 per cent. in the very centre, whereas here, in March, 
we find a gradual increase outwards from below 60 per cent. 
at the very centre to 80 per cent., followed by a more marked 
increase from 80 per cent. to over 100 per cent. From this 
zone of over 100 per cent. (red) there is a sudden decrease to 
