14 CRAIB—REGIONAL SPREAD OF MOISTURE IN WOOD OF TREES. 
to not a few points of scientific interest. The leafless periods 
in the deciduous tree’s life-history are usually referred to as 
the dormant periods. The aptness of the term “ dormant ”’ 
cannot be questioned, but when it is used, as it often is, to 
convey the meaning of inactivity it is quite wrong. Can these 
activities of the dormant period be explained on purely physical 
grounds? Why the recurring wave-like shape of the graphs ? 
What part does the water which is involved in starch-hydrolysis 
play in the results as given? Why the extremely low moisture 
percentage in March of the younger two years’ wood, with such 
large percentages just behind that region ? Since I first became 
cognisant of these winter activities in Acer I have wondered 
whether they may not help us to understand better the reasons 
for the plan, and more especially the arrangement of the various 
pits on the different tissues. Up to now explanations have 
always been looked for in the leaf-bearing state. Is their chief 
function to control summer or winter movements? Or do they 
function equally in both ? 
In conclusion I wish to express my indebtedness to those 
who have helped me throughout this work. Professor Balfour, 
F.R.S., Regius Keeper, Royal Botanic Garden, has more than 
encouraged me to proceed with the investigations by the 
very liberal way in which he has placed at my disposal any 
available material which would aid the investigations. To 
Mr R. L. Harrow, F.R.H.S., Head Gardener, Royal Botanic 
Garden, I am also deeply indebted for the painstaking way in 
which he carried out the details of felling and other operations. 
Mr Spiers (of Messrs Souness & Spiers) has very kindly given 
immediate attention to the sawing off of the transverse cuts of 
several of the trees. To my colleague, Mr H. F. Tagg, F.L.S., 
I am also indebted for his very helpful criticism, whether con- 
structive or destructive. To Miss L. Snelling I owe the prepara- 
tion of the original coloured drawings of Plates CL-CLIV. 
LIST OF PLATES (CL-CLIX). 
Illustrating Mr Craib’s paper on Moisture Spread in Acer Pseudop/atanus. 
PLATE bee .—Average moisture distribution in bole in Orta. 
Dec 
cea ”” ” mber. 
cLIl. ig re a i hay 
CLITA ae .. ee ngshigsh 
CLIV, 
CLV.—Moisture distribution shatnghott trunk in October. 
o, T. 
> ” Pry a” January 
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