395 
Groom .—‘ Brown Oak ’ and its Origin. 
normally appears. Trees with a maximum diameter of trunk of 12 inches 
frequently contain such wood, which is to be seen in individuals whose 
maximum estimated age was twenty years. 
* Brown-oak ’ trees in relation to site. Of oak-trees growing close 
together some may be normal, and others may be ‘ brown-oak 5 trees. For 
instance, at Farming Woods Park, of seven oak-trees close together, only 
one had ‘ brown oak 5 ; whereas in a small wood at Stanmore in Middlesex 
the majority of oak-trees had thoroughly brown heart-wood, others had 
their heart-wood brown to a slight extent, and yet others were quite 
normal. 
Previous Hypotheses as to the Cause of the Production 
of ‘Brown Oak 5 . 
Up to the present the cause of the production has been unknown, but 
three hypotheses have been put forward assuming that it is: 
(i) Due directly to some chemical body locally abundant in the soil. 
(ii) Due to incipient decay. 
(iii) A mere sport . 
(1) The chemical hypothesis not only has no evidence in its favour, but 
is rendered improbable by the facts concerning the occurrence side by side 
on the same site of normal and ‘ brown-oak 5 trees, and concerning the dis¬ 
tribution of ‘ brown oak ’ in the individual tree, and especially those cases of 
its unilateral or discontinuous distribution in the trunk. The chemical 
constituent frequently suggested is iron. Published analyses show that 
iron may be feeble or abnormally abundant in the wood, and yet this may 
be normal. An analysis conducted in the Chemical Laboratory of the 
Imperial College also shows that the amount of iron in ‘ brown oak 5 does 
not necessarily exceed that in normal heart-wood. The following was the 
result of the analysis: 
Iron (as Fe). 
Ash. 
Normal heart-wood 
Brown ,, 
o*oi % 
o*oi % 
(2) Incipient decay has often been suggested as the cause of the 
appearance of ‘ brown oak \ Such a view seems to imply that the browning 
of the heart-wood is an early stage of a process which culminates in the 
rotting and disintegration of the affected wood. Calculated to arouse such 
a suspicion are the following facts: Freshly felled ‘brown-oak’ trees often 
show the brown heart in a condition of decay, or the trunk partly hollow. 
Occasionally, at the base of such trees, the heart-wood up to a height of 
from 3 to 6 feet is converted into a mass of wood rendered white by decay, 
while above this is firm and hard typical ‘brown oak 5 . Finally, an inter¬ 
esting and significant fact is mentioned by Mr. Alexander Howard, namely 
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