397 
Groom.—‘Brown Oak ? and its Origin . 
felled ‘ brown-oak ’ trees. These came from different districts and were 
kindly supplied by Messrs. William Oliver & Sons, Messrs. Bradley, and 
Dr. Borthwick of Edinburgh. Two of the three specimens clearly showed 
wood in the process of conversion into ‘brown oak’. Those specimens 
proved that ‘ brown oak ’ is confined to the heart-wood, and is not produced 
by a change in the sap-wood, but first passes through the stage of being 
normal heart-wood . The first visible macroscopic change is a superposition 
of a yellow coloration on the normal colour of the heart-wood ; this is 
succeeded by a deepening of tint until the full-coloured brown stage is 
attained. With the naked eye in one specimen (Oliver’s) it was possible to 
see that the browning took place in the heart-wood along longitudinal 
strands, causing the wood to be brown-striped in longitudinal section, and 
dotted with brown islands in transverse section. 
Proof of the presence of a living fungus in the heart-wood 
during conversion into * brown oak ? e 
Pieces of the freshly felled wood were placed under running tap-water 
for 6-12- hours, and then placed above water in sterilized potato-dishes. 
From the exposed transverse section pure white fungal hyphae grew forth, 
almost exclusively from regions of the heart-wood, where conversion into 
‘ brown oak ’ was in progress. No hyphae came from the sap-wood. The 
Edinburgh specimen showed a solid core of ‘ brown oak ’, and practically 
no normal heart-wood ; the hyphae thus emerged from the periphery of 
the ‘ brown oak ’ in close vicinity to the sap-wood. But Oliver’s specimen 
showed in succession within the sap-wood a layer of normal heart-wood, 
one of brown-striped heart-wood, and a solid core of * brown oak ’. Accord¬ 
ingly the hyphae emerged solely from the periphery of the solid core, and 
also from the brown strips and peripheries of these in the striped wood. 
The whiteness of the colour of the hyphae (apart from their distribution) 
indicated that they belonged to a fungus or fungi living in the wood, and 
did not result from accidental infection. To confirm this, other specimens, 
after treatment with running water, were externally sterilized by means of 
an alcoholic solution of corrosive sublimate, and were subsequently washed 
with sterilized water: yet the result was the same. 
The white hyphae subsequently often became golden or tawny if they 
dried and remained sterile. Otherwise numerous green conidiophores soon 
arose, and resembled those of Penicillium. Later the conidiophores some¬ 
times assumed a warm-bronze tint. 
Artificial production of * brown oak \ 
In order to test the effect of the fungus on normal heart-wood, small 
cubical blocks of the latter were piled on top of one another in wide test-tubes, 
sterilized by steam, and infected by conidia of the fungus. The test-tubes were 
