44i 
Williamson.—The Origin of ‘ Golden ’ Oak . 
Beside the yellow substance in the infected oak there occurred in 
certain cells, generally in small groups, dark granular masses. These were 
found in normal heartwood as well as in infected wood, and their distribution 
did not appear to be related to the hyphae at all. These patches appear to 
be slightly more numerous in the infected wood, but apparently their 
occurrence was not sufficiently great to cause any darkening in the colour 
of the wood. The dark substance was insoluble in hydrochloric, nitric, and 
acetic acids, but soluble in strong potash. Its nature was not discovered. 
This substance was noted in ‘brown ’ oak by Professor Groom. 
(b) In Culture Media. 
It has been found that, when grown on prune agar, malt agar, potato 
glucose agar, and synthetic starch agar, the fungus produces roundish 
refractive yellow or brown bodies. These bodies are very noticeable among 
the aerial hyphae. They are larger than the hyaline spores as a rule and do 
not dissolve in alcohol, water, or chloroform, and do not stain with iodine, 
Sudan III, Scharlach red, or alkannin. In fact they behave in the same 
way as the yellow substance produced in wood. Cultures on potato mush 
agar and on a synthetic sugar medium produce globules of yellow viscid 
substance of somewhat the same nature. 
The yellow colour does not extend to the medium in any of these 
cases. The only exception to this is oak-sawdust agar (4 per cent, or 
10 per cent, sawdust) infected with E. catenulata , where yellow coloration 
of the medium begins to show after three to four weeks’ growth. It maybe 
that this is the only medium possessing the requisite properties that result 
in the production of the yellow colour in the wood. 
The Action of the Fungus on the Cell-wall. 
A certain amount of splitting of the middle lamella is visible in sections 
cf infected wood, but it has not been possible to prove this to be due to 
fungal action. One case was noted in which a hypha was growing along 
such a split between two cells, but it is doubtful whether this was more than 
accidental. The splitting in sections may be due to some slight weakening 
of the tissue by the fungus, or by the process of softening, making it more 
susceptible to the action of the knife. 
The fungus passes from cell to cell through the pits, and no case of any 
other method of passage was found. There is no evidence to show whether 
the hypha pierces the middle lamella of the pit or excretes an enzyme to 
dissolve it. The fungus is capable of growing on and using up soluble 
pectin, and may possibly have some action on the middle lamella. 
Many tests were made to see if any delignification of the cell-wall by 
the fungus occurred, but none was observed. The wall region just round 
