44 2 Williamson,-—The Origin of ‘ Golden ’ Oak. 
the pits was particularly scrutinized and no cellulose reaction due to 'the 
fungus could be found. It was noted that, with the iodine-sulphuric acid 
test, the reaction for cellulose occurred wherever a wall had been broken or 
distorted or strained by the action of the knife or the pressure of the 
microtome holder. This made the test difficult to interpret, and great care 
had to be taken in observing the path of the hyphae and the walls in contact 
with them. The conclusion that the fungus has no power of delignification 
was reached. 
Source of Food jn the Wood. 
The fungus is growing in seasoned heartwood of oak. The food avail¬ 
able is the pectic substance of the middle lamella ; the pectic bodies, gluco- 
sides, tannins, cellulose, and lignin in the walls ; the tannin bodies in the 
medullary rays and wood parenchyma cells ; any starch or waste products 
which may have been contained in the cells and dried in the process of 
seasoning. The amount of food material is necessarily small, and the chief 
bulk would be comprised by the lignified walls and the tannin with glucosides 
and other impurities in the cells. The small quantity of the food is not 
a deterrent to the growth of E. catenulata , as the fungus can grow on media 
with minute quantities of salts only, on starvation media suggested by 
Coon ( 1 ), and even on dilute hydrochloric acid in distilled water. 
There is no evidence that the fungus is capable of delignifying the cell- 
walls, and it shows no appreciable growth on cellulose, so the lignin and 
cellulose are probably not utilized. Certain deductions as to its method, of 
nutrition in the wood may be made from the study of its behaviour in 
various nutrient constituents, an aspect which has already been dealt with in 
considerable detail elsewhere. 
The fungus has been shown to be capable of growth in almost pure 
soluble pectin derived from apples. Hence it is not improbable that the 
pectic bodies in the walls of the wood may supply a certain amount of 
nourishment. The middle lamella is not disorganized by the fungus, which 
seems to attack it only at the pits and that action may be physical, there¬ 
fore that lamella cannot be regarded as a source of food. 
Any sugar or glucoside would be readily used, as it has been demon¬ 
strated that E. catenulata grows freely on glucose and can invert cane 
sugar. 
This fungus can hydrolyse starch, but the quantity available is ex¬ 
tremely minute, being scattered sporadically in ray cells and wood 
parenchyma. It is able to grow to a certain extent in an acid medium con¬ 
taining no other source of nutriment. It is highly tolerant of certain acids 
(limits being pH i*i6 to pH 8 -2) and is probably able to utilize malic, citric, 
tartaric, and gallic acids. Any trace of gallic acid in the oak can be 
utilized. Growth also occurs in a solution containing from o-i to 2 per cent. 
