439 
Williamson .— The Origin of ‘ Golden ’ Oak. 
chains. These were measured and found to be 3-4 4 by 2-3 fi, whilst those 
on hyphae growing out of the wood were 3*5-5 ^ by 2 * 5 ~ 3‘5 4 he slight 
difference in size may be due to the fixing and softening process the wood 
underwent prior to sectioning. 
Text-fig. 4. Lumen of wood-vessel showing pits, hyphae, and chains of conidia. x 500. 
Production of Yellow Substance. 
(a) In the Wood. 
Reference has already been made to the glistening yellow globules 
seen on hyphae in vessels of the wood. The same phenomenon occurs in 
fibres, vessels, and wood parenchyma seen in microtome sections. The 
hyphae in a cell may be studded with roundish small masses of a substance 
which may retain a yellow colour or may be stained red or yellow-red with 
safranin. Sometimes only one hypha in a cell will have this appearance. 
In other stages the substances will take the form of an irregular mass com¬ 
pletely covering a portion of the hypha. Where this substance is present in 
quantity the hyphae are often somewhat disorganized, and refuse to take up 
the light green stain taken by normal living hyphae. Instead they are often 
stained dark red by safranin. In one cell may be found hyphae staining 
light green, some disorganizing hyphae staining red, and irregular masses of 
a somewhat refractive substance which may or may not stain red with 
safranin. Finally cells are found which are completely filled with a yellow 
or red yellow substance in which it is sometimes possible to see broken 
mycelium (PI. X, Fig. 3). 
In transverse section infected oak shows refractive contents in the 
medullary rays, wood parenchyma, fibres, and even lining the vessels (PI. X, 
Fig. 1). These refractive bodies sometimes have a crystalline appearance, 
in other cells they are more granular in structure, and again it may not be 
possible to make out any definite structure at all. They vary in colour, 
being yellow generally, tangerine, or red-brown to brown occasionally. In 
transverse section these substances appear to occur in islands of cells sur¬ 
rounded by areas of comparatively empty cells, and this corresponds with 
