125 
Bulgaria polymorpha , Welt. 
focal lengths appear to be surmounted by a cross with arms 
at right angles to one another. As the walls became swollen, 
one arm disappeared, while the other became an elliptical 
slit which gradually broadened until it was roughly circular 
in outline. Hartig 1 figures a somewhat similar series of events 
in the case of oak-wood attacked by Thelephora perdix (Hartig), 
Stereum frustulosum (Fr.). 
Schulze’s solution, however, swells the walls of the elements 
to a considerable extent and so obscures many details. To 
obviate this I have used a saturated aniline-water solution of 
gentian violet and a saturated 5° P er cent, alcohol solution 
of Congo-red. The sections were stained from sixteen to 
twenty-four hours in gentian violet and then transferred 
directly to the Congo-red solution, where they were usually 
left for an hour and then dehydrated and mounted in Canada 
balsam. 
Tangential longitudinal sections of cultures a fortnight old 
were then for the most part stained an intense blue, except 
at pits where hyphae had passed through the walls. These 
pits were then marked by a sharply-defined, bright pink zone 
surrounding them, indicating that that portion of the wall had 
been delignified, and a cellulose basis staining with Congo-red 
remained. 
In the case of cultures a month old this action was very 
marked, and one could easily find, especially in the vessels, 
walls in which every pit was marked in this way. Moreover 
no hyphae passed through the majority of these pits, so that 
one has to assume the secretion of a delignifying enzyme in 
quantity by the Fungus into the wood-elements. The rings 
round the pits gradually increased in size and in time met 
one another, so that the surface of the wall was marked by 
a clear blue network with angular patches at the corners of 
the mesh-work, on a pink ground (Fig. 3 ). Ultimately these 
angular patches disappeared also and the whole surface was 
stained pink owing to the entire delignification of the wall. 
The corresponding appearances in transverse section were 
1 Hartig, Zersetzungserscheinungen des Holzes, p. 103, and Taf. XIII, 1878. 
