On Polyporus squamosus Huds. 
2 77 
There was apparently a little more cellulose present in the 
steam-sterilised wood than in the fresh wood, chiefly in the fibres 
of the spring wood of each year but the distribution was rather 
irregular. This may have been due directly to the steaming, or in 
part to the prolonged action of water on the wood. 
The difference in wood, even slightly attacked by the fungus 
was obvious, and there was no doubt whatever, that a large amount 
of the delignification was actually caused by Polyporus squamosus. 
The effect of the growth of the fungus for 9 to 12 months on a 
block of Elm wood is as follows:— 
Just at the outside, for a depth of about T5 mm. the dis¬ 
integration is advanced, the wood being soft and falling to pieces 
when cut with a razor. Sections of this outer region show a des¬ 
truction similar to that observed in naturally attacked Elm wood. 
The vessels of the spring wood and a large number of fibres in their 
vicinity have completely broken down, but the autumn wood is only 
slightly attacked. The medullary rays are quite intact and serve to 
hold the bands of undestroyed wood together. 
On cutting transverse sections which include the peripheral 
regions, from the middle of a block, the progress of the action is 
evident. Such a section, treated with chlor-zinc-iodine, shows on 
the outside the lignified skeletons of the fibres, practically no 
cellulose being present. It is quite clear that the cellulose has 
been absorbed by the mycelium. Inside this zone the amount of 
cellulose present is very striking. Practically all the fibres of 
perhaps one half the year’s wood in each ring have their walls 
converted into cellulose, with the exception of a thin middle zone 
of the wall, the cavities being nearly occluded by this cellulose 
lining. Practically no cellulose was to he detected in the vessels, 
but these were the most rapidly destroyed and usually contained 
most of the hyphae, so that it is possible that the cellulose is used 
here as rapidly as it is formed. 
Considerable delignification was detected also in the centre of 
the blocks. Better conditions of aeration resulted in a more rapid 
penetration of the hyphae. 
The process of disintegration taking place here is on the whole 
similar to that described by Marshall Ward for Stereum hirsutum , 
the delignification taking place towards the middle lamella. 
In the case of Coniferous wood, on which a sparse mycelial 
growth was obtained, very little destruction had taken place. The 
medullary rays here were specially liable to attack, and in fact con- 
