8 
FETCH : 
which are infiltrated into the sound wood immediately in 
advance of the fungus. 
The action of the mycelium of Lentinus similis on the ^ 
wood appears to be identical with that of Siereum hirsutum 
as described by Ward (13). The wood is attacked 
from the interior of the cell towards the middle lamella, 
being first delignified and then consumed. The most notable 
difference lies in the selective action of the fungus, the 
fibres being delignified earlier than the medullary rays or 
the vessels. 
One fact already recorded appears to conflict with the 
finding that the fibres are first destroyed, i.e., the formation 
of furrows on the pseudo-sclerotium, in some cases, along 
the zones which contain the larger vessels. This apparent 
contradiction is explained when the furrows are examined 
carefully. It is then seen that the ends of the vessels project 
slightly above the general level at the base of the furrow 
(which is about 0*25 mm. deep), and that the furrow is due 
to the more advanced destruction of the fibres surrounding 
the vessels. 
But the special feature which appears to make the case of 
Lentinus similis worthy of record is the reservation of certain 
regions of the wood which is attacked by the fungus as storage 
tissue and base for the development of sporophores. Nearly 
the whole of the wood is quite destroyed, only the delignified 
remains of the medullary rays and vessels being left. But 
in some regions the wood is only lightly attacked, some layers 
of the walls being removed, but more than sufficient left to 
maintain the appearance, structure, and solidity of ordinary 
wood. These parts are filled with the h5rphæ already described, 
and from them the sporophore subsequently arises. 
I have not been able to determine that any further change 
occurs in the woody skeleton of the pseudo-sclerotium when 
the fructification develops. It would seem ' probable that 
the fructification is developed solely at the expense of the 
* storage hyphæ, and that the latter do not further attack the 
wood. The question is somewhat indeterminable, as the 
isolated pseudo -sclerotia are attacked by other fungi, as well 
as by bacteria and insects, in the field. 
