PSEUDO-SCLEROTIA OF LENTINUS SIMILIS, &C. 3 
give ris© to the Lentinus sporophore. They are thus analogous 
to Sclerotia, but their framework consists of wood. It does 
not appear, therefore, to he unduly extending the idea of the 
term if we style them pseudo -sclerotia. The sporophore, 
apparently, always arises from such a pseudo -sclerotium ; 
when it has seemed to grow from a stump, it has been found 
on examination to spring from one of these bodies which lies 
practically free in the surrounding decayed tissue. 
Figure C shows that the selective action of the fungus in 
forming these pseudo -sclerotia is not correlated with any 
particular region of the wood. In that particular example 
the body of the maäs is composed of the outer wood of the 
stem,, but the radially projecting limb penetrated almost to 
the centre of the tree. On the other hand, the markings on 
the surface of the pseudo -sclerotia indicate a slightly more 
advanced destruction along the medullary rays and the 
annular zones which contain the large vessels. 
von Schrenck (11), in describing the destruction of the wood 
of Prosopis glandulosa by Polyporus texanus (Murrill) Sacc. & 
Trott., states that the fungus does not destroy the wood as a 
whole, but attacks only the heavily lignified groups of wood 
fibres. Although the wood parenchyma and the vessels are 
filled with hyphæ, they resist destruction almost completely. 
This he attributes to the high tannin content of both these 
tissues. The finding that tannin exerts a retarding influence 
on the development of certain fungi was published by the 
present writer (7) in dealing with Thielaviopsis paradoxa in 
1909, and it has since been extended to other species by other 
investigators. But it is evident that this cannot be invoked 
to explain the formation of the pseudo -sclerotia of Lentinus 
similis, since the latter may include elements of all the regions 
of the stem. 
Bough determinations of specific gravity, made from deter- 
minations of gross volume and weight, gave the following 
results. In normal Hevea wood from a tree twelve years old, 
taken midway between centre and circumference, the specific 
gravity was 0*66. A pseudo -sclerotium from Hevea wood, 
which had apparently not yet produced a sporophore, had 
a specific gravity of 0*65. A small pseudo -sclerotium 
