1916] FoMEs OFFICINALIS (Vill.) 199 
FRUITING-BODY. 
The sporophore of Fomes officinalis varies considerably in form, 
from almost globular—characteristic of the first year’s growth—to 
ungulate or cylindrical or occasionally even fairly applanate, and it 
measures from 5-65 cms. in height. The maximum measurements 
indicate giant specimens among the fungi; Murrill” states that sporo- 
phores up to fifteen pounds dry weight have been found. The surface 
is anoderm, but soon becomes somewhat encrusted. Young fruiting- 
bodies, that is of one or two years’ growth are chalk-white in colour 
or slightly yellowish, but with age there may be a mottling of yellow 
and white, or more commonly of gray. The change is due to a darkening 
of the contents of filaments in the crust, a darkening that may. extend 
to the cell-wall and to the resinous secretions of the hyphae. 
The crust in older plants is more or less radially cracked or rimose. 
On the lower surface, each year a new layer of pores is added, varying 
from 5 to 20 mm. in thickness. Extending over a period of 45 years, 
the specimen illustrated in Fig. 1 shows an average annual accretion of 
12.5 mm. As the margin of each layer is convex, and the peripheral 
pores of the preceding layer are not covered by the new, the surface is 
strongly concentrically furrowed. The specimen recorded by Neuman’, 
65 cms. high, shows 70 strata or an annual accretion of more than 9 mm. 
The context is rather tough when fresh, but firm and quite friable 
when dry; but these textural characters are likewise true of the porous 
layers, due to the fact that after sporulation, hyphae grow down so 
as to completely fill up the pores, to such an extent that the latter lose 
their identity, and very soon context and porous layers are alike in 
texture, and distinguishable from one another only by a poorly-defined 
colour zone at the boundary of each stratum. The entire surface is 
so friable that it is abraded in handling, a chalky-like powder adhering 
to the fingers. The tubes are circular to angular, 3-4 to a mm. with 
thin and more or less laciniate and fragile walls, white at first, later 
discoloured. The spores are hyaline, smooth, ellipsoid, 3-4 4-5u; 
those of P. sulphureus are larger, 4-5 X6-7y. 
Structurally, the sporophore has proved to be of unusual interest, in 
part because of the extensive secretions of resin, and in addition because 
of the peculiarities of the organization of the context, and because of 
the discovery of chlamydospores, a secondary form of reproduction 
not frequent in highly-organized fructifications of any kind. 
The context consists mainly, except next to the pores, of unbranched, 
thick-walled threads about 3u in diameter, much like those of the 
mycelium, though rather coarser, varying from 1.5-4y4, and very rarely 
