Fischer .■ — The Biology of Ar miliaria mucida , Schrader . 517 
growing in clusters (PI. XXXVII, Figs. 1 and 2) ; gills white, rounded 
behind, and broadly adnexed with a line-like decurrent tooth; stipe 2 to 
5 inches long, rather slender, but thickened at the base ; white, but base often 
with sooty squamules, rigid, stuffed ; ring near apex of stipe, white tumid ; 
spores elliptical, very shiny, 14 to 16 by 8 to 9 /x. 
Massee adds: ‘Very variable in size. Readily known by the very 
shiny pileus, which is usually whitish, but sometimes sooty or olive brown. 
Solitary or caespitose.’ 
It may be added that there are three vulgar names for this fungus in 
England : ‘ Beech Tuft,’ ‘ Beech Agaric/ and ‘ Clammy Armillaria.’ 
The descriptions by all other authors that I have consulted agree with 
that given above, with the exception of the statement as to the shape of the 
spores. Brefeld (2) refers to them as ‘ . fast runden Sporen/ and 
Patouillard (19) figures them spherical or nearly so. This discrepancy is to 
be explained in the same way as M finch settled the controversy between 
Moller and Malenconvie as to the shape of the spores of Mendius lachry- 
mans (17). Mfinch showed that those spores when quite dry are collapsed 
and boat-shaped, but swell out when moistened, though only by the breath, 
to an oval outline. I find the same phenomenon in the case of A . mucida , 
and that when moist the spores are almost perfectly spherical with a small 
insertion papilla and granular contents (Figs. 3 and 4), with an average 
diameter of 14 /x. The utility of this adaptation for dispersal is obvious, for 
the convexity when dry, coupled with the lightness due to absence of water, 
gives a better prospect of transport by wind. Dr. Mfinch himself showed me, 
a similar process with the spores of other fungi, among them one or two 
Ascomycetes. It seems probable that it occurs in most, if not all, fungi 
with smooth-walled spores that depend on wind for dispersal. 
Subject of the Investigation. 
The object of this inquiry was threefold : — 
1. To trace out the life-history of the fungus, at the same time 
determining its true nature — parasitic or saprophytic. 
2. To investigate its action on the wood. 
3. To suggest appropriate preventive and remedial measures. 
Each of these three will be dealt with separately and in the above 
order. 
I. Life-History. 
Methods. — The fruit bodies from which all the cultures were started 
were obtained from beech trees in Windsor Park on November 18 and 27, 
1908. On the second occasion I took a sterilized Petri-dish with me, and 
one sporophore was placed directly in it. The spores shed on the 
N n 2 
