686 
Beer.—Notes on the Development of the 
out laterally. This can be seen by comparing Fig. 6 with Fig. 5, PI. LII. 
At this period of the development the hymenial layer is composed of a large 
number of narrow hyphae, densely filled with deeply staining protoplasm, 
and arranged very regularly and closely together side by side over the 
whole hymenial surface. The marginal veil can now be very clearly dis¬ 
tinguished, and it will be seen that it is composed of the neutral tissue 
lying just outside the gill cavity and within the universal veil. About this 
time or slightly later the stipe shows a differentiation into medullary and 
cortical regions. The former is composed of loosely arranged hyphae which 
stain very lightly, whilst in the cortical area the hyphae are more closely 
arranged and stain more deeply. The gill cavity continues to enlarge as 
the carpophore grows and the hymenial surface increases in area (Fig. 7). 
The gills are next developed as a series of down-growths from the hymenial 
surface (Fig. 8). 
The further history of the fruit-body is largely that of the expansion 
of its parts. The increased growth of the lower surface of the pileus and of 
the gills at length leads to the rupture of the marginal veil, which is left in 
the older carpophore as a fringe to the edge of the pileus and a darkened 
area upon the stipe. The stipe has in the meanwhile become hollow. 
Another Agaric which I have examined is Clitocybe laccatus (Scop.). 
Here also the first differentiation of the carpophore primordium con¬ 
sists in the demarcation of the pileus (Fig. 9). Just below the surface in 
the upper part of the elongated carpophore primordium a cup-shaped 
aggregate of closely interwoven hyphae appears and marks the rudiment of 
the pileus. Soon the rim or edge of the ‘ cup ’ grows inwards, and this 
internal extension of the closely arranged hyphae forms the rudiment of 
the hymenial layer. It will be noticed in Fig. 10, which represents this 
stage, that both pileus and hymenium have originated below the surface of 
the fruit-body, and that this is completely surrounded by a rather poorly 
developed, but still quite distinct, universal veil. The pileus now grows 
laterally, and in doing so soon ruptures the feebly developed universal veil 
(Fig. 11). The rest of the development of the hymenium takes place 
whilst this is exposed to the air and uncovered by any universal or marginal 
veil (Fig. 12). 
I have also cut a series of sections of the young fruit-bodies of Armil¬ 
iaria mellea (Vahl). These preparations do not bear out the account given 
of the development of this carpophore by R. Hartig; they are, on the con¬ 
trary, in general agreement with the description given by Atkinson of the 
mushroom and that given by Fischer of Armillaria mucida. 
The first differentiation of the previously homogeneous fruit-body con¬ 
sists in the appearance (in longitudinal sections) of two darkly stained 
patches lying a little way below the surface and near the upper end of the 
carpophore (Fig. 13). These darkly coloured patches in the longitudinal 
