Carpophore of some Agaricaceae . 685, 
pileus. Later the palisade tissue spreads inwards to form the primordium 
of the hymenium. 
Some time ago I collected material of a number of Agarics in order to 
determine their mode of development. A few of these have now been sec¬ 
tioned, and in the present note I have brought together the photographs of 
these sections and have added a few words of description. 
The great difficulty in studying the development of the carpophore of 
these Fungi, when growing in the open, usually lies in obtaining sufficiently 
young stages. In the case of Hypholoma fascicnlaris (Huds.), however, no 
trouble is experienced in finding all stages of development from the youngest 
rudiment to the mature fruit-body. 
In the earliest stage the primordium of the carpophore consists of 
a mass of narrow, closely packed, much interwoven hyphae, which for the 
most part take a clearly marked longitudinal course. Over the surface the 
hyphae are broader in diameter and more loosely arranged. This layer of 
superficial hyphae constitutes the universal veil. In Fig. 1, PI. LI I, three 
young fruit-bodies at this stage are seen developing side by side. 
Fig. 2 represents a slightly older carpophore rudiment. It will be 
noticed that the body has elongated considerably and that it now shows the 
first signs of a differentiation of its parts. Near the apex a cup-shaped 
layer of hyphae has become conspicuous in consequence of the deeper stain 
which it takes. This layer constitutes the primordium of the pileus, the 
‘ couche pileogene ’ of Fayod. The hyphae which compose it appear to be 
richer in protoplasm than their neighbours ; they do not assume, in this 
fungus, a palisade arrangement such as Fischer described in Armillaria 
mitcida , but on the contrary they tend rather to run transversely, so that 
their course is parallel with the surface of the ‘cup’ which they form. 
The layer of deeply staining hyphae increases in thickness and then 
spreads inwards, so that the edges of the ‘ cup ’ become incurved towards 
the centre of the young carpophore. This incurved and somewhat thickened 
area of the deeply staining layer of hyphae forms the rudiment of the 
hymenium (Fig. 3). In the next figure (Fig. 4) a slightly older stage is 
represented. 
In the section of the fruit-body here represented there are to be seen 
the first signs of the loosening of the tissue just below the primordium of 
the hymenium. The hyphae in this locality cease to keep pace with the 
growth of the rest of the carpophore. In consequence there is first a loosening 
of the tissue below the hymenial rudiment, and a little later an actual cavity 
is formed there. This cavity is the gill cavity. An early stage in its forma¬ 
tion is shown in Fig, 5. In this photograph we can distinguish the different 
parts of the carpophore: the universal veil, the pileus, the stipe, the hyme¬ 
nium, the gill cavity, and the marginal veil. In slightly older fruit-bodies we 
find that the whole structure, and more particularly the pileus, is broadening 
