THE LAMELLAE IN COPRINUS MICACEUS 
sion of the subcuticular palisade cells which cover the pileus. In 
Coprinus tmcaceus we have from the very beginning a series of radially 
placed ridges consisting of a palisade of hyphal cells. The palisade 
cells observed here appear long before the so-called subcuticular layer 
of the pileus is differentiated. These young gill cells are rather long, 
their walls are thickened and stain somewhat more deeply than those 
of the cells of the pileus primordium (fig. 7). It is not easy to deter- 
mine whether these palisade cells of the young gills become the basidia 
directly. It is quite probable that further apical growth and branching 
lead to the definitive formation of the hymenium. 
Figure 8 represents a stage a trifle later. The figure shows a 
portion of a tangential section of a young button which is still cylin- 
drical or spherical or oblong in shape. The growth of the hymenial 
palisade layer is toward the surface and progresses proportionately 
to the increasing width of the primordium of the pileus. At the same 
time the length of the ridges increases by the formation of new palisade 
cells from above. It is very clear in this stage that the palisade cells 
do not enclose the edge of a gill but enclose the notch between two 
gills, that is, they form in section a V opening doward and not upward. 
Where the ends of the first formed palisade cells meet a small opening 
appears representing the beginning of a gill chamber of which a som'e- 
what later stage is shown in figure 9. The further development of 
palisade cells leads to the still further enlargment of the gill chamber. 
A longitudinal median section of a young gill chamber at this stage 
can hardly be made thin enough to show these relations clearly. 
Cross-sections of the forming gills are much more instructive. The 
tangential section shown in figure 8 is in a slightly older stage. Here 
we have a series of newly formed gill chambers. It is obvious at 
once that the spaces between the gills are not connected to form a 
single continuous annular cleft as described by Hoffmann, Atkinson 
and others. In reality we have here a series of radial gill chambers, 
one between each pair of lamellae. The hyphae of the trama of each 
gill run straight through into the stipe below and the pileus above. 
Figure 9 represents the young lamellae with the gill chambers between 
them on a large scale, showing the connections of the hyphae of the 
trama. The gill chamber is not altogether empty for some of the 
hyphae from the stipe seem to branch and grow into it as shown by 
Atkinson (1914^) for Armillaria mellea. Figures 10, 11, 12 represent 
hyphae from the trama and stipe in a somewl^at later stage ; two nuclei 
