In Fig. [32] are shown two buttons of the size when they are just ready to break through the soil. They appear mottled with dark and white, for the outer layer of fungus threads, which are dark brown, is torn and separated into patches or scales, showing between the delicate meshes of white threads which lie beneath. The upper part of the button is already forming the cap, and the slight constriction about midway shows the lower boundary or margin of the pileus where it is still connected with the undeveloped stem.
At the right of each of these buttons in the figure is shown a section of a plant of the same age. Here the parts of the plant, though still undeveloped, are quite well marked out. Just underneath the pileus layer are the gills. In the section one gill is exposed to view on either side. In the section of the larger button the free edge of the gill is still closely applied to the stem, while in the small one the gills are separated a short distance from the stems showing "gill slits." Here, too, the connection of the margin of the pileus with the stem is still shown, and forms the veil. This kind of a veil is a marginal veil.
Figure 34.—Coprinus comatus (natural size). This one entirely white, none of the scales black tipped.
The stem is hollow even at this young stage, and a slender cord of mycelium extends down the center of the tube thus formed, as is shown in the sections.
The plants are nearly all white when full grown. The brown scales, so close together on the buttons, are widely separated except at the top or center of the pileus, where they remain close together and form a broad cap.
A study of the different stages, which appear from the button stage to the mature plant, reveals the cause of this change in color and the wide separation of the dark brown scales. The threads of the outer layer of the pileus, and especially those in the brown patches seen on the buttons, soon cease to grow, though they are firmly entangled with the inner layers. Now the threads underneath and all through the plant, in the gills and in the upper part of the stem, grow and elongate rapidly. This pulls on the outer layer, tearing it in the first place into small patches, and causing them later to be more widely separated on the mature plant. Some of these scales remain quite large, while others are torn up into quite small tufts.
