1. Habit of growth.—In what situations do you find mushrooms growing? In what kinds of weather and at what time of the year are they most abundant? Take up a mushroom with a trowel, and carefully wash the earth from the lower part to see the tangle of white threads (called the mycelium), which is the underground part of the plant. See that several of these run into the bottom of the stalk. On the underground mycelium look for young mushrooms in the “button” stage. Look around, and try to get a series of mushrooms showing all stages from the smallest buttons to fully-opened specimens. 2. Structure.—Draw a side view (natural size) of a full-grown mushroom, showing the stalk and cap. Running round the stalk notice a ragged flap, called the collar. What is the height of the collar from the base of the stalk? Examine younger mushrooms to find what the collar really is. Notice that in young specimens a membrane or veil stretches from the edge of the cap to the stalk, and that as the mushroom grows larger this veil is torn away from the cap (Fig. 157), and remains as a ragged flap (the collar) on the stalk. In young specimens, therefore, the lower side of the cap is completely shut in by the veil, while in fully-grown ones it is exposed. 3. The gills and spores.—Cut the stalk across at the top, and make a drawing of the lower surface of the cap. Notice the radiating vertical plates (the gills), and their flesh-coloured or dark-brown tint. Be careful to show the exact arrangement of the gills in, say, a quarter of the drawing. Cut off the cap of a mushroom which has brown gills and lay it, gills down, on a sheet of paper; cover it with a tumbler to shield it from draughts, and leave it for a day. Then take off the cap (being careful not to smear it along the paper), and observe the radiating brown lines. On touching them, it will be seen [Pg 204] that the lines consist of fine brown dust. The particles of dust are spores. They have evidently fallen from the gills. 4. The source of the mushroom’s food.—What is the colour of the mushroom? Cut through the stalk and cap in various directions and notice the pure white “flesh” of the interior. Do you think it likely that the plant can obtain carbonaceous food from the air? Why not? Dry a mushroom and burn it carefully. Does it contain carbon? Where must the carbon have come from, if not from the air. Can you find any decaying vegetable or animal matter in the soil in which mushrooms grow? 5. Toadstools.—Carefully compare the common mushroom with other gilled fungi which look somewhat like it. Notice particularly the following characters: the colour, shape, and texture of the surface of the cap; the colour and arrangement of the gills; the proportions of the length and thickness of the stalk to the diameter of the cap; the presence or absence of a collar on the stalk; the presence or absence of a cup, or scaly swelling, at the base of the stalk.