It is a brown-black powder soluble in hydrochloric acid, chlorine being simultaneously liberated.
When a mushroom is perfectly ripe and the gills are brown-black in colour, they throw down a thick dusty deposit of fine brown-black or purple-black spores; it is essential to note the colour.
This pigment is usually intracellular, but may be found lying free in the intercellular substance, and is generally in the form of fine granules of a yellowish-brown or brown-black colour.
To summarize the characters of a true mushroom - it grows only in pastures; it is of small size, dry, and with unchangeable flesh; the cap has a frill; the gills are free from the stem, the spores brown-black or deep purple-black in colour, and the stem solid or slightly pithy.
The colour of the buck is a deep brown-black above, sharply marked off from the white of the belly.