Some Colorado Mushrooms 
A 5 
the spores, it opens by a small rounded mouth at the extreme top of 
the plant. A mature dry specimen when suddenly pressed between 
the fingers, will give off repeated puffs of smoke-like spore dust and 
thus illustrates unusually well the origin of the common name of 
“puffball” applied to the plants of this character. 
GILL-BEARING MUSHROOMS (Agaracineae Agarics). 
The fungi composing this family are characterized by having 
the spore-bearing layer spread on the surface of thin, radiating 
plates or gills attached to the lower surface of a more or less ex¬ 
panded or flattened part, the cap or pileus. In the simpler mem¬ 
bers of this family, the pileus is shaped much like one of the valves 
of a clam shell attached by one edge to whatever the fungus is 
growing upon. In the more highly developed members the pileus 
is bell-shaped or inverted saucer-shaped and is raised upon a cen¬ 
tral stalk with the gills radiating from its upper end toward the 
margin of the pileus. When very young or in the button stage the 
pileus is mostly rounded in shape and the stem is very short, in 
which condition the whole plant is often egg-shaped. As the fungus 
is about ready to mature its spores, the stem rapidly lengthens lift¬ 
ing the pileus into the air, where it soon opens out and allows the 
spores to drop from the gills attached to its lower surface. 
The spores of the gill fungi are borne upon the ends of cells 
called basidia the same as in the puffballs. Instead of being enclosed 
by the outer walls of the fungus, however, they are exposed to the 
air as soon as the cap or pileus expands and are thus readily cast 
off and wafted away by the gentlest breeze. 
SPORE PRINTS. 
In order to identify with certainty the members of the gill 
fungi or agarics, it is necessary to know the color of the spores. 
While this can often be told by a careful examination of the gills 
which are usually powdered with the dustlike spores, it is deter¬ 
mined most surely by making a spore print. If the cap is carefully 
removed from the stem and placed gills down upon a piece of white 
paper and covered with a tumbler or bell jar, the spores will set¬ 
tle upon the paper and form a spore print (Figs. 12-13). This pro¬ 
cess may require from one-half to three or four hours, depending 
somewhat upon the freshness of the specimen. If the spores are 
white, they can hardly be seen except by looking across the paper. 
If black paper is used for those species which have white gills, the 
