484 
FORKST AND STREAM; 
[June i8, i8gK 
young gills in the sections resemble tM'o eyelets. These 
have been covered over on the outside bj'- the mycelium 
growing downward from the cap, and upward from the 
stem, the ends of the thread interlacing to form a veil 
which extends all around the stem, covering the con- 
stricted portion at the junction of the stem with the 
button. If we cut across the button at this point the 
gills would show as a ring with the veil outside. 
As the plant grows all these parts increase in size, the 
gills extending downward by the growth of the myce- 
lium in radiating lines to form the plates. As the cap 
expands the veil is stretched and a cavity appears be- 
tween the free edges of the gills and the veil. If we now 
look at Figure D, which is from a photograph of the 
under side of two nearly mature plants, we can see the 
portion of the gill is termed the trama. Just outside of 
this, on either side, is a laj'er several cells deep of short 
cells termed the hymenium. From the cells of the hyme- 
nium are borne the club-shaped bodies which stand 
closely parallel in a layer on each surface of the gill. 
Each one of these club-shaped cells is termed a basidium 
(the latin work for club). Each basidium bears at its free 
extremity two slender processes which lend to the basi- 
dium a forked appearance. Each one of these processes 
is termed a sterigma (plural, sterigmata). Each sterigma 
bears a spore, which is a nearly rounded or oval body, so 
that each basidium in the common mushroom (Agaricus 
campestris) bears two sterigmata and two spores, while 
in a majority of the members of the group the basidia 
bear four sterigmata and four spores. 
lives here for several months, or in some cases for years, 
before developing the fruiting portion which is the 
"mushroom." This first appears as a minute rounded 
mass on the strands of mycelium. It grows in size to 
form a "buttom" with a stem. The young gills are 
formed by the mycelium growing downward in radiating 
ridges from the under side of the margin of the button, 
the gills at first being covered by a delicate veil of inter- 
lacing threads. As the pileus expands it bursts through 
the sod, ruptures the veil, when the characters of the 
fully formed mushroom appear. 
Lepiota naacina, Fr. 
The next mushroom, or toadstool, described here is 
one which occurs during the same season as the Agari- 
C. AGARICUS CAMPESTRIS. IJ AGARICUS CAMPESTRIS. 
Sections of "buttons" of difEerent sizes, showing formation of gills and veil covering them. Nearly mature plants, showing veil still stretched across the gill cavity. 
veil stretched over the gills from the margin of the 
pileus to the stem. Here we can see how delicate the 
texture of the veil is and how easily it is torn. During 
these stages the gills are pink in color except in the 
very youngest, when they are white, unless by some ac- 
cident the plant becomes old before the veil breaks. The 
cap now expands more and more, and the veil is rup- 
tured as shown in Figure E. The fragments of the veil 
are shown clinging partly to the stem and partly to the 
margin of the pileus, where the dripping tender fibrils 
lend a weird aspect to the specter-like plant as it lifts 
- its head from the sod at night. 
Because of the very delicate and fragile character of 
the veil, it does not in many cases remain clinging to 
the stem as a complete ring, and it is also in some cases 
quite evanescent. 
Sometimes the fibrils on the surface of the pileus are 
drawn into triangular patches which point outward, as 
shown in Fig. F. This gives a scaly appearance to the 
surface of the pileus. While in the ordinary form of this 
mushroom the surface of the cap is white, often the 
At maturity these spores easily fall away from these 
little forked processes (sterigmata) and give a dark 
brown coating to the objects on which they fall. The 
spores are purple brown in color, and as they mature 
their number on the surface of the gills accounts for 
the dark brown color of the latter. One can obtain what 
is sometimes called a "spore-print" of the under surface 
of the mushroom, or arrangement of the gills, by cutting 
off the stem and placing the pileus on white paper for 
a few hours. It should be placed where there are no 
drafts of air and covered with a bell jar or other closely 
fitting vessel to avoid the shifting currents of air, since 
the spores are so light they would not fall perpendicu- 
larly, but drift and thus confuse the print. 
Brief Description of Agaricus campestris. 
The common mushroom (Agaricus campestris) grows 
in lawns, pastures and similar places. It averages S to 8 
cm. (2 to 3in.) in height, the pileus being 5 to 12 cm. in 
diameter. 
Pileus. — The cap or pileus is convex or more or less 
cus campestris (common mushroom), and in similar lo- 
calities, i. e. in lawns, pastures, etc. It is known as 
Lepiota naucina, the short stemmed parasol, or smooth 
Lepiota. Because of this similar seasonal and local oc- 
currence it might at first be taken for the Agaricus 
campestris, especially since the plant is about the same 
size, is usually white or light tan, and possesses an an- 
nulus. The gills, however, are white from the youngest 
stages to maturity, only becoming pinkish when very old, 
and drying a light brown or dirty pink. 
A photograph of this plant as it occurs in lawns is 
represented in Fig. G. On looking at the gills of a fresh- 
ly growing plant one would readily distinguish it from 
Agaricus campestris, because of their white color. The 
spores of this plant are white. The color of the 
spores is one of the most constant characters which 
the members of the mushroom family possess, and 
in studying these plants some of the spores should be 
caught on white paper for the purpose of determining 
their color. Fig. H represents four different sizes and 
stages of this Lepicta. In the plant at the left the veil 
E. AGARICUS CAMPESTRIS. 
Under view of two plants just after rupture of the veil, fragments of the latter clinging 
both to margin, of pileus and to stem. 
V. AGARICUS CAMPESTRIS. 
Plant showing loose fibrils on surface of pileus drawn into triangular scales. 
fibrils on the surface are brownish. In one form of the 
plant the triangular scales are dark brown, and give it 
a quite different aspect. This dark scaly form some- 
times appears early in the spring. 
If we note the position of the gills carefully, as we can 
by referring to the photograph (repr*>.sented in Fig. B) 
of the under side of the pileus, it will be seen that they do 
not quite reach the stem and are rounded at the inner 
end. They are thus only attached by their upper edges 
to the surface of the pileus. Between the longer ones 
are shorter ones which reach, some only a little dis- 
-tance from the margin of the pileus, while others reach 
half or two-thirds the way to the stem. The space is 
thus used to good purpose, and the entire under surface 
of the pileus is crowded with thes« gills or lamellae. 
The surface of these gills forms what is termed the 
fruiting surface of the mushroom, or hymenium. The 
structure of the gill is quite specialized, and here we find 
parts which are characteristic of the great group of plants 
to which the mushroom belongs. If we cut very thin 
slices or sections across a few of the gills, and mount 
them in water under a thin cover glass for examination 
with the microscope, we shall see revealed these pecu- 
liarities. Through the center of the gills the mycelium 
continues down from that of the pileus. This middle 
expanded, the surface being nearly smooth, or more or 
less silky hairy, these fibrils sometimes being collected 
into triangular scales. The color of the surface is usually 
white, but varies to light brown, while the flesh is white. 
Gills. — When the plant is very young the gills are first 
white, but soon become pink, and later purple brown or 
dark brown from the numerous purple colored spores 
on the surface. The gills are free from the stem, and 
rounded on their inner ends. 
Veil and Annulus. — The veil is thin, white, silky and 
very frail. As the pileus expands the veil is stretched 
and finally torn, when it clings as a thin collar or ring 
(annulus) around the stem, or fragments dangle from 
the margin of the pileus. As the plant becomes old, 
the annulus shrivels up and becomes inconspicuous. _ 
Stem or Stipe.— Tht stem is white, nearly cylindrical, 
or slightly tapering at the lower end. It varies from 
3 to 8 cm. long and i to 2 cm. in diameter. The flesh is 
solid, though less firm at the center. 
Growth of the Mushroom. 
The mycelium in the form of delicate threads or stouter 
strands (called spawn) lives in the soil, absorbing in 
solution certain of the substances of decaying vegetable 
matter, which it appropriates for growth and increase. It 
still covers the gills. In the next one it has broken away 
from the margin of the pileus and forms a collar around 
the stem. In the third the pileus is still more expanded. 
We see here that the gills are free from the stem. The 
general characters, then^ with the exception of the color 
of the spores, are the same as those of the Agarieus 
campestris. 
This distinguishing feature, the different color of the 
spores, is regarded as such an important one that it is 
used to separate genera, and so this plant is placed in 
the genus* Lepiota instead of in Agaricus, though all 
the other generic characters are identical. 
A few specific points might be described more in de- 
tail. The pileus is usually quite sm.oothj though in some 
specimens the surface shows numerous very fine cracks, 
which give it a granular appearance. The pileus is usu- 
ally very symmetrical, rounded when young and strong- 
ly convex when mature. The flesh is soft and white, but 
remains much firmer in age, and when picked, than does 
that of Agaricus campestris. 
The veil is also firmer than in the case of Agaricus 
campestris. It separates cleanly from the margin of the 
pileus, as well as from the stem, so that it forms a per- 
*Subgenus according to some. 
