324 PRACTICAL COURSE IN BOTANY 
under the microscope and notice that it is 
composed of delicate filaments made up of 
single cells placed end to end, as in Spi- 
rogyra (341). These filaments are called 
hyphe. 
370. The button. — Look on the my- 
celium for one of the small round bodies 
called buttons (Fig. 457). These are the 
beginning of the fruiting body popularly 
known as the mushroom, and are of va- 
rious sizes, some of the youngest being 
Tic. 457. — Mycelium iss 
ofamushroom (Agaricus barely visible to the naked eye. After a 
campestris), with young ,- : 
buttons (fruiting organs) time they begin to elongate and make 
z a penta marr their way out of the substratum. 
fication at successivepe- 371. The veil and the volva.— Make a 
Tiods of development; vertical section through the center of onc 
mycelium ; st, stipe; p, 
pileus; J, gill, or lamina; of the larger buttons after it is well above 
Ee ground, and sketch. Notice whether it is 
entirely enveloped from root to cap in a covering membrane 
—the volva (Fig. 458, a) — or 
whether the enveloping mem- 
brane extends only from the | 
upper part of the stem to the 
margin of the cap — the vevl (Fig. 
458, d); whether it has both veil 
and volva, or finally, whether it 
is naked, that is, devoid of both. 
372. The stipe, or stalk.— 
Notice this as to length, thick- 
ness, color, and position; that is, 
whether it is inserted in the 
center of the cap or to one side 
(excentric), or on one edge (lat- 
eral). Observe the base, whether — yg. 458, — Diagram of unex- 
bulbous, tapering, or straight, panded Amanita, showing parts: ua, 
volva; b, pileus; c, gills; d, veil; e, 
and whether surrounded by 4@ stipe; m, mycelium. 
