324 



PRACTICAL COURSE IN BOTANY 



Fig. 457. — Mycelium 

 of a mushroom (Agaricus 

 campestris), with young 

 buttons (fruiting organs) 

 in different stages : 1, 2, 

 3, 4, 5, sections of fructi- 

 fication at successive pe- 

 riods of development; m, 

 mycelium ; st, stipe ; p, 

 pileus ; I, gill, or lamina ; 

 V, veil. 



under the microscope and notice that it is 

 composed of deHcate filaments made up of 

 single cells placed end to end, as in Spi- 

 rogyra (341), These filaments are called 

 hyphoe. 



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 

 barely visible to the naked eye. After a 

 time they begin to elongate and make 

 their way out of the substratum. 



371. The veil and the volva. — Make a 

 vertical section through the center of one 

 of the larger buttons after it is well above 

 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 b-, 

 margin of the cap — the veil (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 yi^i. 458. — Diagram of umx- 



bulboUS, tapering, or straight, panded ^mamVa. sho^dng parts: a, 

 111 volva; b, pilcus; c, gills ; d, veil ; e, 



and whether surrounded by a stipe ; m, myceUum. 



