73 



74 



the cap, botanically known as the pileous. 

 This is generally supported on a stem, but 

 in the absence of a stem the cap is ses- 

 sile. It varies much in shape in differ- 

 ent species and even in the same species 

 in different stages of development. In 

 some mushrooms, thin vertical plates or 

 membranes radiate from the stem to the 

 margin of the cap, or in the absence of a 

 stem, from the point of attachment of 

 the cap to its free margin. These are 

 called lamellae or gills. Shorter ones in- 

 tervene toward the margin of the cap to 

 fill the spaces that would otherwise be 

 left vacant. The gills are attached by 

 their upper edge to the lower surface of 

 the cap and often by their inner extrem- 

 ity to the stem. They are adnate when 

 attached to the stem by the whole width 

 of their inner extremity; adnexed when 

 attached a part of their width only; de- 

 current when they run down on the stem, 

 gradually tapering to a point, and free 

 when not attached to the stem. Some- 

 times their lower edge is notched or ex- 

 cavated at or near the stem, which fact 

 is designated by the words emarginate or 

 sinuate. 



In some, the lower surface of the cap 

 is full of small holes or cells, called 

 pores. These are so small in some spe- 

 cies that they are scarcely noticeable, but 

 generally they are easily visible. They 

 stand like tubes in a vertical position, side 

 by side, with the openings or mouths 

 downward. Theoretically they may be 

 supposed to be formed by numerous gills 

 connected by frequent partitions or trans- 

 verse membranes. 



In still another group of mushrooms the 

 lower surface of the cap has neither gills 

 nor pores, but instead there are numer- 

 ous spine-like or awl-shaped projecting 

 points called teeth. It is very much as if 

 closely placed gills had been deeply, regu- 

 larly and finely notched or gashed, but 

 the teeth are not arranged in regular rad- 

 iating rows, as they would be if actually 

 formed in this way. 



The upper surface of the cap is glabrous 

 when it is smooth or free from hairs, 

 fibrils or scales; even when it has no pits, 

 ridges or other inequalities; silky when 

 adorned with soft, close-pressed fibrils; 

 fibrillose if these fibrils are harsher and 

 lower; flocose when they are soft, short 

 and collected in little floes or tufts; to- 

 mentose when crisped and interwoven so 

 as to form a woolly surface; squamose or 

 scaly when coarse and collected in tufts, 

 also when the cuticle breaks or cracks 

 into small flakes or spot-like patches. 

 These same terms are also applicable un- 

 der the same conditions to the surface of 

 the stem. The cap is also said to be um- 

 bonate when it has a small projection or 

 boss on its center; umbilicate if it has a 

 small central cavity or umbilicus, and 

 hygrophanous when it has a soaked or 

 watery appearance, the loss of which by 

 drying is accompanied by some change in 

 color. The margin of the cap is stricate 

 when marked by nearly parallel radiat- 

 ing lines. If these lines are very slight 



or are visible only in the moist or hygro- 

 phanous state, the fact is indicated by 

 the term sticatulate. 



The stem is equal or cylindrical when it 

 is of uniform diameter in all its length; 

 bulbous when more or less abruptly en- 

 larged at its base; stuffed when its inter- 

 ior or ventral part is of a softer or looser 

 texture than the exterior. In some mush- 

 rooms a thin membrane, in others a mass 

 of webby filaments, stretches from the 

 stem of the margin of the cap and con- 

 ceals the gills in the young plant, but as 

 the cap expands, this membrane, called 

 the veil, usually separates from the mar- 

 gin of the cap and adheres to the stem, 

 forming around it a ring or collar, botani- 

 cally known as an annulus. 



In a few species the young plant is 

 wholly enveloped in a membranous or 

 somewhat tomentose volva or wrapper, 

 but this is soon ruptured by the growing 

 plant and its remains arein some cases 

 entirely left at the base of the stem, in 

 others they partly adhere to he upper sur- 

 face of the cap in the farm of warts, or 

 more rarely and exceptionally in a few 

 small irregular patches. The dangerously 

 poisonous species occur in a genus in 

 which the volva is a prominent character. 



The spores are the seeds or reproductive 

 bodies of mushrooms. They are as fine 

 as dust and are invisible to the naked eye 

 except when collected together in great 

 numbers or in masses. The hymenium is 

 the surface or part of the plant immedi- 

 ately concerned in the production of the 

 spores, and the hymenophore or hymeno- 

 phorum is the part that supports the hy- 

 menium. In the Common mushroom and 

 many others as well, the spores develop 

 on certain specialized cells called basidia 

 (basidium in the singular), on each of 

 which four spores usually develop. In the 

 morels, these specialzed cells are elon- 

 gated into cylindrical membranous sacks 

 called asci (ascus in the singular), in each 

 of which eight spores usually develop. In 

 germination the spores send out slender 

 threads cv filaments called mycelium by 

 botanists, but commonly known as spawn. 

 The mycelium permeates the soil or other 

 substance on which the mushroom grows 

 and under favorable circumstances devel- 

 ops a crop of mushrooms of its own spe- 

 cies. 



Agaricus campester L. 



A: campestris is the form in which this 

 name is commonly written, 'but in Sylloge 

 Fungorum the more classical and gram- 

 matical term here adopted is used." 

 (Peck.) 



Pileus silky or squamulose; gills at 

 first delicate pink, becoming brown or 

 blackish-brown with age: st stuffed, glab, 

 w or w'ish; spores elliptical, 0.00025-0.0003' 

 lg, sometimes described as purplish-brown, 

 but Peck says he has never been able to 

 see any decided purple tint in them, but 

 aoproaching seal brown through not as 

 dark. Cap 3-4', st 1-3' lg. 



A cosmopolitan species, the com mush- 

 room, called the meadow mushroom be- 



