20S2 



MI'SHROOM 



MUSHROOM 



2406. Agahcus campestris ^the true 

 mushroom). ( X ! ^) 



of Munich. "Tomlstool" is u toiin wliich mifiht well 

 tn' heUl snoivii to tin- f;\iry talos of luushiooiu lilV. 



It sjHMiis probiiblo tluit mushroom is di'iivoil from 

 the old Fn'iu'h mousi>ron or nioui-hcroii, lunv mousscron. 

 An obsoloto Knsilisli fijrm is muslu'ron, while imish- 



nimii ami miish- 

 romc have also l)Opn 

 used. Anion}; con- 

 sumers of iMx-nch 

 canned 'VhampiR- 

 nons" (fungi) there 

 seems to be the 

 feeling that this 

 general term is used 

 only for the eulti- 

 vatcd forms, but 

 this is merely a 

 special trade use, 

 and even in poijular 

 mushroom books 

 the cultivated 

 forms aix! carefully 

 distinguished !is 

 "champignon de 

 couche." 



The only muslirooras cultivated extensively in Europe 

 or America are the "common mushrooms," or field 

 mushrooms, consisting probably of several closely 

 related species, which are usually designated Agaricus 

 campfstris. In reality, there is a group of species, 

 including at least .4. arvensis, A. campcstris and its 

 near relatives, .4. irillaticus, probably .4. Rodmani and 

 .4. fahaceus, any of which may be cultivated. It is 

 not too much to hope that in time representatives 

 of several other genera of the fleshy fungi may be cul- 

 tivated for special purposes, but it is doubtful whether 

 any species in culture would yield more abundantly 

 than do the forms now grown. These species closely 

 resemble one another in general rliaracteristics and in 

 life historj', so that a description of a common type of 

 ..4. campeslris will define all with sufficient accuracy for 

 the present purpose, and it will indicate in general the 

 terminology of all the Ba.sidiomycetes, that is, the class 

 of fungi which contains the larger part of the fleshy 

 forms. 



Characierislics of Agaricus campeslris (Fig. 2406). 



The full-grown expanded plant is somewhat 

 umbrella-like, with a central stalk (stipe) supporting a 

 rather thick cap (i)ilcus). The st<"m may be from 

 2 to .5 inches in height, about 1 inch in diameter, and 

 above the middle there is typically a ring or annulus, 

 but there are no other appendages about the stem. The 

 cap bears on the under surface tlie gills, blade-like 

 lamellzE reaching for the most i)art from near the 

 stem to the periphery of the cap. When the ca]! of the 

 young mushroom begins rapidly to expand, it breaks 

 away from its attachment to the stem, and the veil of 

 tissue which has hidden the gills from view is ruptured 

 at the periphery of the cap, leaving the ring or annulus 

 already mentioned. W'hen the gills are first disclosed 

 they are of a beautiful pink color, but with age they 

 darken and ultimately becomi' brown-black. 



The coloration of the gills referred to is due chiefly 

 to the formation of spores or i)roi)agativ(^ {'ells, in large 

 number. If one places the cap of a maturing mush- 

 room on a piece of white paper, gills downward, pro- 

 tecting the cap from rapid drj'ing out, a perfect spore 

 print of the brown-blaf;k spor(^s may be mafje. The 

 number of these produced by a single mushroom 

 expressed in figures is too great to be adequately 

 pa.'sped. The spores arc small ovoidal cells, as shown in 

 Fig. 2407, and they are borne upon club-shaped struc- 

 turr^ termcfl basidia, — these being organs which are 

 characteristic of the whf)le cl.a,s,s of the IJasidiomycetes. 

 The entire surface of the parallel gills is studded with 



the ba.sidia, each basidium bearing from two to four 

 spores. 



Vcgctalive and. fruiting stages. 



In the ojien the spores doiibtless germinate, but the 

 conditions for llieir germination are not .so well under- 

 stooil that they can be readily duphc.ated in the labora- 

 tory. .\t any rate, germiitation of the spores j'ields a 

 mycelimn or thread-like growth that is characteristic of 

 most fungi. The development and growth of the 

 m.yceliinn in rich earth, comjiost, or manure yields a 

 characteristic, "spawm," for ".spawn" is merely the 

 abundant develoimient of the mycelium, or vegetative 

 .stage of the fimgiis, in any stiitahlc substratum. In 

 this connection it is well to note that the mycelimn of 

 other fungi may invade a great variety of substrata. 

 Kich earth, the moist leaves of the forest floor, fallen 

 timber, and even the trunks of living trees are all 

 invaded by a variety of sjiecies, each having its par- 

 ticular growth-requirements. I'Vesh spawn of Agaricus 

 campf>:tris has a fine aroma of muslu"ooms combined 

 with that of almonds. By this aroma alone it may be 

 easily recognized, and therefore <lisfinguishcd from the 

 mycelium of common mould fungi. Hy pure-culture 

 methods, musliroom spawn may also be develoijcd 

 from fragments of the tissue, a-s subsequently indicated. 

 Spawn is appropriately called the vegetative stage 

 of the fungus. 



The mycelium not only- absorbs from the substratum 

 the necessary water, together with the organic and 

 inorganic food materials ncccssiu'y for its immediate 

 growth, but obviously there is accumulated a con- 

 siderable amount above the growth needs, which serves 

 as a fine adjustment to the heavy demands for food 

 made .somewhat later when fruiting begins. With a 

 vigorous development of spawn in earth or compost, 

 fruiting, or muslu-oom formation, will proceed. At this 

 time the tlireads of spawn become more strongly corded 

 and matted, attended by the formation of spherical 

 "pinheads," and the latter develop directly into the 

 well-known "button" stages, the appearance and rapid 

 development of which give such satisfaction to the 

 novice in mushroom-growing. With the increase in 

 size of the button and the dilTerentiation of gills, there 

 is next a rapid exjjansion of the cap and the elongation 

 of the stem, followed by the rujiture of the veil. The 

 mushroom is then full growm, at which time the shed- 

 ding of spores begins. 



Mushroom-culture. 



In times past, it has been the custom to regard mush- 

 room-growing as more or less of a mystery. It was 

 therefore c o n - 

 sidered impos- 

 sible to lay down 

 specific rules for 

 the guidance of 

 others. This was 

 due primarily 

 to the fact that 

 there had been 

 very little e.\- 

 jierimental work 

 from which to 

 deduce tht; prin- 

 ciples on which 

 successful cul- 

 ture dejiends. 

 There is now no 

 reason why an 

 intelligent p<'r- 

 son shoulil not 



be able to pro- 2407. Section of a gill of Agaricus cam- 



duce mushrooms pestris, enlarged; Ir, trama; sh, hymen- 

 successfully if he lum; b, basidium; si, sterigma; sp, spore. 



