MUSHROOMS, EDIBLE AND OTHERWISE 



The substance of all mushrooms is either fleshy, membranaceous, or cork v. 

 The pileus or cap is the expanded part, which may be either sessile or supported 

 by a stem. The pileus is not made up of cellular tissue as in flowering plants, 

 but of myriads of interwoven threads or hyphae. This structure of the pileus 

 will become evident at once if a thin portion of the cap is placed under the 

 microscope. 



The gills or lamella are thin plates or membranes radiating from the stem to 

 the margin of the cap. When they are attached squarely and firmly to the stem 

 they are said to be adnate. If they are attached only by a part of the width of 

 the gills, they are adnexcd. Should they extend down on the stem, they are 

 decurrent. They are free when they are not attached to the stem. Frequently 

 the lower edge is notched at, or near, the stem and in this case they are said to 

 be emarginate or sinuate. 



Figure 2 Small portion of a section through the spore-bearing layer of a 

 mushroom which produces its spores on the ends of cells called basidium. 

 (a) Spores, (b) basidium, (c) sterile cells. 



In some genera the lower surface of the cap is full of pores instead of gills ; 

 in other genera the lower surface is crowded with teeth; in still others the sur- 

 face is smooth, as in the Stereums. The gills, pores and teeth afford a founda- 

 tion for the hymenium or fruit-bearing surface. It will be readily seen that the 

 gills, pores and teeth simply expose in a very economical way the greatest possi- 

 ble spore-bearing surface. 



If a section of the gills be examined by a microscope, it will be observed 

 that upon both sides of the surface are extended hymenial layers. The hymenium 



