THE FUNGI 



261 



hym 



(d) The structure of the gills, as shown in a mushroom split 

 lengthwise through the stem and cap and examined with the mag- 

 nifying glass. 



Cut ofE the stalk of a well-expanded mushroom or toadstool close 

 to the cap and place the latter, giUs down, on a sheet of paper. If 

 the gills are light-colored use black paper, if dark- 

 colored, white paper. After some hours lift off 

 the cap and examine the print left by the spores. 



(e) The extent of the mycelium as far as it 

 can be traced in the earth or other substratum 

 on which mushrooms or toad- 

 stools are growing. 



338. Minute Structure of the 

 Gills. — Cut thin sections of 

 one of the gills at right angles 

 to its flat surface. Mount and 

 examine first with m.p. and 

 then ^Yith h.p. If spores are 

 not shown, as in Fig. 187, re- 

 peat with part of a gill from 

 another mushroom. Xote : 



(a) The general structure 

 of the gill, the interior consist- 

 ing of loosely interwoven hy- 

 phse and the external fruiting 

 portion, the hymenmm, consist- 

 ing of ends of hyphse definitely 

 arranged. ^Vhat is their position relative to the surface of the gill ? 



(V) The basidia, or club-shaped tips of spore-bearing hyphse. 



(c) The sterigmata, or short stalks on the basidia, each sterigma 

 bearing a spore. 



(c?) The size, shape, and color of the spores and the number borne 

 by each basidium. 



(e) The sterile filaments parallel to the basidia and lying between 

 them. 



339. Discussion. — The gill fungi (including most of the 

 toadstools and mushrooms) are some of them saprophytic 



Fig. 186. Portions of Gills of a 

 Fungus (Agarlcus). 



A, slightly magnified. B, one of the parts 

 of A, more magnified ; hym, hymenium ; 

 h, centra} layer. 



