CHARACTERS OF MUSHROOMS. 



303 



mere veins or ridges. Again, the edge is generally entire, i. e., not 



noticeably toothed, but in Lentinus it is often toothed or cut in various 



ways. In some other 



plants the edges are 



serrulate, crenulate, 



etc. In Schi:{ophyl- 



lum alneum, a small 



whitish plant very 



common on dead 



sticks, the gills are 



split lengthwise 



along the edge with 



the halves revolute, 



i. e., rolled back. In 



Coprinus the gills 



and often a large 



part of the pileus 



melt at maturity into 



a dark, inky fluid. 

 The hymenium. 



The term hymenium 



is applied to the 



spore-bearing tissue 



of many fungi. In the Agaricacece the hymenium covers the entire 



surface of the gills and usually the portion of the pileus between 



the gills. It originates 

 in the following man- 

 ner : the threads form- 

 ing the trama of the 

 gills grow out from the 

 lower side of the pileus 

 and perpendicular to its 

 under surface. As 

 growth advances many 

 branches of the threads 

 turn outward toward 

 either surface of the gill 

 and finally terminate 

 ^ ,^1, XT, , T7 . in club-shaped cells. 



Figure 250. Inocybe repanda (Bull.) Bres. (= Ento- n i_ r 



loma repandum Bull.), t, trama of pileus; sh, sub- These cells, therefore, 



hymenium; h, the hymenial layer; the long cells jjg side bv side perpen- 

 with a drop of moisture at the ends are cystidia ^ ' F r 



(sing, cystidium). dicular to the surface, 



Figure 249. Section of portion of gill of Marasmius 

 cohaerens. t, trama of gill ; sh, subhymenium ; h, 

 hymenium layer. The long, dark cells are brown 

 cystidia, termed spicules by some to distinguish them 

 from the colorless cystidia. The long cells bearing 

 the oval spores are the basidia. 



