326 



PRACTICAL COURSE IN BOTANY 



463 



375- The hymenium. Cut a tangential section through 

 one side of the pileus and sketch the section of the gills as 



they appear under a lens, or a low 

 power of the microscope. Notice 

 , s that the blade consists of a central 

 p portion called the trama (tr, Fig. 462) 

 p and a somewhat thickened portion, 

 h, constituting the hymenium, or 

 spore-bearing surface. Now exam- 

 ine, under a high power, a small sec- 

 tion from the edge of a gill, including 

 a bit of the trama. Notice that this 

 last consists of a tissue of mycelial 

 cells (Fig. 463) covered by the hy- 

 menium, or spore-bearing membrane, 

 which is thickly clothed with a layer 

 of elongated, club-shaped cells (b, b 

 and p, p, Fig. 463) set upon it at right 



Some of these 



461 



462 



FIGS. 461-463. Section of a 



gilled mushroom : 461, through angles to the 

 oneside showing sections of the t Qut from twQ to f Qr j n g 



pendent gills, g, g (slightly mag- J 7 1 



species as many as eight, little 

 prongs, each bearing a spore (s, s, Fig. 



nified) ; 462, one of the gills 



the broad border formed by the 

 hymenium, h 463, a small sec- 

 tion of one side of a gill very 

 much enlarged, showing the 

 club-shaped basidia, b, b, stand- 

 ing at right angles to the surface, 

 bearing each two small branches 

 with a spore, s, s, at the end. 

 The sterile paraphyses, p, are 

 seen mixed with the basidia. 



463), while others re- 

 main sterile. The spore- 

 bearing cells are called 

 basidia; the steri e 

 ones, paraphyses; and 

 the whole spore-bearing surface together, the hymenium, from 

 a Greek word meaning a membrane. It is from the presence 



464 



465 



FIGS. 464, 465. A tube fungus (Boletus edulis) : 

 464, entire ; 465, section, showing position of the 

 tubes. 



