326 
PRACTICAL COURSE IN BOTANY 
375. The hymenium. — Cut a tangential section through 
one side of the pileus and sketch the section of the gills as 
462 
461 
Fics. 461-463. — Section of a 
gilled mushroom: 461, through 
one side, showing sections of the 
pendent gills, g,g (slightly mag- 
nified) ; 462, one of the gills 
more enlarged, showing the cen- 
tral tissue of the trama, tr, and 
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- 
mainsterile. Thespore- 
bearing cells are called 
basidia; the sterie 
ones, paraphyses; and 
they appear under a lens, or a low 
power of the microscope. Notice 
that the blade consists of a central 
portion called thetrama (tr, Fig. 462) 
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 (6, 6 
and 7, p, Fig. 463) set upon it at right 
angles to the surface. Some of these 
put out from two to four, or in some 
species as many as eight, little 
prongs, each bearing a spore (s,s, Fig. 
464 
465 
Fics. 464, 465. — A tube fungus (Boletus edulis) : 
464, entire; 465, section, showing position of the 
tubes. 
the whole spore-bearing surface together, the hymenium, from 
a Greek word meaning a membrane. It is from the presence 
