38 THE LARCH CANKER 
A section through a ripe apothecium shows the lower 
portion, or excipulum, differentiated into two parts. The 
outer (lower) portion, or cortex (fig. 17, c), is composed of 
a mass of closely interwoven and rather swollen hyphae of 
firm texture. The middle portion is made up of hyphae 
which are much less closely interwoven. The hard cortex 
not only prevents loss of water from the apothecium, but 
also assists in closing it in dry weather. For on drying the 
central portion contracts more than the cortex, and this 
Fie. 17.—Section through apothecium of Dasyscypha calycina: c, 
cortex ; h, hymenial layer; s.J., subhymenial layer. 
causes the margin to fold over the hymenial layer (figs. 
15 and 16). — 
The hymenium (fig. 17, h) is a layer composed of ase? 
and paraphyses, and is borne by a dense subhymenial 
layer, s.l. The details of the hymenial layer are more clearly 
shown in fig. 18, A. The ascus, a, is the organ which pro- 
duces and ejects the spores. The eight spores occur in 
a single row and fill the upper part of the ascus, whilst the 
lower part contains hyaline protoplasm. The length of the 
ascus is 150-200, and the greatest breadth is 10-14. It 
is nearly cylindrical, but somewhat swollen towards the 
upper end, and tapering at the lower end. The walls are 
sufficiently thick to showa double outline under a D objective, 
except at the extreme apex, and are quite smooth. The 
spores (fig. 20, 4) are ellipsoidal, the long axis being 20-23, 
