32 S etc hell.- — An Examination of the Species 
distortions are less. On cutting across a distortion, the sori 
become visible to the naked eye as small brown particles, 
present in such numbers as to give the cross-section a mealy 
appearance. 
The sori are globular light-brown bodies, from too fx to 
140 [jl in diameter. In structure they resemble those of the 
form described as the type of D. occulta so nearly that it 
is hard to find any satisfactory difference (cf. Figs. 79 and 81). 
The sori, on the average, are slightly smaller than those of 
D. occulta ; the spores are a trifle smaller (8 /x to 10 /x by 4 /x to 
8/x) ; and the cells of the cortex rather larger in proportion to the 
spores (being 8 /x to 1 2 j u, tangentially and 4 [i to 6 jx radially). 
But the germination is entirely different from that of D. 
occulta. The spores are a fixed part of the sorus, as in 
D. occulta , and germinate in position. So we have the sori 
surrounded by a dense covering of promycelia and sporidia, 
bristling with them like a chestnut-bur with its spines. The 
promycelium is obconical in shape, and reaches a length of 
about 12 /x. At the distal end it is 6 /x in diameter and at the 
proximal end only 4 /x. 
In D. occulta also the promycelium is somewhat broader 
at the tip, and it may be a characteristic of this section 
of the genus. The sporidia are usually 5 or 6 in number, 
and are inserted in a whorl on the blunt tip of the promy- 
celium (Figs. 51 to 53). They are about 12/x long and 4 to 
5 /x thick. They are thickest at the middle and taper to 
both ends when mature (Fig. 52). At maturity they conjugate 
in pairs, either at the base (Fig. 57) or at the apex (Fig. 58). 
The conjugated pairs germinate by means of a germ-tube. 
Soon after leaving the sporidium, the germ-tube increases in 
diameter (Figs. 54 to 57 )- It is soon constricted again, and 
so on at regular intervals (Fig. 55). This gives the germ-tube 
a curious appearance, as if it were going to break up into 
secondary sporidia. They reach a length of about 150 /x or 
160 [x in water-cultures and then die. 
The odd sporidium soon drops from the tip of the promyce- 
lium and apparently dies. The sporidia which have conjugated 
