Development of Ephelis . 37 
bundles (Fig. 3). The stroma consists of a compact, colour- 
less, uniform, pseudo-parenchymatous tissue, surrounded by 
a blackish rind or cortex. The hyphae of the central portion 
are frequently branched, aseptate, or with only an occasional 
septum, thick-walled, and with small lumina, and as they 
pass to the outside to form the cortex become thin-walled, 
dark-coloured, and furnished with numerous septa. The 
greater part of the surface of the cortex is smooth, but here 
and there some of the dark cortical cells continue to elongate 
beyond the general surface, and form velvety patches (Fig. 3, 
c). It is remarkable how comparatively few hyphae are to be 
met with in the tissues of the main axis or branches of the 
host, there being no displacement of cells or general disin- 
tegration of the cell-walls ; even the hairs on the surface 
remaining intact (Figs. 4, d and 5, d). The hyphae pierce 
the walls of the cells, and sometimes give off short, inflated 
branches, which probably act as organs of absorption (Fig. 4, 
c). The earliest external evidence of the Ephelis or gonidial 
stage of reproduction is indicated by the presence of numerous 
minute elevations scattered somewhat uniformly at short dis- 
tances over the hitherto even surface of the stroma. A vertical 
section through one of the pustules at this stage shows the 
hyphae of the colourless portion of the stroma immediately 
below the cortex to be arranged more or less parallel and 
vertical to the surface for a depth of 20-30 /x. This mass 
of differentiated hyphae, which is biconvex in vertical section, 
continues to increase in size on the side next the cortex until 
the latter is eventually ruptured, forming an elliptical or 
irregularly circular opening from 1-2 mm. across. The 
margin of the ruptured cortex is raised in the form of a 
border surrounding the central exposed portion, and presents 
under a low power a fringed appearance, due to the com- 
ponent hyphae of the cortex becoming separated by the 
pressure from below, and standing erect round the torn 
margin (Figs. 5 and 8). The parallel hyphae forming the 
disc of the cavity consist at first of aseptate branched fila- 
ments, the apices of which are eventually abscised as con- 
