24 Setchell. — An Examination of the Species 
infested by the fungus, the sclerotic character of the testaceous 
nutlet of the ripened fruit. The epicarp retains its normal 
character, but soon macerates away, as it does also in the 
ripened fruit. 
The sori are nearly globose or slightly ellipsoidal, but often 
very irregular, and vary from I20jix to 140 /x by 100 /x to 
1 do fji. They are of a light-brown colour. They are very 
firmly constructed and can be crushed with difficulty. When 
crushed they do not separate into spores, but show peculiari- 
ties of structure which can be understood only by the study 
of thin sections. 
The central part of the sorus is found to be made up of 
a mass of large polygonal cells which have the appearance of 
parenchymatous tissue (Fig. 79). They appear to be destitute 
of solid contents. About this mass of parenchymatoid tissue 
there is a single layer of spores, and outside of this a well- 
developed cortex. The spores are about 12 /x by 10 /x, some- 
times slightly elongated radially, with thin walls, granular 
contents, and closely connected with the layers on either side 
of them. The cortical cells are polygonal in tangential section 
and decidedly flattened radially, measuring in cross-section 8 /x 
to 10/x in the tangential direction and only 1*5 /x to 3 /x in the 
radial direction. Outside the cortex is a thin layer of hyphae 
( F; g- 79 )- 
The development of the sori presents several deviations 
from the course of development either of D. alismatis or of 
D. obscura. The hyphae collect into a loose ball as in those 
species, but soon the inner hyphae, which are more closely 
compacted in this species, appear to radiate in all directions 
from the centre, and are surrounded by a thick coat of con- 
centric hyphae. Fig. 80 represents this stage in D. Marti - 
anoffianai a nearly related species. The radiating structure 
becomes more and more indistinct as the cells begin to appear 
in the interior of the forming sorus, until finally the central 
portion assumes the characteristics of parenchyma, and there 
are formed, just beneath the outer coat of hyphae, more or less 
radially elongated cells, filled with a highly refractive, gra- 
