28o 
G. R. BISBY 
In longitudinal sections of very young stages, the hollow stalk is 
seen extending as a comparatively large, cylindrical cavity from the 
very base of the fruit body up to near its summit. The plasma mem- 
brane surrounding this central cavity secretes the hollow stalk up 
which the protoplasm climbs to form finally the sporangium along its 
upper portion. Figure i6 shows in median section the upper portion 
of such a central axis, cut somewhat obliquely. At its very apex, 
the irregular and rather tubular space in which the columella is formed 
appears broader than it is below, where deposition of wall substance 
has begun. In the lower part of figure i6 the somewhat shrunken and 
diagonally cut columella has attained some degree of thickness from 
deposition of wall substance from the plasma membrane. Into the 
upper portion of this space may be noted the intrusion of finger-like 
processes of protoplasm, while some irregular masses of protoplasm lie 
detached within the cavity itself. Indeed, one quite commonly notes 
in sections the presence of protoplasmic masses inside the columellar 
cavity, even in much older stages. The figure illustrates quite clearly 
just how their presence in such situations is to be explained, arising 
as they do from fragments detached from above by the ever advancing 
columellar apex. This point will be considered in some detail in the 
general discussion which follows. 
Just above the apex of the cavity in which the stalk is being formed 
is seen the much vacuolated protoplasm which marks the region into 
which the columella is soon to advance. Denser areas lie still further 
beyond; while still other dense areas are shown at the sides of the 
upper portion of the space. Extending upward at a slight angle from 
the rising columellar cavity may be noted a tubular space. Careful 
focusing at this part of the preparation reveals in fact a profusion of 
such narrow spaces, radiating in an upward direction from the apex 
of the large cavity and extending in some cases even to the periphery 
of the mass of protoplasm. Occasionally it can be seen that such tubu- 
lar spaces are directly connected with the main large columellar 
cavity, the plasma membrane of the one being continuous with that 
of the other. 
Forming capillitial threads may be noted in quite an early stage 
of the sporangium. Not, however, until the structure had assumed its 
final form, in the fruiting material studied, were the capillitial threads 
observed in any abundance. The method of deposit of capillitium 
in Stemonitis fusca appears to be in entire agreement with the process 
