36 : MINNESOTA BOTANICAL STUDIES. 
neck is formed to the cavity, this neck being composed of epi- 
dermis-like cells. ‘The original cortical rows are at first slightly 
deflected around the forming cavity, but later become deeply 
invaginated and thus aid in the deepening of the conceptacle. 
The cells of these layers become flattened and lenticular in 
shape, and are arranged in concentric layers, three to five deep, 
around the cavity thus forming a basket-like receptacle. The 
cells on the side toward the cavity are thin-walled and small, 
the outer cells are larger and have more intercellular jelly 
(Pl. XI., Figs. 27-29). 
The cavity of the conceptacle is generally nearly spherical. 
Occasionally it is oval in shape with the longer axis in various 
directions. Where several conceptacles occur close together, 
there may be considerable distortion in their shapes. 
The cortex over the conceptacle is slightly elevated by the 
growth of the conceptacle, but is gently curved again into the 
ostiole. The angle between the epidermis and the conceptacle 
is filled in with rather irregularly disposed cortex cells belonging 
to the deeper strata. The pith is sharply marked off from the 
flattened cortical cells around the conceptacles. 
The mucilaginous remains of the disintegrated cells stay 
within the cavity for a considerable time, even tiil the repro- 
ductive organs form. Shreds and layers of this mucilage may 
also be found outside the conceptacle around its mouth. Fre- 
quently it closes the neck of the conceptacie like a stopper 
(fig. 27). It seems to be finally partly absorbed and partly 
extruded by the paraphyses. 
Bower thinks that the protrusion of the conceptacle into the 
pith is caused by the turgidity of the conceptable when filled 
and stoppered with the mucilaginous contents, the bulging being 
rather toward the softer and more yielding pith than toward the 
more rigid cortex, though even here it is noticeable. This 
explanation is insufficient, as it hardly seems possible that the 
conceptacle is closed tightly enough for the purpose, and 
especially since the greatest swelling of the conceptacle into 
the pith is in the later stages when the cavity has already begun 
to discharge or absorb the jelly and is no longer completely 
filled nor tightly closed. The principle of the arch might help 
to explain this protrusion of the conceptacle. As the cells inthe 
wall of the conceptacle grow and multiply the arch which they 
form would create a distinct pressure on the surrounding tissue. 
