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 XL, 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 till the repro- 

 ductive organs form. Sfireds and layers of this mucilage may 

 also be found outside the conceptacle around its mouth. Fre- 

 quently it closes the neck of the conceptacle 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 in the 

 wall of the conceptacle grow and multiply the arch which they 

 form would create a distinct pressure on the surrounding tissue. 



