MUELLER: OBSERVATIONS OS LAMIVARIA BULLATA KJELLM. 307 



as long cylindrical tubes — with the inner side crenate and the 

 outer straight, and with the secreting cells very granular {fig. 7). 



The cortex cells of the stipe are not so large as those of the 

 haptere (fig's. 10, 11). The strengthening cells found near the 

 pith web, are in general cylindrical in form ; the innermost are 

 imbedded in mucilage. These cells are characterized by each 

 possessing an unusually large nucleus. The granular proto- 

 plasm passes through the center of the cell and communicates 

 with that of adjoining cells through the end partition walls. 



The pith web is formed of interlacing, colorless hyphae. In both 

 cross and longitudinal sections can be seen some hyphae which 

 have been cut obliquely and others which have not been cut at 

 all, showing that they run in various directions. The majority 

 of them take a lengthwise course, however. The hyphae (fig's. 

 12, ij) have comparatively thick walls, are imbedded in mucilage 

 and contain protoplasm and some starch grains. Trumpet 

 hyphae are numerous and are found running lengthwise more 

 often than crosswise. 



In the lamina we see again the same tissues as in the stipe. 

 The chromoplasts of epidermal and hypodermal cells are more 

 numerous than in the corresponding cells of the stipe. The 

 mucilage ducts are not so numerous nor so compressed, being 

 circular rather than elliptical in outline (fig. 14). The cells of 

 the cortex are large and cuboidal in form (fig. J 4) and follow- 

 ing these are the thick-walled strengthening cells, circular or 

 oval in cross section (fig. 15), and often arranged in pairs as 

 though recently divided ; elongated and of uniform diameter in 

 longitudinal section (fig. 16). In these cells the hyphae of the 

 pith web take their origin, as branches from the sides of the 

 cells, or as a prolongation of the cell proper (figs. 15, 16)'. 



In some cases the hyphae can be traced from their origin in 

 one cell, across the pith web to their termination in another cell 

 on the other side. The pith web is richly supplied with mucilage, 

 and imbedded in this are numerous trumpet hyphae — which do 

 not differ from those of the stipe (fig. 17)- 



The bullations, which are so striking a feature of the plant, 

 are not due to a thickening of any of the tissues of the lamina, 

 but rather to a bending in and out of these tissues, the epi- 

 dermis, cortex and pith web following each other in the same 

 order and proportion as they do in the even portions of the 

 lamina. 



