184 MINNESOTA BOTANICAL STUDIES. 



cases, a position in the peripheral end of the cell. Under the 

 microscope they appear finely rose-colored pink with perhaps a 

 purple tinge. They are irregular in outline, apparently in most 

 cases assuming such a shape as will allow them to occupy the 

 peripheral end of the cell to best advantage. The epidermal 

 cells average about 13x5 mic. and the chromatophores about 

 10 x 2 mic. 



Stipe. (Figs. 14-21). A cross section of the stipe shows a 

 similarity in structure to that of the frond. The same areas are 

 present with modifications, however (Fig. 14). The cortical 

 area is composed of cells more elongated than those in the 

 frond and is a larger number of cells deep. Internally these 

 pass into the large cells of the intermediate area (Fig. 19). 

 Here there is a noticeable difference from the condition in the 

 frond. A large number of the elongated central cells find their 

 way into this area and a cross section of the stipe shows them 

 in cross, oblique and even longitudinal section between the 

 large starch-containing cells of the intermediate area which 

 stand out very clearly in large radial filaments (Fig. 21). The 

 central area in the stipe is a very compact area and is made up 

 of a large number of thin filaments interwoven in a very com- 

 plicated manner (Figs. 20, 21). These cells correspond to those 

 of the elongated filament bundles in the frond. There are in 

 the stipe, moreover, a small number of larger cells also elon- 

 gated and corresponding to the cells of similar shape and posi- 

 tion in the frond. In cross section the cut-off ends predominate 

 (Fig. 20), while in longitudinal section the cut-off ends are few ; 

 the longitudinal view of the filaments is the predominant one 

 and the intricate weaving (Fig. 21) is very plainly seen. A 

 longitudinal section through the annulate portion shows the ab- 

 sence of the cortical and intermediate layers in the region of 

 the annulus indicating the continuity of these areas in the frond 

 and stipe (Fig. 15). 



A longitudinal section through the growing point shows but 

 two areas in the growing region. There is no distinct interme- 

 diate area although a number of large cells may be present 

 (Fig. 1 6). The two areas are the cortical in which the fila- 

 ments are all parallel, perpendicular to the stipe surface and 

 pseudc-parenchymatous in character, and the central, which is 

 as before a mass of densely woven elongated filaments. The 

 end of the intermediate area of the frond can readily be seen 

 in such a section (Fig. 16). 



