p s t e I s i a 273 



Figure 10. Specimen with orbicular sorus 

 at base of lamina. 



Figure 11. Large plant measuring 23x6 

 centimeters which has not yet begun to develop 

 a sorus. 



Figure 12. Plant with five longitudinal 

 stripes of fertile tissue. 



Figure 13. A very long narrow plant 3 

 X 118 centimeters. 



Plate XVIL Photomicrographs of the stipe- 



1. Radial view of portion of cross section 

 showing the tissues from the pith outward. B. 



& L. obj. f, oc. I. 



2. Portion of above showing in detail the 

 pithweb and the innermost portion of the 

 cortex. B. & L. obj. ^, oc. 2. 



Plate XVIII. 



1. Longitudinal section of the stipe showing 

 the pith-web with elongated cells of the inner 

 layers of the cortex. B. & L. obj. ^, oc. 2. 



2. Radial section of a holdfast showing an 

 appressed secondary branch. Leitz obj. i, B. 



& L. oc. 2. 



