MacMillan: OBSERVATIONS ON PTERYGOPHORA. 741 



4. Tangential section through secondary cortex, showing the some- 

 what fusiform outline of the cells in this section (x 50). 



5. Longitudinal section through region of Fig. 3. On the left is 

 seen the tissue of the secondary cortex, in the middle the flattened 

 cells of the transition zone, and on the right the cells of the primary 

 cortex. This first ring of growth, caused by the superposition of 

 secondary upon primary tissue, is the most prominent of all the 

 growth rings in the stipe ( X 50). 



6. A portion of the secondary cortex tissue shown in Fig. 5, mag- 

 nified to demonstrate the pits in the vertical walls of the tracheid- 

 likc elements. To the right the cells become compressed, passing 

 into the transition zone ( X 250). 



7. A portion of the primary cortex tissue shown in Fig. 5, mag- 

 nified to demonstrate the different arrangement of primary and 

 secondary cortical cells. The secondary stand in long rows at the 

 same level. This is not true of the primary ( X 250). 



8. Cross section through one of the rings shown in Fig. i and 

 magnified to demonstrate the flattening of cells in the region of the 

 ring and their denser contents. The appearance of small cells inter- 

 polated between the larger ones can be understood by referring to Fig. 

 4 (X 250). 



9. Cross section through pith web of stipe, showing anastomosing 

 filaments and trumpet hyphaB embedded in a gelatinous matrix (x 

 250). 



10. Cross section through haptere. The cells of the outer cortical 

 region are crowded with contents, and do not differentiate clearly. 

 Near the middle of the section are seen two of the characteristic 

 growth-rings of the haptere (x 50). 



1 1. Longitudinal section through haptere, showing the development 

 of secondary tissues, the cells of which are shorter upon the primary 

 tissue towards the bottom of the figure. Below the black outer cortex 

 a growth-ring in section may be seen ( x 60). 



12. Section through sorus, showing floor-cells, gonidangia with 

 gonidia and paraphyses capped with cuticular knobs characteristic of 

 this genus and of Lessonia ( x 320). 



All the figures in Plate LXII. are from original photomicrographs 

 by Mr. H. L. Lyon. 



