Fig, 



PLATE XXIII. 



Koeberlinia spinosa. 



. 1. S, stone cells filling up lower stomatal chamber; Ph, remains of 

 Phycomycete in outer aperture; d, portion of "dome." Cross section, 

 X 283. 



Fig. 2, Surface view of outer stomatal aperture and epidermal cells. 

 SA, stomatal aperture; EC, epidermal cells. Tangential section, 

 X 283. Compare with fig. 3, plate XXII. 



Fig. 3. View toward outer stomatal aperture from within, showing 

 tips of cells making the "dome." Tangential section, x 283. 



Fig. 4. Section across mid-chamber. Tangential, x 283. 



Fig. 5. View looking toward stoma, showing shelf, s, made by projecting 

 walls. Tangential, X 283. 



Fig. 6. Stoma proper, showing guard cells. Tangential, x 283. Com- 

 pare with fig. 6, plate XXII. 



Fig. 7. Stoma proper, invaded by growth of Phycomycete, Ph. Tan- 

 gential section. 



Fig. 8. Water-storage cells, W, in flower branch, and aerating space, A. 

 Cross, X 283. 



Fig. 9. Portion of older stem, showing empty cells, W, probably for water 

 storage. Cross, x 283. 



Fig. 10. Water-storage cells, W, and aerating space. A, in flower 

 branch. Cross, X 283. 



Fig. 11. Aerating space, A, in spongy parenchyma. Longi-section, X 



