PLATE XXI. 



Koeberlinia spinosa. 



Fig. 1. Five rows of phloem parenchyma cells p. p., as seen in cross 

 section; m, medullary-ray cells, x 283. 



Fig. 2. Sketch of portion of phloem, Ph, region bordering stone cells, S, 

 showing various sizes of cells. Longi-section, x 283. 



Fig. 3. Portion of (2) in detail, sieve tubes, St., and sieve plates, S, and 

 parenchyma cells alongside, p. Longi-section, x 400. 



Fig. 4. Stone cells bordering spongy parenchyma, showing some cells 

 unlignified, and some but partly lignified, parenchyma cells; s, .stone 

 cells; pc, partly lignified; P, unlignified. Cross .section, x 283. 



Figs. 5, 6. Different sizes and shapes of stone cells. Longi-section, 

 X 283. 



Fig. 7. (a) Tapering bast fiber, (b) Portion of long bast fiber, showing 

 tapering part and projections of wall to support neighboring cells, 

 (c) Projections with adjoining cellulose walls in detail, (d) Pits in 

 long fiber. All x 283. 



Figs. 8, 9, lOo, x 55, 283, 636, respectively. Short bast fibers as they 

 occur securely fastened together. 106, sketch showing pits in short 

 bast fiber, x 636. 



