266 KANSAS UNIVERSITY SCIENCE BULLETIN. 



three cells deep. The cells have a few scattered chloroplasts, 

 and many of them have large clusters of calcium oxalate crys- 

 tals. (Figs. 5, 9, 14.) Beneath this aqueous tissue or paren- 

 chyma of the cortex is a starch sheath. The lumen of the cells 

 averages 0.0525 millimeters tangentially, 0.0175 millimeters 

 radially, and 0.105 millimeters longitudianally. The wails 

 average 0.0058 millimeters thick. 



Beneath the starch sheath is the parenchyma of the peri- 

 cycle, consisting of one row of cells with walls 0.0018 milli- 

 meters thick and the lumen averaging 0.0262 millimeters 

 tangentially, 0.0087 radially, and 0.122 millimeters longi- 

 tudinally. The starch grains in the starch sheath are com- 

 pound. (Figs. 16 and 17.) 



The anomaly of the stem structure gives the cross section 

 of the vascular bundle ring a peculiar appearance. The small 

 mass of phloem cells with their cellulose walls are opposite the 

 tracheal vessels. True spiral tracheal tubes occur in the pri- 

 mary bundle. In the secondary bundles, pitted and spiral 

 tracheids predominate, with some pitted and scalariform 

 tracheal tubes. (Figs. 20 and 21.) 



The phloem consists of undivided mother cells of sieve tubes 

 and companion cells and phloem parenchyma cells. Appar- 

 ently there are no true sieve tubes with their sieve plates. 

 The average phloem cell has walls 0.00147 millimeters thick, 

 with a lumen 0.0088 millimeters radially and tangentially, and 

 0.105 millimeters longitudinally. 



In the phloem a great many of the cells are filled with a food 

 product giving the test for protein, which it probably is. 

 Occurrence of the stuff is common in the phloem of the root. 

 Frequently a cell in the phloem of the stem is filled with cal- 

 cium oxalate crystals cubical in shape. (Fig. 19.) 



Surrounding the tracheal tubes in the primary bundle are 

 xylem parenchyma cells with plain pits. In this bundle the 

 parenchyma cells occupy a considerable space. In the second- 

 ary portion of the vascular bundle only a few xylem paren- 

 chyma cells occur, and these immediately next to the tracheal 

 tissue. Surrounding these cells, and occupying the space be- 

 tween the groups of tracheal tubes, are wood fibers, shown 

 from mascerated sections in figure 15. 



The xylem parenchyma cells in the primary bundle have 

 walls 0.0021 millimeters thick. The lumen is 0.043 millime- 



