102 KANSAS UNIVERSITY SCIENCE BULLETIN. 



occupied by the stone cells is broad. Sometimes the cells are 

 found in the region of the palisade cells, in scattered patches, 

 or in many cases filling up air cavities below the stomatal 

 chamber. (Fig. 1, plate XXIII.) 



The bast appears to be of twofold character — the ordinary 

 long, tapering cells, united by a long splicing, then another 

 kind, shorter and tapering abruptly at one end, while the other 

 end, rather blunt, fits securely into the socket made by the two 

 cells below. (Figs. 8, 9, 10, plate XXI.) These fibers occur in 

 the regular bundles, but they also make a sort of inner bundle, 

 we think ; at least, in all the cases so far examined they appear 

 to occupy that position. They may make a sort of inner sup- 

 porting shaft to the whole group. When separated from the 

 long fibers a bundle of them looks like a barbed shaft. 



The spoyigy parenchyma tissue takes up the inner collen- 

 chyma region. These are about five or six cells deep radially. 

 The walls of some of the parenchyma of the innermost portion 

 are heavily lignified. Neighboring cells have not so changed 

 materially, but the cellulose wall is thicker in many cases. The 

 walls in all the sponge are about twice as thick as those of the 

 palisade region. The spongy cells are spherical, cuboidal or 

 ovoid in shape, and about twice the diameter of the palisade 

 cells. The numerous and large intercellular spaces in this re- 

 gion are conspicuous. There are besides whole rows of open 

 spaces, seen in either cross- or longi-sections. (Fig. 9, plate 

 XXII.) This will be taken up in a later paragraph, however. 



The palisade cells lie in characteristic position, two or three 

 deep radially. They are thin walled, cylindrical in shape, with 

 some, but rather small, intercellular spaces. The chloroplasts 

 are of goodly size, and show a deep blue in treating with c. 

 z. i. In this region also are to be found very large aerating 

 chambers, ovoid in shape, connecting directly with the stomatal 

 chamber above, and thence with the outer world. These are 

 not quite so numerous as the smaller cavities mentioned in the 

 sponge. (Figs. 3, 4, plate XXII.) 



The epidermis is remarkable. The cuticle itself is very 

 heavy, it being 0.015 mm. in thickness in the old stem. The 

 whole epidermis as found in the older stem measures from 

 0.075 mm. to 0.105 mm. There is but one row of epidermis 

 cells. These are elongated radially, and in the younger parts 

 of the plant are of thin cellulose walls. In the older parts the 

 walls become very much thickened, so much so that in time only 



