264 KANSAS UNIVERSITY SCIENCE BULLETIN. 



other cell walls press against their walls. Figure 16 shows 

 some of these cells cut obliquely, showing the great amount of 

 mucilage in some places. In some instances these tubes meas- 

 ure more than one mm. in length. There are also many mu- 

 cilage cells in the collenchyma, but they are not generally larger 

 than the other cells (and therefore too small to show to the 

 scale of figs. 27 and 28) and not many tubes are formed. The 

 pith contains many long tubes filled with mucilage (figs. 15, 27 

 and 28) much the same as those in the parenchyma of the 

 cortex. 



The plant from which this study was begun was brought 

 into the laboratory in June, and was in the second year of its 

 growth. From observations made from this plant it was 

 determined that there is relatively much more mucilage in the 

 young part of the stem, that is, within two or three inches 

 from the tip, than in the older parts. Actual counts and meas- 

 urements showed this, but later, in October, more material 

 was obtained and in this mucilage was not quite so evident 

 in any part, and especially not near the tips of the branches. 



The amount of mucilage is much less in sections near the 

 root than near the apices of the branches, while the starch is 

 more abundant near the root. The root contains only a trace 

 of mucilage during the growing season, while it is well filled 

 with starch at all times. In the autumn there is a slight in- 

 crease of starch in the root and a great increase in the mucilage 

 content (fig. 29). 



Crystals of calcium oxalate are very numerous in the parts 

 of material gathered in October, but that obtained in June 

 showed no trace of crystals. In material collected in early 

 spring, however, crystals were present. 



The cells of the borders of the pith are relatively small and 

 heavy-walled, while in the center of the pith the cells are much 

 larger, the walls thinner and more regular in shape, being 

 round or nearly hexagonal where they have pushed together 

 and crowded out the air spaces. In the older parts mucilage is 

 seldom found in the pith. 



LEAF. 



The orbicular leaves are borne on long, slender petioles and 

 spread out almost horizontally, except in hot or dry weather 

 when the edges curl up. They vary in size from an inch and 

 one-half to two inches in diameter. The margin is indented to 



