254 



w 



M 



question at once arises. By what process is their substance taken 

 up into the wall ? There is little probabihty that the latter 

 stretches out so as to use up this material, as in the case of the 



cellulose ring in the CEdogonhim cell. The shape is not adapted 

 to this purpose, therefore a process similar to that of intussuscep- 

 tion must take place. The assumption that this is the function 

 of these globular bodies, and that they arc merely reserve stores 

 enabling the outer wall of the epidermis to preserve its uniform 

 thickness, we admit, rests on very slight proofs. There are, how- 

 ever, several indications which point in this direction. 



• Chemically, they agree perfectly with the outer wall from 

 which they extend. The greater portion of this wall consists of 

 cutin in its early stages, a layer of pure cellulose is found to ex- 

 tend along the inner surface connecting with the side walls, and 

 • this cellulose extends entirely around the sphere. In fact, it is 

 as though a little bag of cellulose membrane were sunken in here 

 and filled with cuticularized substance. There is no question as 

 to its chemical nature, as it was repeatedly and thoroughly tested. 

 Again its connection with the new young wall is suggestive of this 

 function. Except for this, its appearance is quite similar to th 

 incrustations of calcium carbonate sometimes found in the epider- 

 mal cells q{ Ficus* However, cystoliths do not occupy such a 

 position in reference to new walls, neither do they consist of cu- 

 ticularized cellulose. Another reason for the assiunption is the 

 lack of these bodies in the epidermis of the grown stem, or that 

 portion where the \\q\m periderm Is about to form and the epider- 

 mis is to be thrown off. 



EXPLANATION OF PLATE CIX. 



J 



Figures J, 2 and 3 represent cross sections of stem of Kuonynitis angusiifolia^ 

 var. pitrpitrea. They Include only a corner in each uistance, containing a bundle of 

 bast cells, which appears in fig. 3 in a mature or finished condition. 



Fig. i shows a section cut une-half centimeter below the tip of the stem, fig. 2 

 three centimeters, and hg. 3 twenty-five centimeters from tliis tip. In each of the; 



e 



figures a marks epidermal tissue, b the subepiiiermal or supporting-cells, and V tliose 

 holding chlorophyll. 



In fig. I, i marks the collencliymatic cells of the corner, which later on develop 

 into bast fibers. In fig. 2, these cells c are thin-walled, and have a larger lumen. 

 In fig. 3 the same letter marks the cluster now completed. 



Fig. 4 represents the epidermal layer as seen from above— distance from tip of 



^See Ilaberlandt Physiologische rilanzen Anatomie, page 340. 



