84 



A. H. Graves, 



1. As would be expected, no cortical leaf trace bundles are 

 present. 



2. The central vascular area is very similar to that of the stem. 

 The tracheae in the center are pretty well disorganized, which is 

 natural when one calls to mind the considerable extension of the 

 peduncle. 



3. The lacunae are more numerous and much larger in proportion 

 to the diameter of the peduncle than in the stem (Text-fig. 9 ; PI. VI, 

 fig. 34). 



4. In comparison with the stem the epidermis has slightly thicker 

 walls, and small intercellular spaces may occur between it and the 

 subjacent layer, an appearance which one never sees in cross sections 

 of the stem (Text-fig. 10). 



5. Occasionally some of the epidermal cells have a peculiar 

 halved appearance, as if a periclinal wall divided an ordinary ep- 

 idermal cell into two parts. This is due probably not to a division 

 in the epidermal cell, but to the fact that a small subepidermal cell 

 is wedged up close to a small epidermal cell (Text-fig. 10). 



Eigure 10. — Portion of cross section of peduncle ; x, apparent- 

 ly double epidermal cells ; /<?, lacunae ; /, intercellular spaces. 

 X 300. 



On the whole, the main differences between this structure and 

 that of the ordinary stem are its lack of cortical bundles and its 

 lighter construction. The latter is explained when one recalls the 

 fact that the peduncle for a great period of its existence floats, 

 and hence its specific gravitj^ must be small. 



