298 BOTANICAL GAZETTE [october 



cells thick is present, whose outermost wall is the former external 

 wall of the old epidermis. The tissue developed in this way is 

 eventually entirely cut off, and a new outer epidermal wall is 

 cutinized, so that the new epidermis resembles that which has 



just been lost. 



The stomata were of the regular dicotyl type (fig. 4) and 

 numbered 32-36 per sq. mm. of surface. Because of the thick 

 cuticle they were sunken below the surface of the shoot (fig. 14). 

 Below the epidermis extended the hypoderm, about six cells in 

 thickness (figs, n, 14). The first layer of the hypoderm consisted 

 of a sheet one cell thick, with a large crystal of calcium oxalate in 

 almost every cell. The remainder of the hypoderm was made up 

 of about five layers of stone-cork cells. In places the crystal- 

 containing cells almost closed the air chambers just under the 

 stomata. The stone-cork cells were deeply pitted. They gave 

 place abruptly to the palisade tissue with its long tubelike columns 

 of cells, which was followed by the spongy cortical region reaching 

 to the stele. The most external chloroplasts occurred in the 

 palisade cells, where they were numerous on the lateral and end 

 walls. Large air chambers extended from the stomata inward 

 through the hypoderm into the palisade tissue, and the inter- 

 cellular spaces were extensive in both palisade and spongy inner 

 cortex. The structure of the stele will be described in a future 



paper 



Etiolated shoot 



marked 



contrast with that of the normal ones (fig. 1). They were pinkish 

 at first, but later changed to a very light green. They were longer 

 than the normal shoots and more or less flattened in cross-section 

 (fig. 3). Numerous sessile leaves like those of the normal plant in 

 form were produced, which persisted for a short time. The longest 

 measured was 7.5mm. Spines, bristles, and glochids were 

 grouped in a normal manner but were reduced in size, the spines 



g 3 mm. in J 

 intermediate 



normal plant, the epidermis 



shoot was without cuticle (fig. 13), although the walls showed 



