74 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



The true leaves, which appear as bracts subtending the cladodes, 

 were somewhat larger in the etiolated examples, and are almost pure 

 white in color. 



Normal stems show a ver}' irregular outline in transverse section 

 due to the unequal thickness of the cortex, which is not fully illus- 

 trated by Fig. 29. The etiolated stems are variously compressed 

 from a cylindrical form, but the curves in the cross-section are not 

 so sharp or crooked. The cells of the etiolated epidermis are some- 

 what elongated, and this layer is furnished with stomata apparently 

 functionally normal. The epidermal cells are larger in all transverse 



Fig. 28. Terminal portion of etiolated shoot of Asparagus ojicinalis with, branches. 

 This shoot has fallen prostrate and the apex has curved upward geotropically- 



diameters than the normal and the outer wall lacks the outer thick- 

 ening layer. The etiolated cortex is also composed of much larger 

 elements than the normal, which assume more rounded forms, and 

 are furnished with greater air-spaces. The walls of the normal 

 cortex are much heavier than in the etiolated. The marked increase 

 in the diameter of the etiolated stem is to be attributed chiefly to the 

 exaggeration of the cortex, although the fundamental parenchyma 

 may participate to some extent in the matter. It is noticeable, how- 

 ever, that the central lysigenous cavity of the normal stem is lack- 

 ing in etiolated organs. The normal stem has a heavy pericycle 



