112 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



an elevation on the surface of the leaf by a single thickening of 

 the outer cutinized layer. Such thickening was wholly lacking in the 

 etiolated leaf, and the guard cells are slightly sunken below the sur- 

 face. The guard cells do not undego full differentiation, and the 

 supporting cells were smaller than in the normal, being functionally 



Fig. 69. Gas/en'a disticha. Same plant as in Fig. 67, 14 months after confine- 

 ment in dark room. The leaves formed in light have perished and the younger etio- 

 lated leaves are held in various aberrant positions due to ruptures in the stem. 



active however, as attested by the long endurance of the etiolated 

 leaves. The parenchyma cells of the normal leaf are richly loaded 

 with starch and chlorophyl, which were entirely lacking in the 

 etiolated organs, the plastids present being much smaller than the 

 normal. 



The growth of the etiolated specimen continued until Feb- 

 ruary, 1902, at which time it was damaged in handling and per- 

 ished. 



