176 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



The epidermal cells in the lower portion of the cavity which 

 underwent excessive elongation were 1.64 times as long as the normal, 

 but the normal were 1.4 times as wide as the etiolated. A similar re- 

 lation holds in the detentive area where the epidermal cells were 1.29 

 times the normal in length but the latter are 1.55 times the etiolated 

 cells in width. An increase of the actual number of cells in the etio- 

 lated detentive region was thus demonstrated. In the conducting sur- 



A 



r> s "'' ' f * ' « » 



D 



^ ' I / \ I \ 





D 



" ' ' 1,1 



ii)M 1'' ' 



1„. 1', 



I 1 



'l,,lll 



1 1 ' 



','■■" 



, ' M ' ,v 



' )inii, 1 1 



,' il ' n I I , , , , , 



I. II. 



Fig. 136. Diagram showing relative development of various regions in normal and 

 etiolated leaves. I, normal. II, etiolated. ^. terminal flap. ^, " attractive " surface- 

 C, " conducting " surface. jD, "detentive" surface. JB, cavity below detentive sur. 

 faces, i^, petiole. Drawn by Wm. B. Stewart. 



face the cells of the epidermis are 1.35 times the length of the etiolated, 

 in the normal and are also 5 times the etiolated in width, showing a 

 decrease in the number of cells. The same is true of the attractive 

 surface in which the normal is more than twice the etiolated in all 

 dimensions. Trichomes of all kinds are both longer and thicker in 

 the normal. 



