44 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



increased length was not clear, unless perhaps it might be said that 

 the normal cells had not attained full growth. The cortical cells 

 were larger in the etiolated stems and presented quite a different 

 aspect, being arranged with their longer diameters radial, while in 

 the normal the greater diameter is tangential. The number of 

 layers of these cells was greater, and the individual elements showed 

 a more rounded contour, with large intercellular spaces. The normal 

 cortex has but sparing intercellular spaces, and the outline of the 

 cells in transverse section shows well-defined angles. 



Fig. 5. Surface view of epidermal cells of stems of Apios Apios: A, normal; B, 

 etiolated. X 250. 



But little difference could be found between the xylem of the 

 normal and etiolated stems. External to this however the changes 

 were most marked. The etiolated stem developed a distinct and 

 continuous cambium wdth many layers and the sieve tissue was not 

 to be made out with certainty, as in the normal. The space between 



