MEMOIRS OF THE NEW YORK BOTANTCAI. GARDEN. 45 



the cambium and the bast fibers was occupied by a mass of elongated 

 parenchymatous cells with large lumina. The bast fibers were to be 

 made out but were very sparingly thickened. Externally to the bast 



B 



D 



E 



F 



G 



Fig. 6. Aptos Apios. Transverse section of portion of aerial normal stem; A, 

 epidermis; B, cortex; D, bast fibers; E, cambium; F, xylem ; G, pith. X^O- 



was a tract of two to five layers of cambiform cells which seemed to 

 be very active. The formation of this secondary generative region 

 is certainly a remarkable occurrence, and is one which finds a paral- 

 lel only in Castanea., Hicoria and ^tercus among the species 

 examined (see Fig. 7, C). 



Fig. 7. Apios Apios. Transverse section of portion of etiolated stem; A, epi- 

 dermis; B, cortex; C, generative layer; Z>, bast fibers; E, cambium; F, xjlem ; G, 

 pith. X40- 



