ISO 



MEIVIOIRS OF THE NEW YORK BOTANICAL GARDEN. 



or three in other places. The cortex was composed of extremely thin 

 walled elements with some intercellular spaces. 



The protoxylem was fairly normal but the woody tissue was 

 very imperfectly developed, while the formation of the secon- 

 dary wood ring and xylem had only progressed so far as to show 



Fig. 109. Phytolacca decandra. Structure of etiolated stem. A, epidermis; B, 

 collenchjma; C, cortex; D, bast fibers; E, location of secondary cambium; F, cam- 

 bium; G', xylem; //, surface view of epidermis, showing one prestomatal cell. 



groups of elements with denser contents in the positions of the 

 vessels, and the presence of a layer of cambiform calls external 

 to them. Numbers of elongated lenticellular ridges appeared on 

 the basal portion of the stem in the region from which the leaves had 

 fallen. 



The comparatively brief duration of the shoot was coupled with 

 the non-formation of stomata on the stem. 



Podophyllum peltatum L. 



Rootstocks of Podophyllum were brought into the dark room at 

 various times and the leaves and flowers allowed to develop. 



Petioles showed an elongation about 80 per cent, in excess of the 

 normal and the epidermal elements were correspondently elongated. 

 The lobes of the centrally peltate leaves were about one third the 

 length of the normal, and were folded with the under surfaces together, 

 the whole etiolated laminae having the form of a partially opened 

 umbrella. Stems bearing both leaves and flowers reached a length 

 about double the normal in darkness, and the flowers were fairly 

 normal in structure opening partially. The lack of functional ma- 

 turity of the stomata was accompanied by a brief duration of the 

 leaves and stalks, and the etiolated organs soon perished, resting 



