Ramaley : HYPOCOTYL AND EPICOTYL IN WOODY PLANTS. 101 



These stereom bundles bend outward and accompany the corti- 

 cal bundles in succeeding internodes. 



The pith is rather thick-walled ; the cells are about the same 

 size as those of the cortex. A small-celled perimedullary zone 

 of one or two layers is at length clearly distinguishable. 



Cork formation begins very early in the outermost sub-epider- 

 mal layer of the cells. 



Structure of EpicotyL 



The cells of the epidermis when seen in cross section are rec- 

 tangular with the long diameter parallel to the surface of the 

 section. There are numerous pointed hairs of various lengths. 



A collenchymatous hypoderma, four or five layers of cells in 

 thickness, forms the outer part of the cortex, the rest of which is 

 composed of very loose parenchyma. 



A definite endodermis was not distinguished. The endoder- 

 mal region is, however, easily recognized by the presence of 

 starch in many of the cells. Starch is afterward found in great 

 abundance in pith, cortex and medullary rays. 



The normal phloem and xylem form closed rings even in the 

 youngest material examined. In the cortex, about half way 

 between the epidermis and phloem are four vascular bundles, 

 ninety degrees apart ; each bundle consists of a more or less 

 crescent-shaped mass of lignified sclerenchyma, at whose con- 

 cave surface is a small .area of slightly lignified xylem, consist- 

 ing usually of five to ten cells. Adjoining this xylem and pro- 

 jecting some distance toward the stele is a lenticular mass of 

 phloem. The general arrangement of the bundle is the same 

 as that carefully described for Calycanthus sp. by Woronin 

 [1860] and for Calycanthus occidentalis by Williams [1894]. 

 Serial sections showed that in this species these cortical bundles 

 enter the stele about i mm. below the insertion of the cotyledons, 

 and not at the middle of the first internode as reported by Herail 

 [1885] for certain other species. 



The pith is large. There is a definite perimedullary zone of 

 about three layers of small cells. 



The cork cambium is formed very early in the outermost 

 hypodermal layer (cf. Moeller [1882], p. 364). 



Comparison of Structure of Hypocotyl and EpicotyL 

 The epidermal hairs of the hypocotyl are fewer and shorter 



