GNETALES 



359 



incorporated in the large ray, for fibers are also present, although 

 they cannot be so well recognized in the transverse section. The 

 constitution and 

 origin of the large 

 rays in Ephedra are 

 of great signifi- 

 cance, not only for 

 the Gnetales them- 

 selves, but also in 

 connection with the 

 problem of the evo- 

 lution of the higher 

 forms known as 

 dicotyledonous an- 

 giosperms. It will 

 accordingly be con- 

 sidered somewhat 

 in detail. 



Fig. 257 illus- 



trates the organiza- 



FIG. 256. Transverse section of the wood of Ephedra 

 species. 



tion of the large ray 

 in an early stage of 

 development when 

 it is still rather nar- 

 row and close to the 

 medullary region of 

 the stem. An in- 

 spection of the illus- 

 tration makes it 

 clear that the ray is 

 by no means a 

 homogeneous struc- 

 ture composed 

 entirely of storage 

 parenchyma. Fi- 

 brous elements 

 necessarily enter 



FIG. 257. Longitudinal section of a large ray of 

 Ephedra in proximity to the pith. 



