2l6 



BOTANICAL GAZETTE 



[SEPTEMBER 



outnumber the latter, which occur here and there in short tan- 

 gential rows between the bast. 



First cortical cylinder. — The most intensive study of the 

 cortical cylinder was made from preparations of the innermost 

 one near the apex of the stem (fig. 3). Here details could be 

 observed where the cylinder was in an early stage of development, 

 and where its character could best be determined. 



Fig. 7. — Cycas media: transverse section of stem, showing region of protophloem 

 of innermost cylinder; ph, protophloem; b, suberized bast fibers of secondary phloem; 

 st, sieve tube; c, cells of cortex; X235. 



Fig. 8 shows a transverse section of the entire cylinder, 

 together with regions bordering it on both inner and outer bound- 

 aries. Apparently no protoxylem is present in these bundles. 

 Cells at the centripetal limit of a bundle are not different from 

 those nearer the cambium; there is little or no difference in size, 

 shape, and thickness, in alignment, or in the character of cell 



