230 



PRACTICAL BOTANY. 



the ring of xylem 

 into four parts, 

 or bundles, which 

 are, however, con- 

 nected by the cam- 

 bium layer which 

 ]\f forms a complete 

 ring. The cam- 

 bium in the bun- 

 dles is called fas- 

 cicular cambium ; 

 that between the 

 bundles, interfas- 

 cicular cambium. 



FIG. 149. -Transverse section of mature Yellow o , . - . , 



Birch, showing part of three annual layers. M, 



M, medullary rays; S, S, scalariform vessels. of the Cortical pa- 



renchyma, and just outside the inner phloem, are irregular 

 patches of dens- 

 er tissue ; these 

 are bundles of 

 bast fibers, and 

 associated with 

 them are latex D 

 tubes or laticifer- 

 ous vessels. The 

 latex tubes are 

 not, however, 

 confined to the 

 bundles of bast 

 fibers, but 

 spread as a very 

 delicate network 

 throughout 

 nearly all the tis- 

 sues of the stem. 



B 



FlG. 150. Transverse section of stem of Pipe?' futo- 

 kadsura. D, D, the normal ring of fibrovascular 

 bundles ; B, B, the second ring of bundles ; C, the 

 hollow center of the stem. Anomalous. (X 35.) 



