QR0TJP8 Of TISSUES, OB TIS8UB- SYSTEMS. 47 



this and allied species the bundles are curiously isolated 

 from the surrounding ground-tissues of the stem. 



88. The fibro-vascular bundle of the underground stem 

 of the common Brake-fern (Pteris) is composed of trache- 



Fia. 30.— Magnified eross-sectiou of the stem of a smaller Club-moss (Selagi- 

 nella inseouifolia), showing three bundles. 



ary, sieve, and soft tissues and a small amount of poorly 

 developed fibrous tissue. In transverse section the bundle 

 has usually an elliptical outline. The great mass of the 

 bundle is made up of large scalariform vessels, which 

 occupy its interior {g, g, g, Fig. 31). Enclosed in the sea- 



