SCLERENCHYMATOUS FUNDAMENTAL TISSUE. 



145 



vascular bundles. In the long, thin, and yet very elastic and firm flowering scapes 

 of Rushes {/uncus, Scirpus, Cladium, etc.), lignified sclerenchymous strands either 

 run close beneath the epidermis, or a closed ring of that tissue lies in the neighbour- 

 hood of the periphery, and gives the slender column the necessary rigidity. 

 Schwendener, who first called attention to the significance of these sclerenchyma 

 layers and strands with reference to the elasticity and rigidity of the organs concerned, 

 distinguished their cells as bast-cells. This nomenclature, however, has not been 

 accepted by botanists : the name bast was given long ago to the elastic fibres in the 



Fig. 154. — Transverse section of a fibro-vascujar bundle from the stem oi Zea Mays (Indian Com) surrounded by its 

 sheath of sclerenchyma: a is towards the exterior, gndz towards the centre of the stem, ^large-celled parenchyma of the 

 fundamental tissue. Only the parts w (sieve-tubes), ^(pitted vessels), j (spiral vessels), »- (annular vessels), and the elements 

 lying between these constitute the vascular bundle — the thick-walled shaded tissue is the sclerenchymatous sheath. 



phloem of the vascular bundle and the secondary cortex. Generally speaking, this 

 true bast is not hgnified, its long fibres being rather distinguished in fact by their 

 flexibility. Besides, plenty of examples occur where the sclerenchyma layers described 

 consist of cells which cannot be in any way compared externally with bast-fibres : the 

 sclerenchyma cylinder in the flowering scape of species oi Allium (Fig. 155 jr.), for 

 instance, consists of cells transversely or obliquely truncated above and below, the 

 relation of which admits of no doubt whatever that the entire sclerenchyma ring is 

 only a layer of narrower cells of the parenchymatous fundamental tissue, which is 

 [3] 



