Elementary Biology, 



colour (fig. 46). From this layer may be given off uni- or 

 multicellular hairs, technically called trichonies. These 

 may be simple and hair-like, but frequently take on the 

 appearance of sessile leaves (ramenta). 



Enclosed by the epidermal layer on all sides lies the 

 fundamental tissue, which composes the main mass of the 

 stem, and which is modified differently in different parts of 

 the section. Immediately beneath the epidermis lies the 



subepidermis, consisting of 



FIG. 45. TRANSVERSE SECTION OF THE _ p _ .1 l nvpr c n f t v,j r l, W o11 Pr | 



RHIZOME OF p tens aguiiina. several ia) ers or micK-^ ailed 



cells, or sclerenchyma, gra- 

 dually shading off into the 

 general thin-walled paren- 

 chyma of the fundamental 

 tissue. The epidermal and 

 subepidermal cells are filled 

 only with water or granular 

 debris ; the parenchyma of 

 the fundamental tissue, on 

 the other hand, contains nu- 

 cleated granular protoplasm 



a, fundamental parenchyma; l>, epider- and Starch grains closely ap- 

 mal hair; c, cortex ; d, fibro-vascular ^i.-^j f ~ t Vi~ ^ii ... O ii TJ~,.~ 

 strand ; e, sclerenchymatous strands. pll< a 10 me CCll-wail. 1616 



and there in the fundamental 



tissue are to be seen groups of sclerenchymatous cells, 

 with thickened cell-walls. Such sclerenchyma not infre- 

 quently takes on a horse-shoe or other characteristic shape. 

 Most important of all, however, are the fibro-vascular 

 strands, which are plunged irregularly in the fundamental 

 tissue, and are variable in size. In transverse section one 

 of these strands shows externally, and next the fundamental 

 tissue a layer of cells known as the endodermis (fig. 47). 

 These cells are formed from the fundamental tissue and are 

 dead in the sense of containing no protoplasm ; their cell- 

 walls have been modified and form a definite boundary 

 for the fibro-vascular strand. Immediately within the en- 



