THE DIFFERENTIATION OF THE PLANT-BODY 27 
(fig. 80); the vascular bundles of many Monocotyledons 
are surrounded separately by a sheath of small cells of 
similar character (fig. 81); in Pennisetum (fig. 82, 4) a 
sheath is developed round the stem in the form of a hollow 
cylinder which lies between the bundles and the epidermis. 
More frequent instances occur in which two of the 
regions in question are strengthened simultaneously. In 
the stems of Scirpus (fig. 82, 5) there is a development of 
sclerenchyma round the periphery, and strands occur also 
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Fic, 30.—Lrar oF Pinus (ONE OF THE CONIFERS) 
ep, epidermis; Jy, layer of sclerenchyma ; en, endodermis; v.b, vascular 
bundle ; 7d., resin duct. ; 
in connection with the bundles. Sometimes these are con- 
nected by bands of sclerenchyma lying between them. In 
Fimbristylis (fig. 32, 7) there is a ring of sclerenchyma in 
the cortex and patches around the periphery, which in other 
cases are joined like those of the former type. Inthe stems 
of Typha. (fig. 82, 9) a band of sclerenchyma lies at the 
back of each bundle, and either a ring or some isolated 
strands may be found in the cortex. The stem of Juncus 
(fig. 82, 10) shows these two forms combined together. 
Still more complicated cases show sclerenchyma arising 
