THE DIFFERENTIATION OF THE PLANT-BODY 29 
cells of curious shape which extend from one epidermis 
to the other. Others show bands of sclerenchyma sup- 
plementing the veins and not infrequently enclosing them 
and reaching the epidermis on each side. 
The supporting tissue is frequently known as the 
stereome of the plant. It forms, as we have seen, the most 
prominent part of the endo-skeleton. 
Fic. 32.—DIaAGRAM SHOWING THE CHIEF DISPOSITIONS OF THE SKELETAL 
APPARATUS IN A STEM WITH FivE CoLLATER’L BUNDLES (IN TRANSVERSE 
SEcTIon). 
(The sclerenchyma is black ; the bast of the bundles is white ; 
the wood is dotted.) 
1, Type without accessory sclerenchyma; 2, Equisetum; 3, Bambusa; 
4, Pennisetum; 5, Scirpus; 6, Erianthus; 7, Fimbristylis ; 9, Typha; 
10, Juncus; 14, Cladium. (After Van Tieghem.) 
The cells of which the masses of sclerenchyma are 
composed have been ascertained to possess almost as much 
power of withstanding longitudinal strain as the finest 
steel, and they are much more ductile than either this 
metal or wrought iron. Their arrangement in the different 
ways described has a very distinct relationship to the 
character of the strain they have to resist. In such 
structures as hollow stems where there is but little 
substance of tissue, but where they are required to resist 
