BAST—LIBRIFORM CELLS. 199 
The great mechanical service which the bast-cells are capable 
of was also recognized at an early period. The application of 
the bast-fibres of hemp and of flax (Fig. 113) for fabrics is a 
very ancient one. 
The textile fibres which are practically employed may be 
grouped in the following manner (compare Fig. 114): 
1, Animal fibres: (a) hairs, Wool (W); (b) threads, Silk (S). 
2. Vegetable fibres: 
(a) hairs, Cotton (B). 
(b) bast-cells, Flax (L); Hemp (H); Jute (J); Esparto; 
Manilla-hemp.* 
In addition to the bast-fibres, the libriform cells of the 
wood also assume, especially in the older stems of dicotyledons, 
Fig. 115,——A, Sclerenchyma from the inner layer of the seed vessel of Fructus Cocculi 
(Cocculus Indicus). B, Some branched cells of the same, more highly magnified. 
a mechanical function. The bast-cells which occur in the bark 
of dicotyledons (hemp, flax, Fig. 113, the linden) are only of 
service in imparting strength of flexure to the stem as long as 
the wood itself has not yet acquired sufficient strength. 
In accordance with the various mechanical demands made of 
the plant, the structures in which the mechanical elements are 
‘Compare especially Wiesner, ‘‘ Die Rohstoffe des Pflanzenreiches.” 
Leipzig, 18738. Reissek, ‘Die Fasergewebe des Leines, Hanfes, der 
Nessel und Baumwolle.” Denkschr. d. Wiener Akad., 1852. Berthold, 
“* Ueber die mikroskopischen Merkmale der wichtigsten Pflanzenfasern.” 
Zeitschr. f. Waarenkunde, 1883, No. 8; 4. Dorkoupil, ‘* Materialien zu 
einem Lehrbuch der chemischen Technologie fiir Gewerbeschulen.” 
Jahresber, d. Gewerbeschule Bistritz, 1882. 
