BOTANY. 



(e) The seed-coat of Echinocystis Idbata is composed almost entirely 

 of sclerenchyma (Fig. (30). The cell-walls are greatly thickened, and 

 the cells are very closely packed together, so much so that all are 

 sharply prismatic (Fig. 61). 



102. Fibrous Tissue. This is composed of elongated, 

 thick-walled, and generally fusiform elements, the fibres 

 (Figs. 62 and 63), whose walls are usually marked with 

 simple or sometimes bordered pits. These elements in cross- 

 section are rarely square or round, but most generally three 

 to many-sided. They are found in, or in connection with, 

 the fibro-vascular bundles of Pteridophytes and Phanero- 

 gams,and give strength and hardness to their stems and leaves. 



FIG. 62. FIG. 63. 



Fig. 62. Wood fibres of Acer dasycarpwn. isolated by Schnlze's maceration, a, 

 four fibres, X 95 ; b, a portion of a fibre, X 230, showing the diagonally placed elon- 

 gated pits ; c, the ends of eleven united fibres, X 95. 



Fig. 63. Bast fibres of Acer dasycarpum, isolated by Schnlze's maceration, a, a 

 fibre, x 95 ; 6, a portion of a fibre, X 230, showing the much-thickened wall. 



Two varieties of fibrous tissue may be distinguished, viz., 

 (1) Bast (Fig. 63), and (2) Wood (Fig. 62). The fibres of 

 the former are usually thicker walled, more flexible, and of 

 greater length than those of the latter. In both forms the 

 fibres are sometimes observed to be partitioned.* 



* These partitions have generally been considered as formed subse- 

 quently to the fibres ; but it may well be questioned whether, in some 



