THE PBINOIPAL TISSUES. 



73 



(d) Theliard tissues of uutsand of Btone fruits furnisli excellent ex. 

 amples of short and very thick-walled sclerenchyma-cells. In the 

 hickory nut {Garya alba) the cells (Figs. 58 and 59) are not more than 



Fio. 68. 



Kg. 58. — Sclerenchyma-cells of the shell (endocarp) of the hickory-nut (Ozrj/a 

 alia), taken parallel to the surface of the nut. X 400. 



Fig. 69.— Sclerenchyma-cells of the shell (endocarp) of the hickory-nut (Carya 

 atita), taken at right-angles to the surface of the nut. X 400. 



two or three times as long as broad, and the thickening is so great as 

 almost entirely to obliterate their cavities; the thickened walls are 



Fig. 60. 



Fia. 61. 



Fig. 60.— Sclerenohymacells of the seed-coat of Echlmcyetis lobata, from a section 

 at right angles to the surface of the seed ; a, a cell cut directly through its centre 

 showing the whole of the cavity-the three dark spots are probably oil : 6 a cell 

 cut through at one side of the middle ; c, a cell whose cavity was not cit into in 

 m^ing the section. X350. From a drawins by J, C. Arthur 

 „.fifi'.?V~;v"''^'^J2''^y".*'5?"^ "',"'« seed-coat of Echinocyslis lobata, from a section 

 parallel to the surface of the seed, x 830. From a drawing by J. c! Arthur. 



pierced by many deep pits. The cells are arranged with their longer 

 axes perpendicular to the surface of the nut, and are very cloaelv 

 packed toffether. 



