288 



MANUAL OF BOTANY 



acquire a more or less star-like shape {fig. 620) ; and hence 

 such cells are called stellate. These rays may be situated in one 

 plane, or project from all sides of the cell. It is rarely the case 

 that such cells have the rays at regular intervals, or all of one 

 length, but various degrees of irregularity occur, vyhich lead to 

 corresponding irregular forms in such cells. 



When the growth takes place chiefly m one direction, we 

 have cells which are elongated, either horizontally or vertically. 



Fig. 622. 



Fig. 623. 



Fig. 624. 



"? 



@ 



Fig 625. 



i .^ 



Fig. 626. 



Fig. 622. Elongated fusiform cells. Fig. 623. Pibrilliform cells (Iiypha'). 



Fig. 624. Transverse section of a thick-walled cell of the pith of 



Hoya carnosa. Prom TouMolil. Fig. 626. Thick-walled cells fromthefruit 



of a Palm, a, a. Cell-walls, h, b. Concentric layers of thickening, 

 c. Canals extending from the central cavity to the inside of the wall 

 of the cell. d. Cavity of the cell, e, e. External dotted appearance. 

 Prom Unger. Fin. 826. Striated fibres from bast of Lime tree. 



Of those cells, which are extended in length or verticall,^', we 

 have such forms as the cylindrical (fig. 621) and fusiform, 

 (fig. 622) : these, by the mutual pressure of contiguous cells, 

 often become prismatic. In many Fungi we have a very 

 marked form, the cells being thin-walled and very long and 

 thread-like, and either simple or branched (fig. 628). 



When the cell has attained its full size, or in some cases 



