CELLULAR TISSUE. 



11 



at an opposite one. 



Fig. 25. Elongated cells of a mushroom 

 (Boletus) resembling tubes. 



This will terminate in an elongated cell, such as those observed in 

 the mushrooms (Fungi 

 Fig. 23), and more parti- 

 cularly in a gigantic kind 

 of mushroom termed the 

 Boletus (Fig. 25), in which 

 the length of the cell ex- 

 ceeds the hreadth by many 

 diameters. In this mode 

 it is conceivable that a 

 tube might be formed 

 from a single cell, or from 



a series of cells, if placed Fig. 26. Diagram showing 

 end to end, and the parti- 



series of cells which, 

 the breaking up of their 



tions broken down, al- partition walls, are form- 

 though no satisfactory ing a tube, 

 illustration of this mode of conversion of cells into tubes has yet been discovered 

 (Fig. 26). 



The terms, oblong, lobed, square (Fig. 27), nmriform (Fig 28 ), prismatical, cylin- 

 drical, compressed, sinuous (Fig. 30), and stellated, have, 

 amongst others, been devised to indicate other forms of 

 cells than those above indicated. 



The cell varies as greatly in size as its figure ; 

 so that, on the one hand, they may be seen by the 

 naked eye, as in the pulp of orange, lemon, or shad- 

 dock ; on the other they are so minute that it is neces- 

 sary to examine them with a high magnifying power, 

 and ! poo parts of an inch in diameter. 



I I ' I 



I , I . I I 



I.I.I I I 



Fig. 27. 

 Cubical or 



Fig. 28. Muri- 

 form cells, or 

 cells resembling 

 the bricks in a 

 wall. 



square cells. 



The limits of variation are 



Some form of cellular tissue constitutes the whole of most of the lower classes of 

 plants, as the Fungi; and in all other plants it is found in the roots, or subterranean 



(as the potato, radish, and tur- 

 nip) ; in bark, pith, leaves, flowers, 



seeds, and fruit. The cuticle of 



leaves, in general, is furnished 



with cells, having a sinuous or 



wavy outline, thence termed the 



sinuous variety (Fig. 29). 



The most interesting variety of 



cell is that termed stellate, or star- 

 like, from the radiating form which 



it assumes. This is well seen in the 



rush (Fig. 30), in the sweet-burr 



reed (Sparganium ramosum Fig. 



*>). * ^ yellow water-lily (Ifu- 



phar lutea), and in many other 



water-plants of loose tissue. "We have also met with a beau- 

 tiful illustration of it in the partitions of the cells constituting the thick central parts 

 of the long leaves of the Banana tree (Jtfusa paradisaical}. The construction of this 



Fig. 29. Very irregular 

 stellate cells from the foot- 

 stalk of a leaf of the sweet- 

 burr reed (Sparganium\ra- 

 mosum). showing the la- 



Fig. 30. Star -shaped cells 

 of regular character, frdni 

 the stem of a rush, having 

 lacunae at a, bounded by 

 cell-walls, and the union 

 of the cells indicated by the 

 transverse line at the mid- 

 dle of each arm or ray. 



