78 VIEWS OP THE MICROSCOPIC WORLD. 



Fig 117. Fig. 118. Fig. 122. 



Fig. 119. Fig. 120. Fig. 121. 



series of cups or beads strung together, the surface of the several parts being 

 studded with minute projections. The spiral structure is again seen in the 122d 

 figure, and the characteristics of figures 117, 118, and 121, are here likewise 

 recognised. 



CELLULAR TISSUE. The tubes just described are bound together by a tissue 

 filled with minute cells, which has thence been denominated the cellular tissue. 

 It is a constituent part of every organ of the more perfect plants, and in many 

 herbs forms the principal portion of their substance ; while the lower order of 

 vegetables, as mosses, mushrooms, <fec., are said to consist of it entirely. 



The appearance which this tissue presents is extremely diversified. At one 

 time it is seen to be of a loose, porous texture, every part of which is transparent 

 and succulent. Under other circumstances, it meets the eye in the condition 

 of a solid body, the cells being so closely pressed together that the peculiarity 

 of its structure is almost lost. In a third case the cells likewise vanish from an- 

 other cause, for the tissue then spreads out into a membrane so extremely deli- 

 cate and thin that all traces of their existence disappear. The cells or cavities 

 of the cellular tissue are generally arranged in a direction opposite to that of the 

 tubes of the vascular system, and are therefore displayed in the longitudinal 

 and not in the cross section of a plant. 



The forms of the cells are exceedingly various. In some plants they are of a 

 globular shape, in others angular, but differing as to the number of sides ; seve- 

 ral kinds being triangular, others square, but the greater proportion exhibit hex- 

 agonal 01 six-sided figures. 



