tuifilvsis tj be oxygen, hydrogen, and carbon, with an occasional 

 addiliuii uf nitrogen, the same simple elements as, by their 

 varied combinations, constitute the air, water, and most animal 

 substances. The organic basis is simple membrane oxidi fibre 

 Of one, or both, of these two forms, all the tissvies are con- 

 structed. 



a. K the fleshy portion of the leaf above mentioned, or the pulp of the fruit he 

 closely examined, they will be found composed of numerous vesicles of extreme 

 minuteness, adhering together. These vesicles, or bladders, consist of a delicate 

 membrane enclosing a fluid, such as is seen on a large scale in the pulp of an 

 orange. Now this membrane, composing the walls of the cells or vesicles, is one 

 of the elementary forms of vegetable tissue. ' Again, if the stalk of a strawbeny or 

 geranium leaf be cut around but not through, and the two parts be tlius jJuHcd 

 asunder for a short space, a niunber of glistening Jibrcs \\ill be seen running ft-om 

 one portion to the other. Under a microscope these appear to be spiral coils, par- 

 tially straitened by being thus drawn out from the membranous tubes in which 

 they were lying coiled up. Thus are we able to distinguish the elementary mcm- 

 hrane and fibre, of which the various forms of vegetable tissue are composed. 



29. Cellular tissue is so called, from its being composed 

 of separate cells, or vesicles, adhering together. This kind of 

 tissue is the most common, no plant being ■without it, and many 

 being entirely composed of it. The form of the little cells 

 which compose it, appears to be, at first glooular or egg-shaped, 

 but afterwards, being flattened at their si6e'<s, by their mi^tual 

 pressure, they become cubical, as in the pith, or twelve-sided, 

 the cross-section being six-sided; each cell assuming a form 

 more or less regular, according to the degree of pressure exerted 

 upon it by those adjacent. . It is also called parenchyma. 



a. The cuttmgs of the pith of elder, or those of any kind of wood, will, under 

 a microscope, exhibit irreg^ilar cells and partitions, resembling those of a honey- 

 comb. (Fig. \, a.) 



h. The vesicles of cellular tissue have no visible communications with each 

 other, but transmit their fluids by invisible pores. 



c. Cellular tissue is transparent and colorless in itself, but exliibits the brilliant 

 hues of the corolla, or the rich gi-een.of the leaf, from the coloring matter con- 

 tained within the cells. 



d. The vesicles of this tissue are extremely variable in size. They are usually 

 about -g-Tju of an inch in diameter, but are found of all sizes, from -^xs to -siyijij 

 of an inch. 



e. Although this tissue is usually soft and spongy, it sometimes acquires con- 

 siderable hardness by the deposition of solid instead of fluid matter in the cells. 



