6 PRACTICAL BOTANY. 



21. The ANATOMICAL ELEMENTS of the Vegetable organ- 

 ism are the Cells. 



When we properly examine by the microscope delicate 

 slices of any of the parts of a plant, they will present a 

 network, the meshes of which circumscribe little sacs or 

 bladders, primarily of a spherical shape, but in time be- 

 coming very various, as polyhedral, oblong, cylindrical, or 

 even tubular. The ordinary diameter of the cells is be- 

 tween -gL- to xfo of a line. 



3S. A young and vitally active cell consists of the fol- 

 lowing parts : a, a thin, colorless, transparent memhraney 

 which incloses and forms a cavity, and is lined by a soft 

 and mucilaginous film, called th.^ primordial utricle ^ h, a 

 jelly-like Tieniel (nucleus) in the centre of the cavity ; and, 

 finally, (?, a liqitid, known under the name oi protoplasm^ 

 whicli fills the rest of the cavity. 



23. All the cells of a plant constitute the elementary 

 fahric^in which the products sustaining life are prepared. 

 The combined vital action of all the cells of the vegetable 

 composes what we call vegetable life. The cell is the fac- 

 totum, without which the existence of plants would be im- 

 possible. It manages the affairs of the whole economy of 

 any vegetable individual. 



24. Each cell is a chemical laboratory, which supports 

 vegetable life. The cell is the true propagator of plants ; 

 it chains vegetable individuals to one another, thus estab- 

 lishing the constancy of the several species. It is also the 

 Proteus, which creates genera, orders, and classes, and, 

 finally, the parent of the whole vegetable kingdom. 



25. The lowest plants are single cells. Such a plant is 

 destitute of any external organs. It imbibes its food 

 through its membrane, to assimilate it in its cavity, and 



