134 



THE TISSUES. 



658. THE STARCH of the plant also originates here, in the form of 

 little striated granules of the same composition as cellulose (C 24 H so 

 O 20 ). Some 20 such granules appear in the same cell, either loosely 

 or compactly filling it. Starch is nutritive matter, sealed up for pre- 

 servation and future use. 



579 583 584 585 532 



580 531 586 



Contents of cells. 579, Cells of Potato containing starch grains. 580, Starch grains from the 

 potato ; 581, from the E. Indian Atrow-root. 582, Raphides, acicular crystals, in a cell of Poly- 

 anthes tuberosa. 583, Crystals in a cell of Cactus. 584, Cells from the pulp of Pear, coated in- 

 ternally ; a longitudinal section ; 585, Transverse section. 586, Starch granules from W. Indian 

 Arrow-root 



659. Gmf, SUGAR, SALTS, acids, alkalies, poisons, medicines, whatever is pecu- 

 liar in the properties of each vegetable substance, may also be held in solution in 

 the cell-sap and invisible, unless forming 



660. RAPHIDES, little bundles of crystals, acicular or of some other form, seen in 

 the cells of rhubarb, Cactus, Hyacinth. 



661. THE DEVELOPMENT OP NEW CELLS in the plant is the process of its growth. 

 This is accomplished within the pre-existing cells and by the agency of their con- 

 tents. The primordial utricle divides itself into two or more utricles, by septa 

 growing from its sides until they meet. These then acquire the cellulose layer out- 

 side, the cytoblast inside, at the expense of the old cell, which shortly gives place 

 to its new progeny. Thus cells multiply, and by millions on millions build up the 

 fabric of the plant. 



CHAPTEK II. 



THE TISSUES. 



662. ONE-CELLED PLANTS. The cell, as heretofore described, is en- 

 dowed with a life within itself. It can imbibe fluids, nourish itself, and 

 reproduce others like itself. It may, therefore, and actually does in 

 some cases, exist alone as a plant ! Many species of the Confervoids 

 and Diatomes are plants consisting of a single cell the simplest possi- 

 ble form of vegetation. 



663. PLANTS MANY-CELLED. With a few such exceptions, vegetation 

 consists of a combination of cells united in a definite manner and form. 



