PROTOPLASM 265 



the large volume of the cell occupied by the vacuoles. The 

 protoplasm in this case will consist probably only of the 

 lining layer of cytoplasm in which the nucleus is imbedded. 

 Examine the leaf of the water plant elodea or the thin 

 leaves of some of the mosses. Note the character of chloro- 

 plasts in the cells (Fig. 439). These chloroplasts may 

 be observed in the cells of the leaf of higher plants if a 

 cross-section of the leaf is cut and a microscopical examina- 

 tion made. Study should be made of cells of the soft pulp of 

 a celery stem; of hairs scraped from the surface of a begonia 

 leaf; of threads of spirogyra; soft, white cells of apple; the 



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7 



439. Rotation of protoplasm in Elodea canadensis (often known as 

 Anacharis). Common in ponds. 



cells of the potato tuber (observe the starch grains). Ex- 

 amine the lower epidermal cells of cyclamen, irises, or coleus 

 and note that the cell-sap is colored by a red pigment. 

 The beet also has cells with red pigmented cell-sap. 



441. Nature of Protoplasm. — The living substance is 

 protoplasm. It is proteid. Its chemical composition is not 

 known. It is semi-liquid, of hyaline color, and colloidal in 

 nature. It may be killed by heating to a high temperature 

 or by various chemical reagents. The whole principle of 

 antiseptics is based on these facts and processes. 



442. Within the cell-wall, at times the protoplasm 

 shows a tendency to move from place to place. This move- 

 ment is chiefly of two kinds: (1) Circulation, or movement 

 not only along the walls but also across the cell-body, as seen 

 in the long, thin-walled cells of celandine; in the staminal 

 hairs of tradescantia (Fig. 438); in the bristles of squash 

 vines; in the stinging hairs of nettle; in stellate hairs of holly- 

 hock. (2) Rotation, or movement along the walls only, well 



