PHYSIOLOGY OF CELLS 



67 



Evidence From Plasmolyzed Cells. — Similar evidence comes from 

 plasmolyzed cells of leaf- and root-hairs. By placinjj; these cells in 

 certain salt solutions, the protoplasm, which normally rests chiefly 



Fig. 33. — Diagram of regeneration in Stentor. The nucleus is a beaded chain, and 

 if the animal is cut pieces of the body containing large portions of the nucleus regenerate 

 rapidly; pieces containing less of the nucleus regenerate more slowly; and pieces containing 

 none of the nucleus die and disintegrate without regenerating. 



against the cell wall and encloses a liquid in its otherwise hollow interior 

 (Fig. 24), may be made to shrink up into much smaller volume by the 

 withdrawal of the interior liquid. Frequently in this shrinkage the 

 protoplasm is divided into several masses, which may be entirely separated 



Fig. 34. — A plasmolyzed cell. On immersing the cell in a salt solution the protoplasm 

 shrunk into several more or less distinct masses. Each mass containing a nucleus or 

 connected by a fine filament of protoplasm with a nucleated mass produced about itself 

 a cell membrane. Other masses remained naked. (Modified from Townsend.) 



from each other or may be joined by fine strands of protoplasm, as shown 

 in Fig. 34. Those portions of the cell which contain the nucleus, or are 

 connected with the nucleated piece by the fine strands of protoplasm, 

 form about themselves a new cell membrane, grow, and live normally. 

 Even a connection with a nucleated fragment of an adjoining cell, through 

 fine pores in the cell wall, suffices to maintain the normal functions. 

 The non-nucleated fragments, if entirely separated from nucleated 



