Martin: Effect of concentrated solutions 419 



(i) ;//4 potassium nitrate produced plasmolysis in the cells 



near a vein, but the action was very irregular. 

 (2) ;//3 potassium nitrate produced plasmolysis in the cells as 



a whole. 



'16 



nj6 potassium nitrate produced very slight plasmolysis in 

 • a f^\N cells, but nj^ potassium nitrate plasmolyzed nearly 

 all the cells, some quite strongly^ thus showing that njS 

 urea was not strong enough to increase the concentration 

 of the sap, 



Acetamid. 



(i) nj^ acetamid was determined as the isotonic concentra- 

 tion. Sections which had been plasmolyzed by nj^ aceta- 

 mid were replasmolyzed by ;//5 potassium nitrate. 



(2) ;//5 acetamid plasmolyzed some cells, but the action was 

 slow due to the weakness of the solution. ;//5 potassium 

 nitrate was required to plasmolyze such sections. 



Beta vulgaris 



Free-hand sections were cut from a red beet and mounted in 

 a drop or two of the plasmolyzing solution, under a cover-glass. 

 The cells near the epidermis were found best to work with, since 

 they were of a deep-red color, and readily showed any change of 

 position of the plasmatic membrane. But the paler parenchyma- 

 cells were also considered. 



r 



Potassium nitrate. Isotonic concentration, 



(i) nl2 potassium nitrate produced slight plasmolysis in some 



cells of red beet. 

 (2) 2;//3 potassium nitrate produced plasmolysis in all cells; 



plasmolyzed strongly. 



Glycerine, {a) Isotonic concentration, — 2///3 glycerine was 



found to be the isotonic concentration. 



{b) Increase in concentration of cell-sap. — In carrying on ex- 

 periments to determine the increase in concentration, sections of 

 the beet were placed in small vials holding from 8 to 12 c.c. of solu- 

 tions used. Turgidity was restored in five or six hours in sections 

 of beet placed in 2nH and also in «/2 glycerine. 



