Martin : Effect of concentrated solutions 421 



Glycerine, (a) Isotonic concentration, — nj^ glycerine produced 

 incipient to slight plasmolysis in nearly all the cells, nji glyce- 

 rine plasmolyzed all the cells. 



In most of the cells the plasmolysis was slight, the protoplast 

 withdrawing merely at the corners. In others it was stronger, so 

 that the protoplast separated entirely from the end walls and 

 formed ellipsoidal bodies. 



{b) Increase in concentration. — It required gn/20 potassium 

 nitrate to replasmolyze cells which had been in ;//4 glycerine from 

 four to five hours, gn/20 potassium nitrate plasmolyzed only 

 some of the cells which had been in ///3 glycerine from four to 

 five hours. nf2 potassium nitrate was required to replasmolyze 

 all the cells. It required 2nf;^ potassium nitrate to replasmolyze 

 cells which had been in n/^ or 7^/4 glycerine for twenty-four 

 hours. 



[/rea. (^) Isotonic coicentration, — 7// 3 urea plasmolyzed the 

 cells incipiently or slightly. 



7^/2 urea produced a stronger plasmolysis in all the cells. 



{h) Increase in concentration,- — 7//2 potassium nitrate was re- 

 quired to produced plasmolysis in cells which had been in ;//3 

 urea from four to six hours. 



2;//3 potassium nitrate was necessary to replasmolyze cells 

 which had been in /^/2 urea for five hours. 



Most of the threads were too greatly injured to test the concen- 

 tration after twenty-four hours. 



Acetamid. {a) Isotonic concentration, — 2;// 3 acetamid seemed 

 to be the isotonic concentration. The plasmolysis varied from in- 

 cipient to medium strong, and recovery was usually rapid 



nl2 acetamid produced only very slight plasmolysis in some 

 of the cells. 



(3) Increase in concentration. — It required 2///3 potassium ni- 

 trate to replasmolyze cells which had been in 2;//3 acetamid from 

 five to ten minutes. 



/ 



/ 



Acetamid is very injurious in its action on Spirogyra. Many 

 threads showed signs of injur}' in less than two minutes. Only 

 those which seemed healthy and uninjured were considered in the 

 above experiments. 



