OSMOTIC PROPERTIES OF THE CELL. 3$ 



Reinke has ascertained, firstly, that the amount of evaporation 

 from an organised structure depends upon the degree of its 

 saturation ; it is greatest when the body is fully saturated : 

 secondly, that the pressure which is necessary to force water 

 out of an organised body is at its minimum when the body is 

 at its maximum degree of saturation or imbibition. ? 



III. The Osmotic Properties of the Cell. 



It has been already pointed out in the case of Yeast, that 

 the cell is capable of absorbing water containing various sub- 

 stances in solution, and, now that we have learned something 

 as to the structure of the cell, we are in a position to study 

 this process in detail. If a section of a succulent stem, 

 mounted in distilled water, be examined under the microscope, 

 it will be seen that the parenchymatous cells are fully ex- 

 panded, that they evidently contain as much water as they 



FIG. 9 (after de Vries). Young parenchymatous cell from the peduncle of Cepha- 

 laria kucantha : i, Turgid cell ; 2, the same cell in 4 per cent, nitre solution ; 

 3, in 6 per cent, solution; 4, in 10 per cent, solution, shewing complete 

 plasmolysis : h, cell-wall ; p, primordial utricle ; k, nucleus ; c, chlorophyll- 

 corpuscles ; s, cell- sap ; e, nitre solution which has entered the cell. 



possibly can. Cells in this condition are said to be turgid. 

 If now a 4 per cent, solution of nitre be substituted for the 

 distilled water, it will be observed that the cells become 



