14 ANATOMY AND PHYSIOLOGY 



detect. Its two surfaces are called plasma 

 membranes. 



(9) The clear spaces in the cell are vacuoles, 

 filled with cell-sap. 



(10) Make a drawing of a cell at least 10 cm. in 

 longest measure, showing all parts. 



(n) The lining layer may be easily demonstrated 

 as follows: Place a drop of a 5 per cent, 

 solution of common salt (sodium chloride) 

 at one edge of the cover-glass. Be careful 

 that none of the solution runs over onto the 

 cover-glass. By placing a small piece of 

 blotting paper at the opposite edge of the 

 cover-glass, the water will be removed, and 

 the salt solution drawn under the cover- 

 glass, irrigating the specimen. Follow with 

 another drop if necessary. Observation 

 should be continuous while the specimen 

 is being irrigated with the solution. 



(12) Describe the effect of the salt solution on 

 the lining layer. 



(13) Loosening the lining layer, as above, is 

 termed plasmolysis (i.e., loosening the plasm). 

 The cell is said to be plasmolyzed. 



(14) Make a drawing, the same size as the pre- 

 ceding, showing a plasmolyzed cell. 



(15) Before plasmolysis the lining layer was held 

 . close against the cell-wall with a force, 



already detected (e, p. 12), sufficient to 

 cause a rigid condition of the cell called 

 turgor or turgidity. 



(16) Now replace the salt solution with fresh 

 tap- water, by the method described in (n) 



