32 ANATOMY AND PHYSIOLOGY 



8. In this experiment, what part of the root-hair 

 does the egg membrane represent? the solution of 

 salts in the egg? the water in the beaker? 



9. From the above study explain what takes place 

 when a root-hair is in moist soil. What is thus 

 accomplished for the plant? 



10. Define osmosis. 



Experiment n. To demonstrate osmosis in a plant 

 cell: 



11. Mount in water several uninjured root-hairs. 

 Again identify (high power) the lining layer of 

 cytoplasm. Make a drawing of one of the root- 

 hairs about 50 mm. long. Leave room for two 

 other drawings by the side of the first one. Run 

 a drop of a 5 per cent, salt solution under the 

 cover-glass. This solution is more dense than the 

 cell-sap. 



12. Describe the effect of the salt solution on the proto- 

 plast. 



13. Make a drawing by the side of the first one, showing 

 what you observe. What is the process called? 



14. Now thoroughly irrigate the cells with fresh water, 

 and observe and describe the result. Explain as 

 fully as you can. 



15. By the side of your second drawing make a third, 

 showing the cell as it appears after irrigation with 

 fresh water. 



1 6. In a sentence, name, in order, two processes that 

 take place, (a) when a living plant cell is immersed 

 in a solution more dense than the cell-sap; (b) when 

 a plasmolyzed cell is irrigated with tap-water. 



17. What is one function of the salts dissolved in cell- 

 sap? What is one function of the plasma mem- 

 brane? 



