5. 



(Classroom experiment.) Bore a hole in the more pointed end of an egg, sufficiently 

 large to insert a small glass tube from 6"-8" in length. Insert the tube 

 about one-half inch, and carefully seal it in place by use of sealing wax. 

 Now chip away the shell from a small portion of the other end of the egg, 

 being careful not to break the thin membrane within. To show osmotic 

 action similar to that in Exp. 3 above, place the egg in a small beaker of 

 water in such a position that the exposed membrane will be completely 

 covered. After a few minutes observe any change in level of the liquid 

 within the tube. 



6. In general, when a strong solution is separated from a weaker 

 solution by a permeable membrane, which will pass through more rapidly? 



7. The egg used in Exp. 5 illustrates very well the action of the root- 

 hairs in absorbing soil water and the food material which it contains. 

 The analogy may be made as follows: the shell of the egg — the cell wall 

 of the root-hair; the membrane surrounding the contents of the egg 

 — the outer surface of the protoplasm lying just within the cell wall of 

 the root-hair; the contents of the egg — the protoplasm of the root-hair 

 cell; the water in the bottle — the water covering the particles of soil about 

 the root-hair. 



Draw an outline of an imaginary root-hair about Vi" in diameter and 

 5" long. Draw parts to indicate the position of cell wall, the outer surface 

 of the protoplasm of the cell, and the protoplasmic contents of the root- 

 hair cell. Now draw about the diagram some figures to represent 

 irregular shaped particles of soil in contact with the wall of the root-hair. 

 About these figures representing particles of soil draw the outline of an 

 imaginary film of water. Indicate by small arrows the direction in which 



Fig. 5. Egg fitted to 

 show osmosis. 



the soil water is moving relative to the root-hair. 



23 



