ROOTS 



61 



Chip away part of the shell from the larger end of the egg, place 

 it in a ■wide-mouthed bottle or a small beaker full of water, as shown 

 in Fig. 24, then very cautiously pierce a hole through the upper end 

 of the eggshell by pushing a knitting-needle or wire down through 

 the glass tube. 



Watch the apparatus for some hours and note any change in the 

 contents of the tube.^ Explain. 



The rise of liquid in the tube is evidently due to water making 

 its way through the thin membrane which lines the eggshell, 

 although this membrane contains no pores visible even un^er the 

 microscope. 



EXPERIMENT XVI 



Result of placing Sugar on a Begonia Leaf. — Place a little pow- 

 dered sugar on the upper surface of a thick begonia leaf under a small 

 bell-glass. Put another por- 

 tion of sugar or a bit of paper 

 alongside the leaf. Watch for 

 several days. Explain results. 

 The upper surface of this leaf 

 contains no pores, even of 

 microscopic size. 



63. Inequality of Os- 

 motic Exchange. — The 

 nature of the two liquids 

 separated by any given 

 membrane determines in 

 which direction thje 

 greater flow shall take 

 place. 



If one of the liquids is 

 pure water and the other 



1 Testing the contents of the beaker with nitrate of silver solution will 

 then show the presence of more common salt than is found in ordinary water. 

 Explain. 



Rg. 24. — Egg on Beaker of Water, 

 to show Osmosis. 



