ROOTS 29 | 
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.1 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 under 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 ieaf 
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 the 
greater flow shall take 
place. 
If one of the liquids is Fic. 24. — Egg on Beaker of Water, 
pure water and the other to show Osmosis. 
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. 
