46 



ESSENTIALS OF BOTANY 



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. 21, then very cautiously pierce a hole through the upper end 

 of the eggshell by pushing a knitting-needle or ___L 



•wire down through the glass tube. --f***"*"^^^*^ 



Watch the apparatus for some hours and note _X..,^^ ^ ,— J 



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 mem- 

 brane which lines the eggshell, although this mem- 

 brane contains no pores visible even under the 

 microscope. 



Fig. 21. Egg on Beaker of Water, 

 to show Osmosis. 



Fig. 22. 



A, a very young root-hair ; B, a 

 much older one (both greatly 

 magnified), e, cells of the epi- 

 dermis of the root; n, nucleus; 

 •s, watery cell-sap; p, thicker 

 protoplasm lining the cell-wall. 



60. Osmosis in Root-Hairs The soil-water (practically 



identical with ordinary spring or well water) is separated 

 from the more or less sugary or mucilaginous sap inside 

 of the rootrhairs only by their delicate cell-walls lined 



