Water-Content of Plants 



61 



Root-hairs. - - Germinate seeds of radish and barley in a 

 germiriator l (or upon sawdust or moss) and in moist soil. 



B 



FIG. 17. 



Germinator for dry room: aerated chamber (A) ; saucer (B) ; 

 and flower-pot (C). 



Compare under the microscope the length and appearance of the 

 root-hairs, - - the plants from soil being carefully washed and 

 small rootlets mounted for observation. 



1 Germinators of a variety of types are employed in various physio- 

 logical or seed-testing laboratories. In general, any device which secures 

 constant moisture for the germinating seed is satisfactory, but in no case 

 should any materials be employed which encourage the growth of molds 

 or bacteria. Commonly it is sufficient to distribute the seed so that they 

 shall not be in close contact one with another upon the surface of moist 

 sphagnum moss, sawdust, or other moisture-holding materials of this 

 nature into which the roots will readily penetrate. 



The type of vessel employed is of little consequence so long as there is 



