SPECIAL METHODS 



161 



As soon as the young shoots are 5 to 10 cm. long, raise the 

 inner glass tube slightly (Fig. 13, B) and push the cotton 

 firmly around the base of the young shoot. This should 



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A / f B f i C 



Fig. 13. Apparatus for growing seedlings free of bacteria. 



be repeated two or three times until there is a cotton 

 plug of 3 to 5 cm. around the shoot. Now remove the 

 inner cylinder, excess cotton, and glass rods. 



