SPECIAL METHODS 



159 



necessary. Although there are a great number of vessels 

 designed for this purpose, only one will be described. It 

 is obvious from the start that apparatus of this nature 

 must be somewhat complicated. A modification of the 

 Schulze and Schulow methods has been found fairly satis- 

 factory. 



Apparatus: 



One large Woulfe's bottle, about 3-liter capacity, with three openings. 



One large 2- or 3-liter flask, Erlenmeyer form. 



Two U tubes. 



One cylinder constructed as shown in Fig. 13. 



The apparatus is arranged according to Fig. 12. 



Schulow, I., Ber. d. Dent. Bot. Gesell., Bd. 29, p. 504, 1911. 

 Schulze, C., Landw. Jahrb., Bd. 30, p. 327, 1901. 



Fig. 12. Complete apparatus for growing plants free of bacteria. 



All stoppers and connecting tubes should be made of 

 steam-resistant rubber. The U tube A and the long 

 hard-glass tube B, enlarged at one end for sterile cotton 



