176 



METHODS OF USING CULTURE MEDIA 



upset and mixed with the alkali when it is desired to do so. 

 The cover is now clamped in position with 'all joints well 

 vaselined. Then the outlet tube is connected with a suc- 

 tion pump and the air drawn out. Meanwhile the inlet 

 tube has been connected with a hydrogen generator, and 

 after the jar is exhausted hydrogen is allowed to flow in, 

 and this process is repeated until one is satisfied that the 

 air is replaced. The suction exhausts the air from the tubes 

 or plates so that much less time is required to replace the 

 air with hydrogen. Finally, the stop-cock is closed, and the 

 pyrogallol solution is gently shaken down and mixed with 

 the. alkali so that any remaining oxygen will be absorbed. 



Fig. 125. — Novy jars. 



It must be remembered that facultati\'e anaerobes as well 

 as anaerobes will grow under any of the above conditions, 

 so that cultures of organisms so obtained must be further 

 tested aerobically in order to determine to wliich group 

 the organisms belong. 



Reference has been made above to the "inoculation" of 

 culture media, which means introducing into the medium 

 used the desired material in the proper way. For pmall 

 quantities this is mpst conveniently done with platinum 

 "needles," that is, pieces of platinum wire inserted into the 

 ends of glass rods. The " straight" needle is a piece of heavy 

 platinum wire of about 0.022 inch in diameter (Fig. 12()). 

 It is used most frequently to inoculate all forms of solid 



