NUTRIENT MEDIA AND METHODS OF CULTIVATION. 



133 



aldehyde. The test-tubes, dishes, or 'capsules are placed in a cylin- 

 drical glass vessel containing a pledget of cotton-wool moistened with 



FIG. 68. APPAKATUS FOR ANAEROBIC CULTURES. 



(ROSCOE AND LUNT.) 



formic aldehyde. The vessel is fitted with a ground glass stopper 

 and set aside. The growth almost immediately ceases. Any 

 liquefied gelatine is hardened, so that the exact appearances of 

 cultures are obtained in a permanent form. 



