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. — Apparatus foe Anaeeobic Cultures, 

 (roscoe and lunt.) 



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

 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. 



