BACTERIOLOGICAL ANALYSES 377 



teria, of which Plectridium foetidum is a most frequent repre- 

 sentative, see "Blown Evaporated Milk," Chapter XXIII. This type 

 of micro-organisms requires strictly anaerobic cultural conditions. 

 Under limited laboratory facilities the anaerobic conditions are 

 best produced by the use of oxygen-absorbing" chemicals, such as 

 pyrogallol to which potassium hydroxide is added. Use dry 

 commercial pyrogallol and potassium hydroxide sticks, in pro- 

 portion .of 1 gram pyrogallol to .7 gram potassium hydroxide, 

 dissolved in about 2 c.c. of water. 



Place 50 grams of pyrogallol into the bottom part of a large 

 size desiccator. Have the rim of the desiccator and the cor- 

 responding rim of the cover covered with a mixture of half 

 paraffine and half bee's wax. Pour into the pyrogallol in the 

 desiccator 100 c.c. of water and then throw in 35 grams of 

 potassium hydroxide. Quickly insert culture tubes, or plates, 

 and close the desiccator with the cover, turning the cover so as 

 to secure a perfect seal. Apply three permanent screw clamps. 



Anaerobic germs of the type of Plectridium foetidum grow 

 best in freshly sterilized milk. In the case of Plectridium foeti- 

 dum the milk first curdles, then digests, forming a clear yellow 

 liquid. The digestion begins at the surface and proceeds down- 

 ward. These cultures develop a most penetrating foul odor, 

 resembling that of spoiled eggs. 1 



The technique and methods for : determining the bacteri- 

 ological flora with reference to cultural and morphological 

 characteristics of individual species of microbes present, are 

 identical to those used in the bacteriological study of milk and 

 other similar products, and which are fully described in standard 

 manuals on bacteriology. 



1 For further details on the technique of Anaerobic Cultures see Hunziker 

 Review of Existing- Methods for Cultivating Anaerobic Bacteria. Journal of 

 Applied Microscopy and Laboratory Methods, Vol. V, Nos. 3, 4, 5, 6. 



