CHAPTER VII. 



PATHOGENIC ANAEROBES. 



Anaerobic bacteria may be furnished conditions, which permit of their development, 

 in a variety of ways and a very considerable number of pieces of apparatus have been 

 devised to secure this end. In a general way all of the methods may be grouped under 

 the following heads: 



1. Displacement of air. 



2. Absorption of oxygen. 



3. Exhaustion of air. 



4. Exclusion of air. 



5. Miscellaneous methods, in the presence of reducing substances as litmus, or 

 a strongly aerobic germ, etc. 



The first two methods are the most reliable. In the displacement method, hydro- 

 gen, carbon dioxide or illuminating gas may be used; hydrogen is best. This gas is 

 readily prepared by the action of sulphuric acid (1:8) on zinc. Either a Kipp generator 

 may be used or one of a simpler construction. The gas should be washed, 1st. in lead 

 nitrate to absorb the sulphuretted hydrogen, 2nd. in silver sulphate to absorb any 

 arseniuretted or phosphuretted hydrogen, and 3rd. in potassium hydrate to remove sul- 

 phur and carbon dioxide. 



The cultures are made in media containing glucose (which should preferably be 

 freshly prepared and always boiled immediately before being inoculated), either as test- 

 tube or plate cultures. Novy's anaerobic jars are perhaps the most satisfactory recep- 

 tacles for the cultures. (For careful description of same, see N. 306.) 



In the second method (Buchner's method) an alkaline solution of pyrogallic acid 

 is used to absorb the oxygen. The cultures may be placed in Novy jars or similar re- 

 ceptacles ; for tube cultures a large wide mouthed bottle fitted with a rubber cork does very 

 well. The dry pyrogallic acid is placed in the bottom of the receptacles, about 1 gram 

 to every 100 cc- of air space, the tubes are put in place, then about 10 cc. of a 

 normal sodium hydroxide is added to each gram of pyrogallic acid, and the apparatus 

 immediately and hemetically sealed. 



REFERENCES. A. 206; L- & K. 98; M. & R. 68; M. & W. 117; McF. 153; P. 

 233; S. 78. 



