66 



PRINCIPLES OF BACTERIOLOGY 



In boiling all the oxygen is driven out. We prepare all our tetanus 

 toxins in this way: Litre flasks are filled to near the neck with bouillon. 

 This is covered with a one-half inch layer of albolene or paraffin. The 



FIG. 50 



Jar for anaerobic cultures. 



bouillon after boiling is quickly cooled by setting the 

 flask containing it in a shallow layer of cool water, 

 so as to lower the temperature of the lower portion 

 of the bouillon to 40 C. or under, while leaving the 

 paraffin on the surface still fluid. While in this con- 

 dition it is inoculated with the tetanus culture. Bits 

 of tissue suspected to contain tetanus bacilli are 

 dropped into smaller flasks filled and prepared in 

 the same way. 



DISPLACEMENT OF AIR. In the more complicated 

 methods the plates or tubes are placed in jars of a 

 type devised by Novy (Fig. 50), in which the oxygen 

 is displaced by a stream of hydrogen developed by 

 the Kipp apparatus, through the action of pure granu- 

 lated zinc and a 25 per cent, solution of pure sul- 

 phuric acid. When all the oxygen has been displaced 

 the jars are sealed by rotating the stopper. 



ABSORPTION OF OXYGEN. In another method the 

 oxygen is extracted by a mixture of pyrogallic acid 

 and caustic potash. To each 100 c.c. of air space in 

 the jar 1 gram of pyrogallic acid and 10 c.c. of 6 

 per cent, solution of potassium hydroxide are added 

 and the jars immediately sealed. A very simple pro- 

 cedure has been described by Wilson. In a large test- 

 tube a small piece of solid caustic potash is placed 

 and over this powdered pyrogallic acid is poured. 

 A smaller culture tube with the desired medium is 

 inoculated. Water is now added to the large test- 

 tube, which works its way slowly through the pyro- 



FlG. 51 



Buchner's anaerobic 

 tube. The fluid consists 

 of pyrogallic acid dis- 

 solved in 10 per cent, 

 soda solution. By Wil- 

 son's method the tubes 

 are charged with pieces 

 of caustic potash cover- 

 ed with pyrogallic acid. 



