ANAEROBES. 



57 



indications of fecal contamination of water. In connection with B. 

 aerogenes capsulatus, there is some question as to whether the extensive 

 oedema produced by it may not usually be from a terminal or cadaveric 

 infection. 



To Cultivate Anaerobes. Probably the apparatus giving the 

 most perfect anaerobic conditions is the Novy jar, in which the air has 

 been replaced by hydrogen. The difficulties attending the method are : 



1. Unless a special ap- 

 paratus (Kipp's) is 

 at hand, there may 

 be difficulty in pre- 

 venting the sul- 

 phuric acid from 

 frothing over when 

 poured on the zinc. 

 It should, at first, 

 be added in small 

 quantities at a time 

 well diluted (i 

 to 6). 



2. Various wash-bottles 

 are required : one 

 containing silver 

 nitrate solution for 

 traces of AsH 3 and 



one with lead acetate for H 2 S and another with pyrogallic 

 acid and caustic soda for any oxygen that may come over. 



3. Mixtures of hydrogen and air explode. Consequently, in 

 determining whether all air has been expelled and in its 

 place an atmosphere of hydrogen exists, it is necessary to 

 see if the escaping gas burns with a blue flame. Unless 

 this is collected in a test-tube and examined, we may 

 have an explosion. 



4. Except in a large laboratory, where the apparatus is set up 

 and ready for use, too much time would be required. 



5. Simpler methods appear to give as good results. 



FIG. 19. Novy jar. 



