1 8 4 



BUTYKIC ACID FERMENTATION. 



until the publication of H. BUCHNER'S (VII.) method in 1888 that 

 it came into general use in Bacteriology. The test-tube contain- 

 ing the inoculated nutrient medium as a roll culture if desired 



is placed in a 

 large test-tube 

 (Fig. 47) about 

 i J inches wide 

 and 10 inches 

 long, at the 

 bottom of 

 which has just 



previously been inserted i gram of dry 

 commercial pyrogallic acid and 10 c.c. 

 of deci-normal caustic potash. The 

 smaller tube rests on a small wire sup- 

 port, in order to prevent it from dip- 

 ping into the liquid. The " Buchner 

 pyrogallol tube" is closed by a well- 

 fitting previously - moistened rubber 

 stopper, and may then be placed 

 in the incubator. When kept at 

 37 C. the absorption of oxygen is 

 complete in twenty-four hours, or in 

 two days at 20 C. To treat plate 

 cultures by this method, the culture 

 is placed over a basin containing a 

 sufficient quantity of the said solution 

 and resting on a flat plate of ground 

 glass, the whole being covered with 

 a well-sitting bell-glass, the edge of 

 which has been rubbed over with 

 vaseline. Another method for the 

 culture of anaerobic organisms consists 

 in expelling the air from the culture 

 vessel by another gas, e.g. carbon 

 dioxide, hydrogen, coal-gas, or nitrogen. 

 Carbon dioxide is frequently recom- 

 mended by the French school, and 

 particularly by Pasteur, but its em- 

 ployment is not without objections, 

 since it is not an inert gas, but is 

 FIG. 4 8.-Fraenker 8 anaerobic tube, absorbed by the medium, which it 

 ciSK^d^iSSdlSaS then renders acid, and hence has the 

 ed colonies appearing as black spots, power of restricting growth. Moreover, 



Somewhat reduced. (After Fraenkel.) r -,. ,-, -, < T-> TT- 



according to the researches 01 1. Jb RANK- 

 LAND (I.), it acts as a fatal poison on many bacteria. Although 

 experience shows that hydrogen gas is not inert, still it may be 

 accepted as the best to use for anaerobic cultures. Ordinary 





