CULTIVATION OF ANAEROBIC BACTERIA 85 



and lower dishes to absorb what oxygen remains. The Novy 

 jar (Fig. 31) is used instead of a bell-jar, and sealed after 

 the oxygen is displaced by hydrogen gas. 



Wright's Method. Applicable to both fluid and solid 

 media. After the test-tube is inoculated the plug, which 

 must be of absorbent cotton, is cut off flush with the ex- 

 tremity of the tube and pushed inward for a distance of i cm. 

 It is then impregnated with i c.c. of a watery solution of 

 pyrogallic acid and i c.c. of 5 per cent, sodium hydroxid 



Fig. 31. Novy's jars for anaerobic cultures. 



solution. A tightly fitting rubber stopper is inserted, and 

 the tube is then ready for incubation (Fig. 30). 



Park's Method. An Erlenmeyer flask containing the 

 medium to be used is boiled in a water-bath from ten to 

 fifteen minutes to drive off dissolved oxygen, quickly cooled, 

 and inoculated. Hot melted paraffin is then poured into the 

 flask, which forms a layer over the medium, and on congeal- 

 ing, provides an air-tight seal which does not adhere to the 

 glass so closely as to prevent the escape of any gases formed 

 by the bacterial growth. 



REQUIREMENTS FOR A SMALL LABORATORY 

 Incubator, with thermostat and thermometers. 

 Hot-air oven. 



