94 



MANUAL OF BACTERIOLOGY. 



FIG. 28. 



let the reservoir fill with hydrogen; then allow its contents 

 to escape. This should be repeated, after which some of 

 the hydrogen may be collected in an inverted test-tube under 

 water. When this sample is ignited, it should burn without 

 any explosion ; otherwise the hydrogen is not yet ready to 

 use. The hydrogen should bubble through the medium five 



minutes or more. 



The inconvenience of 

 sealing the tubes in the 

 flame, as has to be done in 

 Franker s and other meth- 

 ods for cultivation under 

 hydrogen, is obviated in 

 Novy's apparatus. The 

 tubes or plates are placed 

 in jars through which 

 hydrogen may " be con- 

 ducted. The stopper, hav- 

 ing been smeared pre- 

 viously with a soft wax, 

 is sealed by giving it one- 

 fourth of a turn. 

 Novy's Jar for the Cultivation There have been vari- 



of Anaerobes. oug Qther kinds Q appa _ 



ratus, usually complicated and expensive, devised for the 

 growth of plate-cultures under hydrogen. 



Other expedients for the cultivation of anaerobic bacteria are less 

 effective. In cases where a very deep stab-culture is made in gelatin 

 or agar, where the growth appears in the lower part of the tube by 

 preference, it is supposed to be anaerobic. Koch covered part of the 

 surface of a gelatin plate with a bit of sterilized mica or a cover- 

 glass; bacteria which grew beneath this plate were considered to be 

 anaerobic. Another method was to cover the surface of the gelatin in 

 the cultu/e-tube with sterilized oil. W. H. Park has recommended a mix- 

 ture of solid paraffin with 25 to 50 per cent, of fluid paraffin or albolene 

 as a covering for the surface of anaerobic cultures. This mixture has a 



