174 



TECHNOLOGY OF BACTERIA. 



recently heated. The flask is then inverted, and 

 the capillary neck is passed through the opening 

 in the protective cap of a culture-tube. A suf- 

 ficient quantity of fluid is then transferred by the 

 application of gentle heat to the base of the in- 

 verted flask. (See Fig. 2.) Care must be taken 

 not to wet the protective cotton with 

 the culture-fluid ; and immediately 

 after this has been introduced, the ori- 

 fice in the cotton wadding is closed 

 by placing two more layers of the 

 same material over those which had 

 previously been secured to the neck 

 of the bottle or tube. This outer 

 protective layer may be conveniently 

 secured in position by means of a 

 rubber band which admits of its be- 

 ing quickly removed for the purpose 

 of introducing the bacteria which it 

 is proposed to cultivate, or of extracting a drop of 

 fluid for microscopical examination. This is ac- 

 complished by means of a capillary tube which has 

 been sterilized by heat just before it is used, and 

 which is introduced through the small opening in 

 the inner layers of the cotton cap. When tubes 

 or bottles prepared in this way are set aside for a 

 considerable time, or when the free admission of 

 oxygen to the interior is not considered necessary, 

 it is well to cover the cotton cap with a piece of 

 thin sheet-caoutchouc, secured by means of a rub- 

 ber band. This serves to protect the cotton cap 



Fig. 2. 



