38 CULTURE METHODS AND TECHNIQUE 



In making transfers and in examining any tube culture, it is 

 well to flame the plug lightly before removal, otherwise particles of 

 dust from the surface may fall into the tube and contaminate it. 

 The flaming should be momentary, and if the tube is turned so 

 that the plugged end is distant from the 

 operator, it will be easy to blow out the 

 flame. The cork should be removed slowly 

 so that there may be no rush of air into the 

 tube, thus bringing contaminating dust par- 

 ticles. It is needless to say that wherever 

 possible tubes should be held horizontally, 

 or as nearly so as the contents will permit. 

 Storage of cultures. In general, it is not 

 well to store tube cultures in a damp place. 

 If moisture is constantly in contact with the 

 glass, or extends through the cotton plug, 

 bacteria will readily enter the tubes. Again, 

 under such circumstances fungous spores 

 may also germinate, the mycelium may grow 

 through the plug, and fruit on the lower side ; 

 thus spores will drop into and contaminate 

 the culture. When the plugs become wet 

 during sterilization, particularly those clos- 

 ing flasks of media, the flasks should be 

 re-sterilized after the plugs are dry, or after 

 fresh plugs are inserted. When placed in 

 storage, a paper cone may be placed over a 

 few tubes or a crate, or under some circum- 

 stances, particularly where it is desirable also 

 FIG. 9. CULTURE OF PLEU- to prevent rapid evaporation, one may em- 

 ROTUS OSTREATUS JACQ. ploy the rubber caps which may be obtained 



rom a Tissue Fragment) for ^ purpose< A re f r igerator is desirable 



whenever cultures are to be maintained fresh for a long period. 

 In this case the ice chamber should have no connection with the 

 storage chambers. Small compartment cases, such as sectional 

 bookcases, are very serviceable for storing cultures away from the 

 dust, under laboratory conditions. The culture room (Fig. 14) is 

 cleaner when the cultures are stored elsewhere. 



