PREPARATION OF CULTURE MEDIA 29 



erable length of time, they should be sealed either with paraffin 

 or with a rubber cap. They should always be protected from 

 dampness, as mold fungi are apt to alight on the cotton stoppers 

 and send their filaments into the tube. Before inoculation, they 

 should always be carefully examined, and those which show 

 cloudiness or colonies, as well as those which have shrunk from 

 evaporation, should be rejected. 



