[S CULTURE METHODS AND TECHNIQUE 



quantities of media should be sterilized three times. Between the 

 periods of sterilization media should be placed at a temperature 

 favorable for most bacterial development, and not in a cold place, 

 this being in order that any spores might pass into the vegetative 



FIG. 5 a. AUTOCLAVE, ERECT TYPE, CLAMPED Top, HEATED BY GAS 

 (Photograph by Geo. M. Reed) 



state within twenty-four hours, and thus be killed at the next 

 sterilization. 



A suggestion which has been made by Theobald Smith is of 

 interest in connection with the sterilization of media which may con- 

 tain anaerobic bacteria. If such media are sterilized in thin layers, 

 oxygen may have comparatively free access to any submerged 



