70 INOCULATION OF CULTURE-MEDIA WITH BACTERIA 



No. II. ; both tubes are again plugged, and tube No. II. is 

 in turn well shaken. The platinum needle is again sterilized, 

 and finally one or two loopfuls from tube No. II. are intro- 

 duced into Tube No. III., and the contents of the latter well 

 stirred. 



The three tubes are kept on a water-bath at a temperature 

 of between 25 and 30 C., so as to keep the mass liquid. 

 Meanwhile three sterilized glass plates are arranged on three 

 cooling-stages, as depicted in Fig. 32. The gelatin from each 



FIG. 32. 



Levelling-tripod with glass cooling-chamber for plates. 



of the tubes I., II., III. is slowly and evenly poured over 

 the surface of the plates, correspondingly designated as No. 

 I., II., III., and allowed to solidify. It is necessary during 

 the pouring and solidification of the gelatin on the plates that 

 they be carefully protected by a cover against the dust and 

 bacteria from without. 



After solidification is perfect the plates are transferred into 

 culture-dishes placed on glass benches (Fig. 17), and properly 

 labelled. 



To harden the gelatin more rapidly, ice or iced water is 

 generally kept in the lower dish of the cooling-stage. To insure 



