34 



PURE CULTURES OF 



as prepared in lager beer breweries ; * the glass flasks are 

 two-thirds filled with it. The simplest way of effecting 

 sterilisation is by boiling on the sand-bath. When the 

 liquid has commenced to boil briskly, the glass stopper is 

 inserted into the rubber tube and the steam is allowed to 

 escape for a short time through the bent tube ; the flask is 

 then placed on the cork stand and the asbestos plug im- 

 mediately introduced. If desired, the sterilisation can also, 

 of course, be effected by steam. The method of boiling 



FIG. 6. 



FIG. 7. 



described does not always kill all the germs present. If, 

 for instance, samples from a number of flasks which have 

 been thus treated are introduced into a medium especially 

 favourable for the development of bacteria, and if these are 

 then placed in an incubator at 27-30 C., we shall find that 

 living bacteria were present in some of our wort flasks. 

 These are, however, unable to develop in the boiled wort, 

 and as we have to deal with this liquid only, the fact men- 



* If the produce of yeast is wanted for distilleries, wine manufacturing, &c., 

 nutrient liquids suitable for the purpose are of course employed. 



