70 PURE CULTURES OF 



The Introduction of the Yeast into the Propagating 

 Apparatus, and its Transport. 



The yeast which is to be employed to produce a normal 

 fermentation of the wort (about 170 liters) contained in the 

 fermenting cylinder, is grown in the four metal vessels 

 (Figs. 5 or 6) previously described. When as much sedi- 

 mentary yeast as possible has been produced in these in the 

 manner described, all the beer is drawn off. From half to 

 two-thirds of a liter of sterilised water is then run into each 

 vessel, and these are then shaken to loosen the yeast. The 

 yeast thus diluted is now transferred to sterilised two-necked 

 glass flasks of a liter capacity. Four of these will rarely be 

 sufficient, and, as a rule, six will be required. Their contents 

 are finally transferred to the fermenting cylinder through 

 the tube/, Figs. 8 and 10, or a, Fig. 13. All these operations 

 must, of course, be conducted in such a manner that the 

 pure culture receives no contamination. 



It is not possible to transfer the yeast direct from the 

 metal vessels if the tube j\ in Figs. 8 and 10, through which 

 it is introduced is in the side of the cylinder. The position 

 of this tube was selected with a view to render it possible to 

 withdraw samples into sterilised flasks so that the culture in 

 the apparatus may be tested with reference to its purity or 

 otherwise whenever it is thought desirable.* 



In order to be able to analyse the yeast and to prepare 

 the pure culture, some special knowledge and great experi- 

 ence are necessary, and this can only be acquired by long- 

 continued work in a properly equipped laboratory. My 

 different treatises on this subject, and especially the present 

 work, will be of assistance. Their object, with reference to 

 the practical man, is to point out to him the importance 

 of the new reform, so that he may be induced to introduce 



* In Bergh and Jorgensen's apparatus (Fig. 13^) the construction is different, 

 and the above does not apply. 



