74 PURE CULTURES OF 



Into this flask is introduced the yeast from one of the 

 10-liter metal vessels (Fig. 5 or 6), and sterilised water is then 

 added until the flask is about three-quarters filled. Finally, 

 the stopper (Fig. 16) is inserted, the cap a placed over it and 

 bound with wire at d, and the rubber tube closed by means of 

 the pinch-cock. The flask is now ready to be packed, and this 

 must be done in such a manner that, when unpacked, the 

 flask must present a sterile surface ; this can be effected by 

 wrapping the flask in cotton-wool, or other substances, which 

 has been previously heated for a few hours at 150 C. Full 

 and distinct instructions should be sent from the laboratory 

 from which the yeast is forwarded, and the most important 

 directions should be specially emphasised. 



At my request, Mr. Jorgensen kindly tested this method 

 by sending some samples abroad from his laboratory at 

 Copenhagen, and in all cases a favourable result was obtained. 

 A metal flask has, of course, greater strength, but by the 

 employment of such a vessel we lose the special advantages 

 possessed by the glass flask. 



The yeast in such a flask is sufficient to start the 

 fermentation of 50 liters of wort. This can be measured with 

 sufficient accuracy by means of the vertical glass tube f t 

 Figs. 8 and 10. If the temperature of the room in which the 

 fermenting cylinder has been placed is about 8 C., fresh wort 

 may be added after 4 to 5 days until it reaches the highest 

 mark on the glass tube f, but if the development proceeds 

 slowly, more time should be allowed. 



For sending pure cultivated yeast in an absolutely pure 

 condition and in such a manner that its multiplication can be 

 effected easily and with certainty, I have likewise made use of 

 the following method, which has also given good results : To 

 the small cylindrical flasks generally known as Freudenreich 

 flasks, I have added a side-tube (see Fig. 17). The tube a on 

 the hood is, as usual, filled with cotton-wool ; a firm layer of 

 cotton-wool is placed at the bottom e of the flask, and a plug 



