SYSTEMATICALLY SELECTED YEASTS. 31 



could obtain a better pitching yeast by propagating not from 

 the cane sugar flasks, but from wort cultures prepared for this 

 purpose. The growth obtained from the wort cultures, after 

 being rejuvenated frequently and at short intervals at the 

 ordinary temperature, gave a pitching yeast which was 

 inferior to that obtained directly from his culture in cane 

 sugar solution, and which was several years old. Preserva- 

 tion of streak cultures in wort gelatine likewise gave no 

 satisfactory result Thus the experience gained up to the 

 present time indicates that the cane sugar solution affords a 

 good medium for the preservation of brewery yeasts at the 

 ordinary room-temperature ; this holds good in all probability 

 to the same extent for the other yeasts which are employed 

 in the fermentation industry. 



My Old Method. 



Having procured our pure culture for future use, we 

 proceed with the preparation of the yeast on a large scale for 

 the brewery. For this purpose the following apparatus is 

 made use of: Four or five Pasteur 

 flasks of about \\ liter capacity, 

 four copper vessels of the form 

 shown in Fig. 5 or 6, each of 10 

 liters capacity. 



The form of the Pasteur flask is 

 represented in Fig. 3, which shows 

 a slight modification consisting of a 

 bulb blown in the bent tube, the 

 object of which is to ensure greater 

 security against infection. Our 

 pure culture is contained in a flask 

 of this form, and of 125 cc. capacity. 



FlG> 3- 

 The form of the larger 



flasks of i J liter capacity, which are next made use of, is the 

 same. The flask stands on a cork base ; the straight tube is 



