SYSTEMATICALLY SELECTED YEASTS. 39 



and in most cases we must, therefore, be satisfied with the 

 ordinary wort of the brewery. After passing a flame over the 

 surface of the four vessels containing the pure culture, these 

 are shaken up and the contents poured into the above wort 



If it is not desired to add the partly fermented wort, or 

 if the yeast is not to be transferred directly from the labora- 

 tory to the fermenting vessel, but has to be packed up for 

 sending to a distance, it is advisable to let the vessels stand 

 a few days longer in order that the yeast may form a com- 

 pact layer at the bottom. When this is the case the liquid 

 may be drawn off through the tube b, Fig. 5. It is evident 

 that whilst this is being done, the precaution must be taken 

 of sterilising the air which passes in through the bent tube. 



As soon as a vigorous fermentation has set in, and the 

 first signs of a head have appeared, the whole may be added 

 to 3-4 hectoliters of wort. In this manner we pass rapidly 

 from the small scale to the normal scale of the brewery. 

 The same result can also be attained by adding the yeast 

 to a hectoliter of wort contained in a larger vessel, e. g. of 

 a capacity of about 3^ hectoliters, and introducing an equal 

 quantity of wort as soon as fermentation has set in ; when 

 this is well fermenting and a head has formed, another hecto- 

 liter of wort is added. At the commencement the tempera- 

 ture of the wort should be a shade higher than that of the 

 fermenting cellar, and this is especially the case when the 

 vessel is a small one. If it is desired, each fermentation can 

 also be carried to the end in the ordinary manner, and the 

 sedimentary yeast collected at the end of the primary fer- 

 mentation ; this is then weighed and added to a suitable 

 quantity of wort. It should be pointed out that such a pure 

 culture frequently, though by no means always, attenuates 

 somewhat lower in the first fermentations, and the clarification 

 is also less satisfactory at first. Many brewers have been 

 alarmed by this, although without cause. 



Until the introduction of the large pure yeast apparatus 



