YEAST BREWS 85 



the hops various mischievous bacteria would be almost 

 sure to develop in the brew, injuring or perhaps ruining 

 it. The slimy-bread bacterium, for example (see page 93), 

 is liable to grow in these brews, but the hop extract has a 

 decidedly antiseptic power against ?t. 



By a method somewhat similar to the above, breweries 

 and distilleries cultivate yeast ; but in these large estab- 

 lishments, where there is a demand for large quantities of 

 yeast of the highest grade, a care is given to the brewing 

 impossible in the home. The brewer uses a microscope 

 to test his product, and exercises a care in cultivating his 

 yeast which insures its purity. Yeast from such sources 

 is therefore more reliable than any other, and consequently 

 most yeast in use to-day comes from breweries or dis- 

 tilleries, or from institutions where it is grown upon a 

 large scale. Home brewing of yeast is unreliable and 

 unsatisfactory. 



