CHAPTEE VI. 



The Application of the Results of Scientific 

 Research in Practice. 



IT is universally acknowledged that the process of fer- 

 mentation plays a very important part in all branches of 

 the fermentation industries. The better insight which has 

 been gradually gained in this direction has been brought 

 about through the development of the science of the 

 organisms of fermentation. This gradual development may 

 be divided into three great periods. 



The investigations of the first period all relate to the 

 important question, whether living organisms can come into 

 existence by spontaneous generation. The second period is 

 noted for Pasteur's classical researches. In the third period, 

 dating from 1879, and which was founded by Hansen, a 

 reform was for the first time carried out. 



1. The first period (1745 to 1857) gave rise to the theory 

 of sterilisation and its foundation in practice (see 

 page 9). 



Spallanzani's discoveries in connection with spontaneous 

 generation formed not only the starting-point of modern 

 bacteriology (compare p. 10), but they also acquired great 

 importance in practical life. In 1782 Scheele proved that 

 vinegar can be preserved unchanged after it has been heated, 

 and Appert (1810) likewise showed that beer, wine, and other 

 liquids can be preserved by similar treatment. It was further 

 shown that air can be purified by passing it through a 

 strongly-heated tube (Schwann) or through a cotton-wool 



