CHAPTER VI. 



THE APPLICATION OF THE RESULTS OF SCIENTIFIC 

 EESEAECH IN PRACTICE. 



rriHE actual fermentation process plays a very important 

 part in all branches of the fermentation industries. The 

 better insight which has been gradually acquired into the 

 process has been rendered possible by the development of the 

 science of the fermentation organisms. This development may 

 be divided into three historic 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 

 especially distinguished by PASTEUR'S classical researches. In 

 the third period, dating from 1879, founded by HANSEN, a 

 practical reform was carried out for the first time. 



1. During the first period (1745 to 1857) the theory of 

 sterilisation and disinfection was established, and its application 

 in practice was assured. 



SPALLANZANI'S discoveries in connection with spontaneous 

 generation formed not only the starting-point of modern 

 bacteriology, but also acquired great importance in practice. 

 In 1782, SCHEELE proved that vinegar may 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 filter (SCHROEDER 

 and DUSCH). From this the conclusion was drawn that water 



