PRODUCED BY ALCOHOLIC FERMENTS. 165 



retain on its surface the miasmata of infectious diseases." 

 The boiled organic substance in the flask came into contact 

 in this experiment not only with a large volume of air, but 

 also with air the composition of which had in no way been 

 altered ; the small particles suspended in it had alone been 

 removed. In their experiments with meat extract and wort 

 they obtained the same results as Schwann ; they did not 

 always succeed, however, in their experiments with milk and 

 some other substances. There was thus still some uncertainty 

 in several points. 



These old experiments relating to spontaneous generation 

 are still of especial interest for the fermentation industry in 

 that they established not only the principle of sterilisation, 

 but they furnished also a model for the necessary apparatus. 

 They also showed that beer wort is sterile after boiling, and 

 that it can be kept in this condition even when air is passed 

 through it, provided that care be taken to free the air from 

 germs. In practice, the purification of the air has been 

 effected partly by Schwann's and partly by Schroder's and 

 Dusch's methods, and the latter especially has received a very 

 wide application. The flasks with bent tubes employed by 

 Schulze, Schwann, Schroder, and Dusch have become models 

 for the different culture flasks which are now employed in 

 bacteriological and zymotechnic laboratories. In most cases 

 these flasks are plugged with Schroder and Dusch's cotton- 

 wool filters. The high degree of perfection which has been 

 attained in the technique of this subject is due, however, more 

 especially to Pasteur and his pupils. The culture flasks of 

 the laboratory have likewise served as models for the larger 

 forms of apparatus which are now employed in many 

 breweries for the pure cultivation of yeast. 



The first indication that some of the alcoholic ferments 

 are to be regarded as the cause of disease, is found in Bail's 

 writings.* Thus in 1857 he expressed the opinion that 



* Th. Bail, " Ueber Ilefe," Flora, 1857, Nos. 27 and 28, p. 438. 



