14 MANUAL OF BACTERIOLOGY. 



To prove that boiling had not made the fluid unfit for the 

 growth of organisms, air was subsequently allowed to have 

 access to it without such precautions, when putrefaction took 

 place in the usual manner. 



These principles underlie the methods used daily for the 

 preservation of meat, fruit and vegetables, in the household and 

 in canning factories. 



Although boiling occasionally failed to prevent fermentation, 

 investigators came with practice to have a smaller number of 

 failures. Such failures it was shown were due to the presence 

 of the resistant forms of the organisms called spores previously 

 alluded to which some bacteria assume. The true nature of 

 spores was recognized later by Cohn. Pasteur found that 

 exposure to steam at temperatures sufficiently high above the 

 boiling point would destroy the most resistant microbes and 

 their spores. But even boiling and subsequent protection 

 from the entrance of bacteria sometimes met with failure. 



The controversies over fermentation and putrefaction lasted 

 almost until the present day. They have been productive of 

 numerous benefits to the arts and manufactures. But, what is 

 of more importance to our subject, they led to a vastly better 

 understanding of diseases produced by microorganisms. The 

 study of bacteria has been pursued with such vigor in the 

 last thirty-five years in fact that most of what we know con- 

 cerning the bacteria of disease has been learned during this 

 period, and advances are still constantly being made. 



The discussions concerning fermentation and putrefaction 

 were still going on when Lister made his brilliant deduction 

 that suppuration and septic processes in wounds were a species 

 of fermentation (1867). From this came the antiseptic and 

 aseptic methods of operating and of dressing wounds, which 

 have made possible the wonderful results of modern operative 

 surgery.* 



*See Roswell Park. History of Medicine. 



