DISCOVERY OF THE LACTIC ACID BACTERIA. 223 



We may recall to mind that Pasteur, in his treatise (against 

 spontaneous generation) in 1862, pointed to the non-success ex- 

 perienced by the opponents of this theory, especially Schroder and 

 Dusch, when they employed milk for their refuting experiments. 

 Knowing, as we do, that, before Pasteur, no one had succeeded in 

 rendering milk absolutely free from germs, it is therefore easy to 

 understand that up till then nothing definite could be urged 

 against the hypothesis, put forward by chemists, of the purely 

 chemical nature of the process of lactic fermentation. Thus, for 

 example, ROWLANDSON (I.), under the influence of the Liebig and 

 Gay-Lussac theories of fermentation, defined the preliminary con- 

 version of lactose into lactic acid in the souring of milk as an oxida- 

 tion process, and expressed the naive opinion that a cow that had 

 been running about (and therefore breathing rapidly) before milk- 

 ing would yield a milk rich in oxygen, and consequently liable to 

 turn sour with unusual rapidity. The opinion of FREMY and 

 BOUTRON-CHALARD (I.), (formed in 1841, under the influence of 

 Liebig's theory), that casein was the cause (" ferment ") of lactic 

 fermentation, was revived, though with little success, by A. P. 

 FOKKER (I.) in 1889. 



Pasteur (X.) was the first to describe (1857) an organism 

 characteristic of lactic fermentation, and to prove the same capable 

 of producing acidification in a sweet, sterile milk. This organism, 

 which Pasteur named the " ferment, or yeast, of lactic fermenta- 

 tion," was a bacterium. A pure culture of this, in the present 

 meaning of the term, was at that time unattainable, no suitable 

 method having then been devised. Pasteur demonstrated the 

 difference existing between this " ferment " and that of alcoholic 

 fermentation, and proved that in nutrient media containing sugar, 

 the former organism always sets up lactic fermentation, whilst the 

 other invariably gives rise to alcoholic fermentation. 



This discovery formed an important and welcome support to 

 the theory of specific ferments promulgated by Fr. Kiitzing in 

 1837, and implying that chemically different fermentations are 

 carried out by physiologically different species of organisms. 



135. Bacterium lactis Lister, and Bacillus aeidi 

 lactici Hueppe. 



The important work issued in 1873 by the English surgeon and 

 founder of the antiseptic treatment of wounds has already been 

 noticed ( 68). In that paragraph the methods of working em- 

 ployed by him at that time were referred to as defective and 

 misleading. It was also stated that the name, Bacterium lactis, 

 employed by him, was erroneous, the bacterial culture to which it 

 was applied not being a uniform species, but an indefinite (and 

 very probably highly diversified) mixture of different species. 



LISTER (II.) himself very soon recognised the weakness of his 



