Supplement to "Nature,'' December 23, 1922 



was derived. Pasteur, in view of his experiments on 

 the decomposition of active substances, which gave 

 rise to inactive products, could not accept this idea, 

 and, regarding living beings as the sole source of 

 asymmetric molecules, was strongly inclined to the 

 belief that in the production of the active alcohol a 

 living organism must have intervened. With char- 

 acteristic energy he commenced the study of the 

 lactic and alcoholic fermentations, the results of which 

 (published in 1857 and i860) were of such far-reaching 

 and unexpected importance. The lactic organism — 

 hitherto not only unknown but almost unsuspected — 

 was discovered and shown to be the specific cause of 

 the 1 In inical change of sugar into lactic acid. In the 

 same way he showed that living yeast was the cause of 

 the alcoholic fermentation of sugar, and triumphed over 

 the objections and arguments of Liebig by growing 

 yeast in a synthetic medium, which contained only 

 mineral salts and well-known pure stable organic 

 substances. By this bold stroke Liebig's contention 

 that the ferment was an unstable substance formed by 

 the action of air on plant juices containing sugar was 

 totally overthrown, and with it fell his theory of 

 fermentation, according to which the instability of the 

 ferment was transferred to the molecule of the sugar. 

 Pasteur, who had at once discovered that carbon 

 dioxide and alcohol were not the only products of 

 alcoholic fermentation, but that succinic acid and 

 glycerol were always formed, in addition to the new-born 

 cells of the organism, regarded fermentation as a physio- 

 logical act by which the yeast acquired some material 

 essential for its life from the fermented sugar. No 



fermentation without life was his deliberate conclusion. 

 He was not, however, heedless of the attempts made by 

 Traube and others to attribute fermentation to the 

 presence of ferments in the living cell, and we are told 

 by Roux that he made many vain attempts by grind- 

 ing, freezing, and plasmolysing yeast cells to obtain 

 evidence as to the existence of such a ferment. It 

 is strange to reflect that it was in all probability an 

 unfortunate selection of a yeast unsuitable for the 

 purpose of such experiments that led to these repeated 

 failures, and that but for this he might have anticipated 

 Buchner by a quarter of a century and have advanced 

 one step further towards the elucidation of this com- 

 plex problem. 



Buchner's great discovery (1897) showed that 

 Pasteur had gone too far in his generalisation. The 

 act of fermentation was shown to be a chemical change 

 produced in the presence of a non-living agent, separable 

 from the cell, an agent the complexity of which still 

 awaits complete resolution. It is the production of 

 this essential instrument of change that is a function 

 of the living cell, and the physiological significance of 

 the act of fermentation is, in all probability, not the 

 acquisition of material but of energy. 



It was Pasteur's great achievement in these researches 

 to have cleared the ground for future work. The old 

 indefinite ideas were shown to be wrong and it was 

 definitely proved that each different type of fermenta- 

 tion was due to a specific organism. Here the modern 

 study of fermentation begins, and every worker on this 

 subject must look back with gratitude to Pasteur's 

 researches as the ultimate inspiration of his labours. 





Pasteur and the Fermentation Industries. 



By Prof. A. 



LOUIS PASTEUR, one of the great figures in the 

 scientific world of the nineteenth century — and 

 there were giants in those days — was a man whose 

 studies covered a more extensive range than those of 

 perhaps any other scientific man of his time, while his 

 researches have had a correspondingly far-reaching 

 influence on both pure and applied science. Pre- 

 eminently an academic worker, he was able to apply 

 his discoveries to preventive medicine, surgery, agri- 

 culture, bacteriology, and the fermentation industries. 

 Some of his later work was, indeed, actually taken up 

 with a distinct practical objective. But the success 

 achieved in his researches in applied science must be 

 attributed solely to his profound studies in pure science, 

 without which he would not have been in possession 

 of the means of attacking problems in such a manner 

 as to obtain results of direct benefit to mankind. In 

 this connexion it may be pointed out that one of the 



R. Ling. 



outstanding features of his genius was his remarkable 

 prescience, which enabled him to turn purely academic 

 work to utilitarian ends. As an example of the 

 practical trend of his mind, his remarks in the preface 

 to his celebrated " Etudes sur la biere " (English 

 Translation) may be quoted : 



" I am convinced," he says, " that I have found a 

 precise, practical solution of the arduous problem 

 which I proposed to myself. . . . These new studies 

 are based on the same principles which guided me in 

 my researches on wine, vinegar, and the silk-worm 

 disease — principles, the application of which are 

 practically unlimited. The etiology of contagious 

 diseases may, perhaps, receive from them an un- 

 expected light." 



If we are to understand the causes which led to 

 Pasteur's association with the fermentation industries, 

 we must consider briefly his early work. It is an old 

 tale, yet one worthy of repetition. From the College 



