THE STORY OF NINETEENTH-CENTURY SCIENCE 



upon in 1854: were aimed at the solution of a contro- 

 versy that had been waging in the scientific world with 

 varying degrees of activity for a quarter of a century. 

 Back in the thirties, in the day of the early enthusiasm over 

 the perfected microscope, there had arisen a new inter- 

 est in the minute forms of life which Leeuwenhoek and 

 some of the other early workers with the lens had first 

 described, and which now were shown to be of almost 

 universal prevalence. These minute organisms had been 

 studied more or less by a host of observers, but in par- 

 ticular by the Frenchman Cagniard Latour and the Ger- 

 man, of cell-theory fame, Theodor Schwann. These 

 men, working independently, had reached the conclu- 

 sion, about 1837, that the micro-organisms play a vastly 

 more important role in the economy of nature than any 

 one previously had supposed. They held, for example, 

 that the minute specks which largely make up the sub- 

 stance of yeast are living vegetable organisms, and that 

 the growth of these organisms is the cause of the im- 

 portant and familiar process of fermentation. They 

 even came to hold, at least tentatively, the opinion that 

 the somewhat similar micro-organisms to be found in all 

 putrefying matter, animal or vegetable, had a causal re- 

 lation to the process of putrefaction. 



This view, particularly as to the nature of putrefac- 

 tion, was expressed even more outspokenly a little later 

 by the French botanist Turpin. Yiews so supported 

 naturally gained a following; it was equally natural 

 that so radical an innovation should be antagonized. In 

 this case it chanced that one of the most dominating 

 scientific minds of the time, that of Liebig, took a firm 

 and aggressive stand against the new doctrine. In 1839 

 he promulgated his famous doctrine of fermentation, in 



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