A HISTORY OF SCIENCE 



quite overshadowed by the direct benefits of anaesthe- 

 sia, and the long strides that were taken in scientific 

 medicine during the first fifteen years after Morton's 

 discovery were mainly independent of such aid. These 

 steps were taken, indeed, in a field that at first glance 

 might seem to have a very slight connection with medi- 

 cine. Moreover, the chief worker in the field was not 

 himself a physician. He was a chemist, and the work 

 in which he was now engaged was the study of alcohol- 

 ic fermentation in vinous liquors. Yet these studies 

 paved the way for the most important advances that 

 medicine has made in any century towards the plane 

 of true science ; and to this man more than to any other 

 single individual it might almost be said more than 

 to all other individuals was due this wonderful ad- 

 vance. It is almost superfluous to add that the name 

 of this marvellous chemist was Louis Pasteur. 



The studies of fermentation which Pasteur entered 

 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 

 interest 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 particular by the Frenchman Cagniard Latour 

 and the German of cell-theory fame, TheodorSchwann. 

 These men, working independently, had reached the 

 conclusion, about 1837, that the micro-organisms play 



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