26 MAC Leod, The Place of Science in History. 



The last scientist whose works we wish to recall to 

 mind is Louis Pasteur. 



PASTEUR was born at Dole (Franche Comte) on the 

 27th of December, 1822, and died at St. Cloud on the 

 28th of September, 1895. After having completed his 

 studies at the Royal College of Besancon, he obtained in 

 1840 the degree of bachelier es lettres, and two years later 

 that of bachelor of science. He then went to Paris, where 

 he attended the chemistry course of J. B. A. Dumas at 

 the Sorbonne ; he was nominated laboratory assistant by 

 A. J. Balard. He subsequently became professor of 

 chemistry at Strasbourg and Lille and professor at VEcole 

 nor male de Paris. 



At the time when Pasteur commenced his researches 

 no satisfactory explanation of the phenomena of fermenta- 

 tion had been found. By his ingenious experiments 

 Pasteur demonstrated that the chemical transformations 

 which take place in these phenomena are invariably due 

 to the presence and the development of very small 

 organisms called ferments, or, more generally, microbes. 

 If all trace of these organisms was excluded, no chemical 

 transformation took place. Brewer's wort remains un- 

 changed for years when the air to which it is exposed is 

 cleared of these small living beings. Under the same 

 conditions the juice of grapes remains as it is, without 

 producing alcohol, milk does not become sour, and the 

 acetic fermentation which produces vinegar does not 

 take place. In other terms, the chemical phenomena 

 of fermentation are essentially correlated with a vital 

 phenomenon. 



The economic consequences of this discovery are 

 incalculable. It was the starting point of a real revolution 

 in the numerous industries which depend on the 

 phenomena of fermentation : for example, the production 



