24 PASTEUR AND AFTER PASTEUR 



milk ; had isolated this bacterium lactis, had sown 

 it on milk, and seen it act. If we care for that ill- 

 treated phrase, An epoch-making discovery, here is 

 an occasion for its use. It fixes the date of the 

 birth of the New Learning. 



Paris, this memorable year, claimed him back 

 from Lille: he was appointed in charge of the 

 science-teaching of the Ecole Normale, and of its 

 general management ; and a laboratory was assigned 

 to him, but miserably small and ill-furnished a 

 mere garret in the Rue d'Ulm: but he made it 

 serve, and that for work as revolutionary as any 

 ever accomplished in science. He was studying 

 fermentation, off and on, for twenty years or more. 

 How is it possible to describe, in a page or two, 

 the output of these twenty years, the changes 

 which they wrought in the manufacture of wines, 

 vinegars, and beers ? The incessant use of the 

 microscope, the adaptation of processes to the indi- 

 vidual ways of each ferment, the proper sterilisation 

 of apparatus these were the principles of his 

 teaching. In 1868, he taught France how to keep 

 her rough wines from going sour, by warming them, 

 in the vat, at a certain point of fermentation: in 

 1867, he taught the vinegar-makers of Orleans how 

 to speed-up the fermenting vinegar : in 1871, in 

 London, he took by surprise a huge East-End 

 brewery, proving to them, with his microscope, the 



