FERMENTATION. 



the sum of human knowledge regarding electricity, and 

 for more than two thousand years fermentation was effected 

 without any knowledge of its cause. In science one dis- 

 covery grows out of another, and cannot appear without 

 its proper antecedent. Thus, before fermentation could 

 be understood, the microscope had to be invented, and 

 brought to a considerable degree of perfection. Note the 

 growth of knowledge. Leeuwenhoek, in 1680, found yeast 

 to be a mass of floating globules, but he had no notion 

 that the globules were alive. This was proved in 1835 by 

 Cagniard de la Tour and Schwann. Then came the ques- 

 tion as to the origin of such microscopic organisms, and in 

 this connection the memoir of Pasteur, published in- the 

 " Annales de Chimie" for 1862, is the inauguration of a 

 new epoch. 



On that investigation all Pasteur's subsequent labors 

 were based. Ravages had over and over again occurred 

 among French wines. There was no guarantee that they 

 would not become acid or bitter, particularly when 

 exported. The commerce in wines was thus restricted, 

 and disastrous losses were often inflicted on the wine- 

 grower. Every one of these diseases was traced to the life 

 of an organism. Pasteur ascertained the temperature 

 which killed these ferments of disease, proving it to be so 

 low as to be perfectly harmless to the wine. By the simple 

 expedient of heating the wine to a temperature of fifty 

 degrees Centigrade, he rendered it inalterable, and thus 

 saved his country the loss of millions. He then went on 

 to vinegar vinaigre, acid wine which he proved to be 

 produced by a fermentation set up by a little fungus called 

 Mycoderma aceti. Torula, in fact, converts the grape 

 juice into alcohol, and Mycoderma aceti converts the 

 alcohol into vinegar. Here also frequent failures occurred, 

 and severe losses were sustained. Through the operation 

 of unknown causes, the vinegar often became unfit for use, 

 sometimes indeed falling into utter putridity. It had been 

 long known that mere exposure to the air was sufficient to 

 destroy it. Pasteur studied all these changes, traced them 

 to their living causes, and showed that the permanent; 

 health of the vinegar was ensured by the destruction of 

 this life. He passed from the diseases of vinegar to the 

 study of a malady which a dozen years ago had all but 

 ruined the silk husbandry of France, This plague, which 



