286 FRAGMENTS OF SCIENCE. 



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 la- 

 bours were based. Eavages had over and over again 

 occurred among French wines. There was no guaran- 

 tee that they would not become acid or bitter, particu- 

 larly 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 ren- 

 dered it inalterable, and thus saved his country the 

 loss of millions. He then went on to vinegar vin 

 aigre, 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 oc- 

 curred and severe losses were sustained. Through the 

 operation of unknown causes, the vinegar often be- 

 came 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 received the 

 name of pebrine, was the product of a parasite which 

 first took possession of the intestinal canal of the silk- 

 worm, spread throughout its body, and filled the sack 



