i 5 2 THE POPULAR SCIENCE MONTHLY. 



to us the nature, and which assures the extirpation, of a disorder 

 so virulent and so vile, worth the price paid for it ? It is exceed- 

 ingly important that assemblies like the present should see clearly 

 the issues at stake in such questions as this, and that the properly- 

 informed common-sense of the community should temper, if not re- 

 strain, the rashness of those who, meaning to be tender, would vir- 

 tually enact the most hideous cruelty by the imposition of short-sighted 

 restrictions upon physiological investigation. It is a modern instance 

 of zeal for God, but not according to knowledge, and an instructed 

 public opinion must correct its excess. 



And now let us cast a backward glance on the field we have 

 traversed, and try to extract from our labors such further profit as 

 they can yield. For more than two thousand years the attraction of 

 light bodies by amber was 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 discovery 

 grows out of another, and cannot appear without its proper antece- 

 dent. Thus, before fermentation could be understood, the microscope 

 had to be invented and brought to a considerable degree of perfec- 

 tion. 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 question as to the origin of such micro- 

 scopic organisms, and in this connection the memoir of Pasteur, pub- 

 lished in the "Annales de Chimie" for 1862, is epoch-making, proving 

 as it did to all competent minds spontaneous generation to be thus 

 far a chimera. 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 

 w r ine-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 tem- 

 perature of 50 centigrade, he rendered it unalterable, and thus saved 

 his country the loss of millions. He then went on to vinegar vin 

 aiyre, acid wine which he proved to be produced by a fermen- 

 tation set up by a little fungus called Mycoderma aceti. Torida, 

 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 w r ere 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 



