LOUIS PASTEUR 263 



processes that take place in the manufacture of 

 wine, the object being to ascertain why certain 

 wines deteriorated and others did not. In due 

 course he discovered that the wines were spoiled 

 by the entrance into them of microorganisms 

 (yeasts, etc.) that produced fermentations of an 

 unsuitable kind accompanied by flavours which 

 did not suit the tastes of the consumers. This 

 discovery of the causes of so-called "diseases of 

 wines" was of far-reaching importance, as it started 

 a line of reasoning in Pasteur's mind which led him 

 to assume that animal diseases might similarly be 

 due to the multiplication of microorganisms in the 

 body. Some years before, microscopic rod-like 

 vegetable organisms, which are known to-day as 

 bacilli, had been found by Davaine multiplying in 

 the blood of cattle suffering from anthrax. Pasteur 

 explained the significance of these anthrax bacilli: 

 he showed that they were the cause of the disease 

 so fatal to sheep and cattle,- also affecting human 

 beings, especially persons dealing with sheeps' wool 

 and the skins and other products of animals which 

 had died from anthrax. Jenner had demonstrated 

 long before that protection is afforded against 

 smallpox an affection which is communicable by 

 inoculation by vaccine obtained from the calf. 

 The vaccine produced a mild disease which after 

 recovery afforded protection. It was assumed that 

 the smallpox virus had become attenuated or 

 lowered in virulence by passage through the body 



