FERMENTATION. 287 



which ought to contaiii the viscid matter of the silk. 

 Thus smitten, the worm would go automatically 

 through the process of spinning when it had nothing 

 to spin. Pasteur followed this parasitic destroyer from 

 year to year, and led by his singular power of combin- 

 ing facts with the logic of facts, discovered eventually 

 the precise phase in the development of the insect 

 when the disease which assailed it could with certainty 

 be stamped out. Pasteur's devotion to this enquiry 

 cost him dear. He restored to France her silk hus- 

 bandry, rescued thousands of her population from ruin, 

 set the looms of Italy also to work, but emerged from 

 his labours with one of his sides permanently paralysed. 

 His last investigation is embodied in a work entitled 

 * Studies on Beer,' in which he describes a method 

 of rendering beer permanently unchangeable. That 

 method is not so simple as those found effectual with 

 wine and vinegar, but the principles which it involves 

 are sure to receive extensive application at some future 

 day. 



There are other reflections connected with this sub- 

 ject which, even were they now passed over without re- 

 mark, would sooner or later occur to every thoughtful 

 mind in this assembly. I have spoken of the floating 

 dust of the air, of the means of rendering it visible, and 

 of the perfect immunity from putrefaction which ac- 

 companies the contact of germless infusions and mote- 

 less air. Consider the woes which these wafted parti- 

 cles, during historic and pre-historic ages, have inflicted 

 on mankind; consider the loss of life in hospitals from 

 putrefying wounds; consider the loss in places where 

 there are plenty of wounds, but no hospitals, and in the 

 ages before hospitals were anywhere founded; consider 

 the slaughter which has hitherto followed that of the 

 battlefield, when those bacterial destroyers are let loose, 



