SCIENCE AND WAR 219 



that they were less numerous in some parts of the 

 atmosphere than in others. To prove his contention 

 he set out for Arbois with a largo number of glass 

 bulbs each half filled with a putrescible liquid. The 

 necks of the bulbs had been drawn out and hen IK t- 

 ically sealed after the contents had been boiled. In 

 case the necks were broken (to be again sealed im- 

 mediately), the air would rush in, and (if it lu M 

 the requisite micro-organisms) furnish the condi- 

 tions for putrefaction. It was found that in every 

 trial the contents of a certain number of the bulbs 

 always escaped alteration. Twenty were opened in 

 the country near Arbois free from human habita- 

 tions. Eight out of the twenty showed signs of pu- 

 trefaction. Twenty were exposed to the air on the 

 heights of the Jura at an altitude of eight him 

 and fifty meters above sea-level ; the contents of five 

 of these subsequently putrefied. Twenty others were 

 opened near Mont Blanc at an altitude of two thou- 

 sand meters and while a wind was blowing from the 

 Mer de Glace ; in this case the contents of only one 

 of the bulbs became putrefied. 



While his opponents still professed to believe in 

 the creation of organized beings larking parents, 

 Pasteur was under the influence of the theory of 

 "the slow and progressive transformation of one 

 species into another," and was becoming aware of 

 phases of the struggle for existence hitherto shrouded 

 in mystery. He wished he said to push these sti. 

 far enough to prepare the way for a serious in\ 

 gation of the origin of disease. 



He returned to the study of lactic fcrmrnt.! 

 showed that butyric fermentation may be caused by 



