SPONTANEOUS GKNELIATION, 569 



the flasks thus supplied with glacier air showed signs of life 

 afterward, while eight out of twenty of the same infusions, 

 supplied with the air of the plains, became crowded with 

 life. He took his flasks into the caves under the Obser- 

 vatory of Paris, and found the still air in these caves 

 devoid of generative power. These and other experiments, 

 carried out with a severity perfectly obvious to the instructed 

 scientific reader, and accompanied by a logic equally 

 severe, restored the conviction that, even in these lower 

 reaches of the scale of being, life does not appear without 

 the operation of antecedent life. 



The main position of Pasteur has been strengthened by 

 practical researches of the most momentous kind. He has 

 applied the knowledge won from his inquiries to the 

 preservation of wine and beer, to the manufacture of 

 vinegar, to the staying of the plague which threatened 

 utter destruction of the silk husbandry of France, and to 

 the examination of other formidable diseases which assail 

 the higher animals, including man. His relation to the 

 improvements which Professor Lister has introduced into 

 surgery, is shown by a letter quoted in his Etudes sur la 

 Biere.* Professor Lister there expressly thanks Pasteur 

 for having given him the only principle which could have 

 conducted the antiseptic system to a successful issue. The 

 strictures regarding defects of reasoning, to which we have 

 been lately accustomed, throw abundant light upon their 

 author, but no shade upon Pasteur. 



Eedi, as we have seen, proved the maggots of putrefying 

 flesh to be derived from the eggs of flies; Schwann proved 

 putrefaction itself to be the concomitant of far lower forms 

 of life than those dealt with by Redi. Our knowledge 

 here, as elsewhere in connection with this subject, has been 

 vastly extended by Professor (John, of Breslau. " No 

 putrefaction, " he says, " can occur in a nitrogenous sub- 

 stance if its bacteria be destroyed and new ones prevented 

 from entering it. Putrefaction begins as soon as bacteria, 

 even in the smallest numbers, are admitted either accident- 

 ally or purposely. It progresses in direct proportion to the 

 multiplication of the bacteria, it is retarded when they 

 exhibit low vitality, and is stopped by all influences which 

 either hinder their development or kill them. All bacte- 



* P. 43. 



