334 APPENDIX. 



which might have readily become subjects of permanent 

 misinterpretation. In the midst of a most virulently in- 

 fective atmosphere, where, even after some hours' boiling, 

 there was no escape for infusions supplied with air, the 

 expulsion of the air by less than five minutes' boiling in 

 properly shaped retort-flasks, and the proper sealing of 

 the flasks during ebullition, insured the sterility of the 

 infusions. 



The meaning of a former remark regarding the part 

 played by boiling, in establishments devoted to the pre- 

 serving of meats and vegetables, will be now understood. 



The inertness of the germs in liquids deprived of air is 

 not due to a mere svapension oi their powers. The germs 

 are killed by being deprived of oxygen. For when the 

 air which has been removed by the Sprengel pump is, after 

 some time, carefully restored to the infusion, unaccom- 

 panied by germs from without, there is no revival of life. 

 By removing the air we stifle the life which the returning 

 air is incompetent to restore. 



These experiments on the mortality arising from a 

 defect of oxygen are, in a certain sense, complementary to 

 the beautiful results of M. Paul Bert. Applying his 

 method to my infusions, I find them sterilized in oxygen 

 possessing a pressure of ten atmospheres or more. Like 

 higher organisms, our Bacterial germs are poisoned by the 

 excess and asphyxied by the defect of oxygen. 



A few short sections on Bacteria germs as distinguished 

 from Bacteria themselves,' and on the alleged destruction 

 of germs by merely drying them, on hermetic sealing, and 

 on the deportment of hermetically-sealed flasks exposed to 

 the sun of the Alps, are introduced towards the end of 

 the memoir. 



' By the excellent researches of Dallinger and Drysdale it has 

 been proved that the germs of Monads, as compared with the adnlt 

 organisms, possess a power of resistance to heat in the proportion 

 of 11 to 6. 



