SPONTANEOUS GENERATION 823 



be the one thing needed to wake up the dormant infusions. 

 We will examine this point immediately. But meanwhile 

 I would remind him that I am working on the exact lines 

 laid down by our most conspicuous heterogenist. He dis- 

 tinctly affirms that the withdrawal of the atmospheric 

 pressure above the infusion favors the production of or- 

 ganisms ; and he accounts for their absence in tins of pre- 

 served meat, fruit, and vegetables, by the hypothesis that 

 fermentation has hegun in such tins, that gases have beeir 

 generated, the pressure of which has stifled the incipient 

 life and stopped its further development.* This is the 

 new theory of preserved meats. Had its author pierced a 

 tin of preserved meat, fruit, or vegetable under water with 

 the view of testing its truth, he would have found it erro- 

 neous. In well-preserved tins he would have found, not 

 an outrush of gas, but an inrush of water. I have noticed 

 this recently in tins which have lain perfectly good for 

 sixty-three years in the Eoyal Institution. Modern tins, 

 subjected to the same test, yielded the same result. From 

 time to time, moreover, during the last two years, I have 

 placed glass tubes, containing clear infusions of turnip, 

 hay, beef, and mutton, in iron bottles, and subjected them 

 to air-pressures varying from ten to twenty-seven atmos- 

 pheres — pressures, it is needless to say, far more than 

 sufficient to tear a preserved meat tin to shreds. After 

 ten days these infusions were taken from their bottles rot- 

 ten with putrefaction and teeming with life. Thus col- 

 lapses a hypothesis which had no rational foundation, and 

 which could never have seen the light had the slightest 

 attempt been made to verify it. 



'Beginnings of Life," voL i. p. 418. 



