SPONTANEOUS GENERATION. 295 



water will be found quite as effectual as sulphuric acid. 

 By the aid of an air-pump, in a highly infective atmo- 

 sphere I have thus drawn air for weeks without inter- 

 mission, first through bulbs containing water, and 

 afterwards through vessels containing organic infusions, 

 without any appearance of life. The germs were not 

 killed by the water, but they were effectually intercepted, 

 while the objection that the air had been injured by 

 being brought into contact with strongly corrosive sub- 

 stances was avoided. 



The brief paper of Schulze, published in Poggen- 

 dorf's Annalen for 1836, was followed in 1837 by 

 another short and pregnant communication by Schwann. 

 Kedi, as we have seen, traced the maggots of putrefying 

 flesh to the eggs of flies. But he did not and he could 

 not know the meaning of putrefaction itself. He had 

 not the instrumental means to inform him that it also 

 is a phenomenon attendant on the development of life. 

 This was first proved in the paper now alluded to. 

 Schwann placed flesh in a flask filled to one-third of its 

 capacity with water, sterilised the flask by boiling, and 

 then supplied it for months with calcined air. Through- 

 out this time there appeared no mould, no infusoria, 

 no putrefaction ; the flesh remained unaltered, while 

 the liquid continued as clear as it was immediately 

 after boiling. Schwann then varied his experimental 

 argument, with no alteration in the result. His final 

 conclusion was, that putrefaction is due to decompositions 

 of organic matter attendant on the multiplication there- 

 in of minute organisms. These organisms were derived 

 not from the air, but from something contained in the 

 air, which was destroyed by a sufficiently high tempera- 

 ture. There never was a more determined opponent of 

 the doctrine of spontaneous generation than Schwann, 

 though a strange attempt was made a year and a half 



