SPONTANEOUS GENERATION. 395 



served, water will be found quite as effectual as sul- 

 phuric acid. By the aid of an air-pump, in a highly 

 infective atmosphere I have thus drawn air for weeks 

 without intermission, first through bulbs containing 

 water, and afterwards through vessels containing or- 

 ganic 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 substances was avoided. 



The brief paper of Schulze, published in Poggen- 

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

 another short and pregnant communication by 

 Schwann. Redi, 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 de- 

 velopment 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. Throughout this time there appeared no 

 mould, no infusoria, no putrefaction; the flesh re- 

 mained 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 putrefac- 

 tion is due to decompositions of organic matter attend- 

 ant on the multiplication therein of minute organ- 

 isms. These organisms were derived not from the air, 

 but from something contained in the air, which was de- 

 stroyed by i sufficiently high temperature. There never 

 was a more determined opponent of the doctrine of 

 spontaneous generation than Schwann, though a strange 



