546 FRAGMENTS OF SCIENCE. 



years, the beef-tea within the chamber is found in every 

 case as sweet and clear, and as free from bacteria, as it was 

 at the moment when it was first put in. There is abso- 

 lutely no difference between the air within and that with- 

 out save that the one is d listless and the other dust-laden. 

 Clinch the experiment thus: Open the door of your cham- 

 ber and allow the dust to enter it. In three days after- 

 ward you have every vessel within the chamber swarming 

 with bacteria, and in a state of active putrefaction. Here, 

 also, the inference is quite as certain as in the case of the 

 powder sown in your garden. Multiply your proofs by 

 building fifty chambers instead of one, and by employing 

 every imaginable infusion of wild animals and tame; of 

 flesh, fish, fowl, and viscera; of vegetables of the most 

 various kinds. If in all these cases you find the dust 

 infallibly producing its crop of bacteria, while neither the 

 dustless air nor the nutritive infusion, nor both together, 

 are ever able to produce this crop, your conclusion is 

 simply irresistible that the dust of the air contains the 

 germs of the crop which has appeared in your infusions. I 

 repeat there is no inference of experimental science more 

 certain than this one. In the presence of such facts, to 

 use the words of a paper lately published in the " Philoso- 

 phical Transactions/' it would be simply monstrous to 

 affirm that these swarming crops of bacteria are sponta- 

 neously generated. 



Is there then no experimental proof of spontaneous 

 generation? I answer without hesitation, none! But 

 to doubt the experimental proof of a fact, and to deny 

 its possibility, are two different things, though some 

 writers confuse matters by making them synonymous. In 

 fact, this doctrine of spontaneous generation, in one form 

 or another, falls in with the theoretic beliefs of some 

 of the foremost workers of this age; but it is exactly 

 these men who have the penetration to see, and the honesty 

 to expose, the weakness of the evidence adduced in its 

 support. 



And here observe how these discoveries tally with the 

 common practices of life. Heat kills the bacteria, cold 

 numbs them. When my housekeeper has pheasants in 

 charge which she wishes to keep sweet, but which threaten 

 to give way, she partially cooks the birds, kills the infant 



