DERIVATION OF ORGANIC BEINGS. 5 



organic particles in the air, by drawing it through a small 

 dossil of gun-cotton, which was then dissolved in a mixture 

 of alcohol and ether, and the residuary matters, after wash- 

 ing, examined by the microscope. Some of the particles 

 thus obtained were evidently of an organic nature, as indi- 

 cated by their form and structure. A good many appeared 

 to be minute grains of starch, and were at once dissolved by 

 concentrated sulphuric acid ; but some corresponded with 

 the spores of the mucedinous Fungi in their powers of 

 resistance to that reagent. M. Pasteur then made various 

 experiments to test the possibility of spontaneous genera- 

 tion, of the same general nature as those already noticed. 

 In one of these a fermentible saccharine fluid was placed in 

 a large glass flask, with the neck drawn out into a capillary 

 tube. After prolonged boiling, the flask was allowed to fill 

 itself with air in cooling, the capillary neck through which 

 the air entered being made red hot, and afterwards herme- 

 tically sealed, when refrigeration was complete. No de- 

 velopment of life took place so long as the flask was intact, 

 though kept at a warm temperature for a month or even 

 six weeks ; but when a small plug of gun-cotton was intro- 

 duced charged in the way described with atmospheric 

 d us t though precautions were taken which appeared 

 abundantly sufficient to prevent the entrance of any other 

 extraneous matters, a turbidity soon became apparent in 

 the fluid, which was quite limpid before, and vegetations 

 began to develop themselves in about the same time that 

 they appeared in comparative experiments on liquids freely 

 exposed to the atmosphere, gradually spreading from the 

 vicinity of the ball of cotton through the whole contents of 

 the flask. 



These and other experiments of M. Pasteur's, bearing on 

 the same subject, appear fully to justify his conclusion, 

 that there is nothing in the air, save these dust-like germs, 

 which can be the cause of the development of animal and 



