kv.] SPONTANEOUS GENERATION. *JG3 



may be thoroughly steamed. Now set the flasks aside 

 to cool, and, when their contents arc cold, add to one 

 of the open ones a drop of filtered infusion of hay 

 which has stood for twenty-four hours, and is conse- 

 quently full of the active and excessively minute 

 organisms known as Bacteria. In a couple of days 

 of ordinary warm weather the contents of this flask 

 will be milky from the enormous multiplication of 

 Bacteria. The other flask, open and exj>osed to the 

 air, sooner or later will become milky with Bacteria, 

 and patches of mould may appear in it ; while the 

 liquid in the flask, the neck of which is plugged 

 with cotton- wool, will remain clear for an indefinite 

 time. I have sought in vain for any explanation 

 of these facts, except the obvious one, that the air 

 contains germs competent to give rise to Bacteria, 

 such as those with which the first solution has been 

 knowingly and purposely inoculated, and to the mould- 

 Fangi. And I have not yet been able to meet with 

 any advocate of Abiogenesis who seriously maintains 

 that the atoms of sugar, tartrate of ammonia, yeast-ash, 

 and water, under no influence but that of free access 

 of air and the ordinary temperature, rear range them- 

 selves and gave rise to the protoplasm of Bacterium. 

 But the alternative is to admit that these Bacteria 

 arise from germs in the air ; and if they are thus pro- 

 pagated, the burden of proof that other like forms are 

 generated in a different manner must rest with the as- 

 serter of that proposition. 



To sum irp the effect of this long chain of evi- 

 dence : — 



It is demonstrable that a fluid eminently fit for 

 the development of the lowest forms of life, but which 

 contains neither germs, nor any protein conrpound, 

 gives rise to living things in great abundance if it is 



