x.] BIOGENESIS AND ABIOGENESIS. 237 



Thus the evidence, direct and indirect, in favour of 

 Biogenesis for all known forms of life must, I think, be 

 admitted to be of great weight. 



On the other side, the sole assertions worthy of atten- 

 tion are that hermetically sealed fluids, which have been 

 exposed to great and long-continued heat, have some- 

 times exhibited living forms of low organization when 

 they have been opened. 



The first reply that suggests itself is the probability 

 that there must be some error about these experiments, 

 because they are performed on an enormous scale every 

 day with quite contrary results. Meat, fruits, vegetables, 

 the very materials of the most fermentable and putres- 

 cible infusions, are preserved to the extent, I suppose 

 I may say, of thousands of tons every year, by a method 

 which is a mere application of Spallanzani's experiment. 

 The matters to be preserved are well boiled in a tin case 

 provided with a small hole, and this hole is soldered up 

 when all the air in the case has been replaced by steam. 

 By this method they may be kept for years without 

 putrefying, fermenting, or getting mouldy. Now this 

 is not because oxygen is excluded, inasmuch as it is now 

 proved that free oxygen is not necessary for either fer- 

 mentation or putrefaction. It is not because the tins 

 are exhausted of air, for Vibriones and Bacteria live, as 

 Pasteur has shown, without air or free oxygen. It is not 

 because the boiled meats or vegetables are not putres- 

 cible or fermentable, as those who have had the misfor- 

 tune to be in a ship supplied with unskilfully closed tins 

 well know. What is it, therefore, but the exclusion of 

 germs ? I think that Abiogenists are bound to answer 

 this question before they ask us to consider new experi- 

 ments of precisely the same order. 



And in the next place, if the results of the experi- 

 ments I refer to are really trustworthy, it by no means 



