74 FERMENTS AND MICRO-PARASITES. 



vitalistic theory of fermentation, or the improbability of 

 abiogenesis. Thus a possible objection to some of the 

 experiments was that the deficiency of oxygen in the 

 boiled and hermetically sealed vessels hindered the 

 development of organic life; but this objection was 

 already met by the fact that the experiments with air 

 filtered through cotton wool permitted an undiminished 

 supply of oxygen, and that nevertheless the develop- 

 ment of organisms was prevented. It was much more 

 difficult to answer the other objection; it was said that 

 the heating of the fermentescible substances which were 

 employed for the experiments altered them in such a 

 way that so-called chemical ferments which were pre- 

 viously present, and were able to cause their decom- 

 position without the intervention of organisms, were 

 destroyed by the heat, and that it was for this reason 

 that decomposition did not occur. Had the heating 

 not taken place these substances would have undergone 

 fermentation under the influence of those ferments even 

 without the entrance of organisms. The advocates of 

 spontaneous generation also put forward a similar plea, 

 assuming that as the result of the action of the heat an 

 alteration of the material occurred, and that it thus 

 became unsuitable for the generation of cells. These 

 objections gave rise to a large number of new experi- 

 ments with unboiled and quite unaltered organic 

 materials. Van der Broek, Pasteur, Bindfleisch, Lister, 

 and many others, more recently Meissner, Leube, 

 Hauser, Marchand, Cheyne, were able to preserve for 

 years a great variety of fermentescible substances with- 

 out the occurrence of any fermentation or putrefaction 

 if only they were not previously exposed to the danger 

 of contamination by organisms, and were protected 

 from the entrance of new germs and kept in absolutely 

 pure vessels. In this way success was obtained with 

 grape juice, yolk of egg, blood, milk, the most various 

 animal organs, c. These experiments, which we must 

 discuss more fully at a later period, and as compared 

 with which a few experiments in which the attempt to 

 preserve materials by the same method failed have of 



