AND THE CAUSES OF FERMENTATION. 113 
ignored by M. Pasteur and his followers.* This 
difference is, moreover, thoroughly in accordance 
with the broad physico-chemical theory of fermen- 
tation which has been so ably expounded by Baron 
Liebig and others, and the truth of which may now 
be regarded as definitely established. According to 
this theory ‘living’ matter, as a ferment, would take 
rank merely as a chemical compound having a 
tolerably definite constitution; and this, we might 
-reasonably infer, would, like other chemical com- 
pounds, be endowed with definite properties—and 
amongst others that of being decomposed or radically 
altered by exposure to a certain amount of heat. 
Looked at also from this essentially chemical point of 
* See, for instance, all M. Pasteur’s celebrated experiments in which 
he had recourse to an ‘‘ ensemencement des poussiéres qui existent en 
suspension dans V’air,” as recorded in chaps. iv. and v. of his memoir in 
“ Ann. de Chimie et de Physique,” 1862, M. Pasteur was engaged in 
an investigation one of the avowed objects of which was to determine 
whether fermentation could or could not take place without the intervention 
of living organisms, which M. Pasteur held (in opposition to many other 
chemists) to be the only true ferments, In his inoculating compound 
(dust filtered from the atmosphere), there was, as M. Pasteur was fully 
aware, a large amount of what his scientific opponents considered not- 
living ferment, whilst Zossidly there existed a certain number of living 
ferments. In explaining the results of his experiments, however, M. 
Pasteur and others thought he was pursuing a logical and scientific 
method when he attributed these results to the action of the possibly 
existing element of the inoculating compound, whilst he ignored alto- 
gether the other element which was certainly present in comparatively 
large quantity, and the testing of whose efficacy was the ostensible 
object .of his research. 
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