54 VINOUS FERMENTATION. 



into chains of vesicles, and in this process changes the Glucose of 

 liquid into Gum and Mannite, with the evolution of Carbonic Acid 

 gas. In some seasons Ropiness is very troublesome, and remedies 

 in abundance have been recommended to check it, in accordance 

 with the prevailing belief on the spot, as to its cause. 



Putrid Fermentation, it need hardly be said, is not due to 

 the growth of Fungus Plants, but to the presence of Bacteria, 

 Vibriones, and Infusoria in general, whose germs are also always 

 present in the air, and when deposited, under circumstances favour- 

 able to their growth, develop themselves with great rapidity to the 

 destruction of the liquor. 



M. Pasteur, having proved that the Vinous Fermentation 

 of Saccharine fluids was caused by microscopic plants, growing 

 from germ cells found on the surface of ripe fruit, next endeavoured 

 to account for their presence. Infinitesimal in size as they are, and 

 only perceptible by the aid of the microscope, he concluded that they 

 formed part of the dust wafted about in the air. The germs them- 

 selves, and their mode of growth, he found to resemble the spores 

 and habit of growth of certain funguses of the family group of 

 Dcematiei, which are common on dead wood during the Autumn. 

 Some species of the family, there is reason to believe, produce two 

 forms of germ cells, the one set adapted to aerial growth, and the 

 other capable of living when submerged in fluid, by decomposing 

 the substances with which they come in contact. Thus Alcoholic 

 Fermentation may be briefly defined as " A Chemical Reaction 

 resulting from the decomposition of Glucose by the 

 growth of certain cellular funguses." 



These striking results of M. Pasteur's labours have met with 

 general acceptance, and they have completely changed the theories 

 Fermentation formerly believed in. The study, however, must be 

 carried much further, before the minute and complicated changes, 

 which are ever going on during the decomposition of organic 

 substances — acting and re-acting on each other as they do — can be 

 fully understood. It is happy for mankind that, guided by practical 



