THE PAGE OF NATURE. 243 



assumes the condition of active vegetative growth. The 

 germs of the mould, which had been incorporated in the 

 material, begin to live and expand, each bearing a dis- 

 tinct plant, giving rise either by gemmation or nuclea- 

 tion to new plants indefinitely, until the entire ferment- 

 ing principle is exhausted. The form which the Torula 

 cervisice^OT yeast-plant assumes is that of a number of 

 small vesicles, containing others still smaller in their in- 

 terior, strung together in a moniliform or necklace man- 

 ner. By the time that five or six vesicles are strung- 

 together, the fermentation is sufficiently advanced, and 

 the manufacturer checks it. The vegetation is then sus- 

 pended, and the groups of vesicles separate into indivi- 

 duals, the mass of which thus constitutes the yeast. The 

 cells of the yeast-plant are globular at first, but they 

 soon change, while the fermenting principle is being used 

 up, into the oval form ; when the sugar is still more ex- 

 hausted, they become linear and filamentous, advancing to 

 the primary stage of mycelium ; until finally when the 

 whole fermenting matter is absorbed and evaporated, they 

 develop into the normal crust and organs of fructifica- 

 tion of the common Penicillium or blue mould. 



In all saccharine fluids undergoing the alcoholic and 

 even the acetous fermentation, these minute torulce or 

 yeast-cells make their appearance ; the azote or nitrogen 

 contained in them exercising what is called a catalytic 

 action, that is combining with the carbon and oxygen in 

 the fluid, and causing thereby the alcohol to be dis- 

 engaged. The question here arises whether the fungus 

 produces the fermentation, or the fermentation the fungus. 

 The following judicious remarks, from the pen of a well- 



