Louis Pasteur: His Life and Labours

bsolute independence which exists between the ferment of butyric acid and the others, he found, contrary to the general belief, that the lactic ferment is incap

ometimes even more, form these vibrios. They move by gliding, the body straight, or bending and undulating. They repr

in a lively manner as if to detach itself from the rest. Often, also, the little rod

to be observed is, that they may be sown in a liquid which contains only ammonia and crystallisable substances, together with the fermentable substances, sugar, lactic acid, gum, &c. The butyric fermentation manifest

Pasteur a new and unexpected peculiarity. The vibrios live and multiply without the smallest supply of air or of free oxygen. Not only, indeed, do they live without air, but the air destroys them and arrests the fermentation which they initiate. If a current of pure carbonic acid is made to pass into the liquid where they are multiplying, the

obies for all the other microscopic beings which, like the larger animals, cannot live without free oxygen. 'It matters little,' added Pasteur, 'whether the

n found himself in a position to approach more nearly to the essential nature of these myst

he same order. In fermentation, on the contrary, the ferment, while nourishing itself with fermentable matter, decomposes a quantity great in comparison to its own individual weight. Again, the butyric ferment lives without free oxygen. Is there not, said Pasteur, a

w of placing in parallelism these two curious physiological

able quantity of this gas. All the life of the cells of the ferment which multiplies itself indefinitely appears then to take place apart from free oxygen gas. In certain breweries in England the fermenting vats have sometimes a capacity of several thousands of hectolitres; and the fermentation liberates pure carbonic acid, a gas much heavier than atmospheric air, which rests on the surface of the liquid in the vat in a layer thick enough to protect the liquid underneath from any contact with the external air. All this liquid mass, then, is inclosed between the wooden sides of the vat

but the proportion of the weight of the decomposed sugar to that of the yeast formed is absolutely different in the two cases. While, for example, in the deep vats, a kilogram of ferment sometimes decomposes seventy, eighty, one hundred, or even one hundred and fifty kilograms of sugar, in the shallow troughs one kilogram of the ferment will be found to correspond to only five or six kilograms of decomposed sugar. These proportions between the weight of the sugar which ferments and the weight of the ferment produced, constitute the measure of what one might call the ferment's character-of that character which distinguishes its mode of life from that of

sms,' M. Dumas said one day to M. Pasteur before the Academy of Sciences, 'you have discovered a third kingdom-the kingdom to which those organisms belong which, with all the pre

rruption. One of the most remarkable of his researches is that which relates to the fermentation of the tartrate of lime. The demonstra