VIII. ERCKMANN-CHATRIAN. By Edmond About, Athenæum,

IX. ON THE SHELF,

THE NIGHT Cometh,
PSALM CXLVIII., .

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From the German of

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From The Fortnightly Review. FERMENTATION, AND ITS BEARINGS ON THE PHENOMENA OF DISEASE.*

ONE of the most remarkable characteristics of the age in which we live, is its desire and tendency to connect itself organically with preceding ages to ascertain how the state of things that now is came to be what it is. And the more earnestly and profoundly this problem is studied, the more clearly comes into view the vast and varied debt which the world of to-day owes to that fore-world, in which man by skill, valor, and well-directed strength first replenished and subdued the earth. Our pre-historic fathers may have been savages, but they were clever and observant ones. They founded agriculture by the discovery and development of seeds whose origin is now unknown.

They tamed and harnessed their animal
antagonists, and sent them down to us as
ministers, instead of rivals in the fight for
life. Later on, when the claims of luxury
added themselves to those of necessity,
we find the same spirit of invention at
work. We have no historic account of the
first brewer, but we glean from history
that his art was practised, and its produce
relished, more than two thousand years
ago. Theophrastus, who was born nearly
four hundred years before Christ, described
beer as the wine of barley.
tremely difficult to preserve beer in a hot
country, still, Egypt was the land in which
it was first brewed, the desire of man to
quench his thirst with this exhilarating
beverage overcoming all the obstacles
which a hot climate threw in the way of its

manufacture.

It is ex

Our remote ancestors had also learned by experience that wine maketh glad the heart of man. Noah, we are informed, planted a vineyard, drank of the wine, and experienced the consequences. But, though wine and beer possess so old a history, a very few years ago no man knew the secret of their formation. Indeed, it might be said that until the present year no thorough and scientific account was ever given of the agencies which come into play in the manufacture of beer, of the

conditions necessary to its health, and of
the maladies and vicissitudes to which it
is subject. Hitherto the art and practice
of the brewer have resembled those of the
physician, both being founded on empir-
ical observation.
By this is meant the
observation of facts apart from the princi-
ples which explain them, and which give
the mind an intelligent mastery over them.
The brewer learnt from long experience
the conditions, not the reasons of success.
But he had to contend, and he has still to
contend, against unexplained perplexities.
Over and over again his care has been
rendered nugatory; his beer has fallen
into acidity or rottenness, and disastrous
losses have been sustained, of which he
It
has been unable to assign the cause.
is the hidden enemies against which the
physician and the brewer have hitherto
contended, that recent researches are
dragging into the light of day, thus pre-
paring the way for their final extermina-
tion.

Let us glance for a moment at the out-
ward and visible signs of fermentation.
A few weeks ago I paid a visit to a private
still in a Swiss chalet; and this is what I
saw. In the peasant's bedroom was a cask
with a very large bunghole carefully closed.
The cask contained cherries which had
lain in it for fourteen days. It was not
entirely filled with the fruit, an air-space
being left above the cherries when they
were put in. I had the bung removed,
and a small lamp dipped into this space.
Its flame was instantly extinguished. The
oxygen of the air had entirely disappeared,
its place being taken by carbonic acid
gas.* I tasted the cherries: they were
very sour, though when put into the cask
The cherries and the
they were sweet.
liquid associated with them were then
placed in a copper boiler, to which a cop-
per head was closely fitted.
head proceeded a copper tube which passed
straight through a vessel of cold water,
and issued at the other side. Under the
open end of the tube was placed a bot-
tle to receive the spirit distilled.
The

From the

The gas which is exhaled from the lungs after the oxygen of the air has done its duty in purifying the A discourse delivered before the Glasgow Science blood, the same also which effervesces from soda water Lectures Association, October 19th, 1876.

and champagne.

flame of small wood-splinters being applied to the boiler, after a time vapor rose into the head, passed through the tube, was condensed by the cold of the water, and fell in a liquid fillet into the bottle. On being tasted, it proved to be that fiery and intoxicating spirit known in commerce as Kirsch or Kirschwasser.

The cherries, it should be remembered, were here left to themselves, no ferment of any kind being added to them. In this respect what has been said of the cherry applies also to the grape. At the vintage the fruit of the vine is placed in proper vessels and abandoned to its own action. It ferments, producing carbonic acid; its sweetness disappears, and at the end of a certain time the unintoxicating grape-juice is converted into intoxicating wine. Here, as in the case of the cherries, the fermentation is spontaneous - in what sense spontaneous will appear more clearly by and-by.

It is needless for me to tell a Glasgow audience that the beer-brewer does not set to work in this way. In the first place the brewer deals not with the juice of fruits, but with the juice of barley. The barley having been steeped for a sufficient time in water, it is drained, and subjected to a temperature sufficient to cause the moist grain to germinate; after which it is completely dried upon a kiln. It then receives the name of malt. The malt is crisp to the teeth, and decidedly sweeter to the taste than the original barley. It is ground, mashed up in warm water, then boiled with hops until all the soluble portions have been extracted; the infusion thus produced being called the wort. This is drawn off, and cooled as rapidly as possible; then, instead of abandoning the infusion, as the wine-maker does, to its own action, the brewer mixes yeast with his wort, and places it in vessels each with only one aperture open to the air. Soon after the addition of the yeast, a brownish froth, which is really new yeast, issues from the aperture, and falls like a cataract into troughs prepared to receive it. This frothing and foaming of the wort is a proof that the fermentation is active.

What is this yeast, and how did the brewer become in the first instance possessed of it? Examine its quantity before and after fermentation. The brewer introduces, say 10 cwts. of yeast; he collects forty, or it may be 50 cwts. The yeast has, therefore, augmented from four to five fold during the fermentation. Shall we conclude that this additional yeast has been spontaneously generated by the wort ? Are we not rather reminded of that seed which fell into good ground, and brought forth fruit, some thirtyfold, some sixtyfold, some an hundredfold? On examination this notion of organic growth turns out to be more than a mere surmise. In the year 1680, when the microscope was still in its infancy, Leeuwenhoek turned the instrument upon this substance, and found it composed of minute globules suspended in a liquid. Thus knowledge rested until 1835, when Cagniard de la Tour in France, and Schwann in Germany, independently, but animated by a common thought, turned microscopes of improved definition and heightened powers upon yeast, and found it budding and sprouting before their eyes. The augmentation of the yeast alluded to above was thus proved to arise from the growth of a minute plant, now called Torula (or Saccharomyces) Cerevisiæ. Spontaneous generation is therefore out of the question. The brewer deliberately sows the yeast-plant, which grows and multiplies in the wort as its proper soil. This discovery marks an epoch in the history of fermentation.

But where did the brewer find his yeast? The reply to this question is similar to that which must be given if it were asked where the brewer found his barley. He has received the seeds of both of them from preceding generations. Could we connect without solution of continuity the present with the past, we should probably be able to trace back the yeast employed by my friend Sir Fowell Buxton to-day, to that employed by some Egyptian brewer two thousand years ago. But you may urge that there must have been a time when the first yeast-cell was generated. Granted exactly as there was a time Whence comes the yeast which issues when the first barleycorn was generated. so copiously from the fermenting-tub? | Let not the delusion lay hold of you, that

a living thing is easily generated, because it | there, but so long as there is no seed sown is small. Both the yeast-plant and the there is no life developed, and no sign of barley-plant lose themselves in the dim that fermentation which is the concomitwilight of antiquity, and in this our day tant of life. Nor need you resort to a there is no more proof of the spontaneous boiled liquid. The grape is sealed by its generation of the one, than there is of the own skin against contamination from withspontaneous generation of the other. out. By an ingenious device Pasteur has I stated a moment ago that the fermen- extracted from the interior of the grape tation of grape-juice was spontaneous; but its pure juice, and proved that in contact I was careful to add, "in what sense with pure air it never acquires the power spontaneous will appear more clearly by- to ferment itself, nor to produce fermentaand-by." Now this is the sense meant. tion in other liquids.* It is not, therefore, The wine-maker does not, like the brew-in the interior of the grape that the origin er and distiller, deliberately introduce of the life observed in the vat is to be either yeast, or any equivalent of yeast, into his vats; he does not consciously sow in them any plant, or the germ of any plant; indeed he has been hitherto in ignorance whether plants or germs of any kind have had anything to do with his operations. Still, when the fermented grape-juice is examined, the living Torula concerned in alcoholic fermentation never fails to make its appearance. How is this? If no living germ has been introduced into the wine-vat, whence comes the life so invariably developed there?

You may be disposed to reply with Turpin and others, that in virtue of its own inherent powers, the grape-juice when brought into contact with the vivifying atmospheric oxygen, runs spontaneously and of its own accord into these low forms of life. I have not the slightest objection to this explanation provided proper evidence can be adduced in support of it. But the evidence adduced in its favor, as far as I am acquainted with it, snaps asunder under the least strain of scientific criticism. It is, as far as I can see, the evidence of men, who, however keen and clever as observers, are not rightly trained experimenters. These alone are aware of the precautions necessary in investigations of this delicate kind. In reference, then, to the life of the wine-vat, what is the decision of experiment when carried out by competent men? Let a quantity of the clear, filtered "must" of the grape be so boiled as to destroy such germs as it may have contracted from the air or otherwise. In contact with germless air the uncontaminated must never ferments. All the materials for spontaneous generation are

sought.

What, then, is its true origin? This is Pasteur's answer, which his well-proved accuracy renders worthy of all confidence. At the time of the vintage microscopic particles are observed adherent, both to the outer surface of the grape and of the twigs which support the grape. Brush these particles into a capsule of pure water. It is rendered turbid by the dust. Examined by a microscope some of these minute particles are seen to present the appear ance of organized cells. Instead of receiving them in water, let them be brushed into the pure inert juice of the grape. Forty-eight hours after this is done, our familiar Torula is observed budding and sprouting, the growth of the plant being accompanied by all the other signs of active fermentation. What is the inference to be drawn from this experiment? Obviously that the particles adherent to the external surface of the grape include the germs of that life which, after they have been sown in the juice, appears in such profusion. Wine is sometimes objected to on the ground that fermentation is "artificial;" but we notice here the responsibility of nature. The ferment of the grape clings like a parasite to the surface of the grape, and the art of the winemaker from time immemorial has consisted in bringing—and it may be added, ignorantly bringing-two things thus closely associated by nature into actual contact with each other. For thousands of years,

The liquids of the healthy animal body are also sealed from external contamination. Pure blood, for

example, drawn with due precautions from the veins, will never ferment or putrefy in contact with pure air.