Skip to main content
BREWERY AND MALT-HOUSE
BREWERY AND MALT-HOUSE
CHAS. GEO. MATTHEWS, F.C.S., F.I.C, ETC.,
FRANCIS EDW. LOTT, F.I.C, A.R.S.M., ETC.
Illustrated by Steel Engravings, Woodcuts^ Lithographs, and
X o n t> o n :
BEMROSE & SONS, 23, OLD BAILEY; AND DERBY.
[ALL RIGHTS RESERVED.}
,om. ITams Jjasteur
THIS BOOK IS INSCRIBED BY THE AUTHORS, IN GRATEFUL
APPRECIATION OF THE HIGH SCIENTIFIC AND PRACTICAL VALUE
OF THE WELL-KNOWN RESEARCHES IN CONNECTION WITH
FERMENTATION UNDERTAKEN BY HIM IN YEARS PAST ; AND IN
ADMIRATION OF THE GENIUS DISPLAYED IN THIS AND OTHER
BRANCHES OF SCIENTIFIC INVESTIGATION.
TABLE OF CONTENTS.
THE MECHANICAL ARRANGEMENTS OF THE MICRO-
Compound Microscope. Principal Parts. Eyepiece and Objective.
Coarse and Fine Adjustments. Stage and Stage Movements. Substage.
Diaphragm. Achromatic or Stage Condenser. Mirrors. Draw-tube.
E RRAT A.
Page 52, line 28, for Plate III., Fig. 4, read Plate V., Fig. 5.
,, 62, ,, 9, ,, Chap. X., ... ,, Chap. XL
,, 65, ,, 18, ,, .ooo25 c - c - ... ,, .00025
ALCOHOLIC FERMENTATION - 26
Grouping of Organisms met in the Brewing process. Yeast. Spon-
taneous Fermentation. Physical nature of Yeast. Microscopical identification
of Yeast. Historical Sketch. Sterility of liquids. Chemical nature of
Yeast. Microscopical examination of Brewers' Yeast. Structure and
Life-history of the Yeast cell. Action of Reagents on Yeast. Sporulation
of Yeast. Influences modifying the appearance of Brewers' Yeast.
Behaviour of Yeast during Beer Fermentation.
THE ALCOHOLIC FERMENTS OF THE ENGLISH PROCESS 40
Introductory remarks. Species occurring. Predominating Species in
Brewers' Yeast. Microscopical characteristics of each. Signs of the
degeneration of Yeast traceable by the Microscope. Saccharomyces
Pastorianus. The Caseous Ferments. Saccharomyces Ellipsoideus.
Saccharomyces Minor. Saccharomyces Apiculatus and Exiguus. Myco-
dermi Vini. Mucor Racemosus. Racking Beer deposits.
viii Table of Contents.
RECENT RESEARCHES IN CONNECTION WITH LAGER BEER
YEAST, ETC. 57
Difference between " high " and " low " Yeasts. Sketch of the Lager
Beer process. Views on relation of "low" to "high" Yeast. Early
Methods of Research and Apparatus employed. Further developments.
Hansen's researches. Ascospore formation. Film or Pellicle formation.
Species or Varieties identified. Practical bearing of results. Pure Yeast
culture. Views suggested by Hansen's work. Applicability of Pure Yeast
culture to English process.
THE MOULDS OR MICROSCOPIC FUNGI 80
Position in the Vegetable Kingdom. General occurrence of Moulds.
General Microscopic Examination of mould growths. Details of Structure.
Modes of reproduction. Sporulation. Motile spores. Alternation of
Generation. Behaviour of Moulds under different conditions of nutriment.
Products of Mould growth. Ferment form of Moulds. Industrial applica-
tion of same. Oidium lactis. Chalara Mycoderma. Oidium lupuli.
Oidium vini. Erysiphe Tuckeri. Penicillium glaucum. Aspergillus glaucus.
Aspergillus niger. Mucor racemosus. Mucor mucedo. Dematium pullulans.
Black mould of Hops and Barley. Hop Mildew. Yellow mould of Hops.
Fusarium hordei. Monilia Candida.
THE BACTERIA OR SCHIZOMYCETES 95
Pasteur's researches. Early observations of Bacteria. Historical
Sketch. Ordinary effects of Bacterial growth. Dimensions and Structure.
Mode of Reproduction. Classification, Cohn's, Zopf's. Variation of form,
Involution forms. Closer consideration of Reproduction by Fission.
Spore Formation. Colour-producing Bacteria. Products of Bacterial
decomposition. Effect of substances, etc., on the growth of Bacteria
Plasma, Electricity, Antiseptics. Modes of research. Apparatus. Selection
of Bacteria. Culture media. Plate cultivation. Staining. Relationship
of Bacteria to Moulds and Alcoholic ferments. Bacteria in the air.
Sarcina group form found in English 'beers. Viscous fermentation.
Mycoderma aceti. Bacterium Pasteurianum. Bacterium xylinum. Pas-
teur's lactic ferment. Bacterium lactis. Bacterium termo. Bacterium
butyricum. Bacillus subtilis. Bacillus ulna. Bacillus leptothrix. Spirillum
tenue. Spirillum undula. Antiseptics. Mode of recording observations.
THE FORCING PROCESS - 128
Introductory remarks. The Forcing Tray, Construction and Dimen-
sions. Mode of heating. Gas regulation, Page's Regulator. Forcing
flasks. Beer samples. Necessary precautions for treatment of flasks, etc.
Temperature of tray and period of forcing. Examination of forced beer
samples. Classification as regards keeping properties. Examples corre-
sponding to classification. Other uses of process.
THE ANATOMY OF THE BARLEY CORN - 138
General appearance of corn. Details of External structure. Capil-
larity. Absorption of water by corn. The Outer coat. The Inner coats.
Details of Internal structure. The Endosperm or Starchy portion of corn.
Barley starch. Other starches. The Germinal parts of the corn. Changes
in corn during Germination.
Table of Contents. ix
HOPS, SUGAR AND WATER 147
The Hop cone. Microscopic examination of the " Condition " of
hop or Lupulin. Changes in the Lupulin caused by ageing. Organisms
in Hop Dust. Organisms in Barley Dust and Steep-water. Frets in beer
due to "dry-hopping." Microscopic examination of Brewing Sugars.
Heisch's test for Waters. Examination of water sediment. Bacteriological
examination of water. Development of Organisms in stagnant water.
Filtration of water.
BREWERY VESSELS, ETC., ETC. 156
Germs present in Air according to varying conditions. Miquel's
experiments. Hansen's experiments Organisms in the Air of Breweries.
Necessity for Cleanliness of Floor, Walls, Vessels, etc. Danger from old
wooden vessels. Cleansing media.
GENERAL REMARKS ON THE BREWERY PROCESS- 163
State of Pitching Yeast Presence of Wild Yeasts. Views in con-
nection with the Origin of Yeast. Theoretical considerations. Causes of
Yeast Deterioration. Abnormal Fermentations. Variations in the Com-
position of Worts. Oxygenation. Effects connected with the use of
A. - 170
Microphotography apparatus, method.
Preparing and Mounting objects for the Microscope.
Various Preparations for Cultivation and Preservation of Organisms,
1. Gelatine for Cultivations.
2. Nutrient Solutions, Raulin's fluid, Pasteur's solution.
3. Preservative Solutions for Vegetable tissues.
4. Cement for Mounting.
Reagents or Testing Liquids, Dyes, Solvents, &c.
Storage of Pitching Yeast.
F. - - - 180
Foreign Pressed Yeast.
INDEX - I9 1
DESCRIPTION OF PLATES.
Compound Monocular Microscope (Frontispiece).
PLATE I. (to face page 24).
Comparison of Micrometer lines with Metric and Inch Scales.
PLATE II. (to face page 34).
Fig. i. Development of Yeast.
2. Sporulation of Yeast (after Reess).
PLATE III. (to face page 42).
Fig. i. Burton Yeast.
2. London Yeast.
PLATE IV. (to face page 44).
Fig. i. Deteriorated Yeast.
PLATE V. (to face page 44).
Fig. i. Saccharomyces Pastorianus.
,, 2. Caseous Yeast No. i (left hand).
Ditto No. 2 (right hand).
3. Saccharomyces Ellipsoideus (left hand after Reess).
Ditto ditto (right hand after M. and L.)
4. Saccharomyces Minor.
n 5. Saccharomyces Exiguus (left hand after Reess).
Ditto (right hand after M. and L.)
,, 6. Mycoderma Vini (left hand, Aerobian form).
Ditto (right hand, Submerged form).
xii Description of Plates.
PLATE VI. (to face page 54).
Fig. !. Beer-deposit free from abnormal forms.
2 . Ditto with wild-yeast forms and Bacteria.
PLATE VII. (to face page 58).
Fig. i. Lager beer Yeast (two authorities).
2. Growth of Saccharomyces Cerevisiae I. (after Hansen).
Pellicle at 6 to 15 C.
Ditto 20 to 34 C.
Ditto old culture.
PLATE VIII. (to face page 86).
Fig. i. Oidium Lactis (after Reess and M. and L.)
2. Penicillium Glaucum (after Maddox).
3. Mucor Racemosus.
4. Ditto (submerged).
5. Fusarium Hordei (after Matthews).
a = Crescent-shaped compound Spores. b = Aerial hyphae.
d Ditto germinating. c Sporangia.
PLATE IX. (to face page 100).
Fig. i. Cladothrix Dichotoma (after Zopf).
2. Ditto ditto.
,, 3. Sarcina Litoralis (after Warming).
4. Bacillus Subtilis sporulating.
5. Germinating spores (after Zopf).
6. Crenothrix Kuhniana (after Zopf).
7. Bacterium Termo (after Cohn).
PLATE X. (to face page 112).
Fig. i. Sarcina Maxima (after Lindner).
2. Pediococcus Acidi lactici (after Lindner).
3. Viscous ferment (after Pasteur).
4. Bacterium Aceti (after Pasteur).
5. Lactic ferment (after Pasteur).
6. Bacterium Lactis.
7. Bacterium Butyricum.
Description of Plates. xiii
Fig. 8. Bacillus Subtilis.
9. Bacillus Ulna.
,, 10. Bacillus Leptothrix.
,, ii. Spirillum Tenue.
12. Spirillum Undula.
PLATE XL (to face page 128).
The Forcing Tray in working order (from a photograph).
PLATE XII. (to face page 136).
Forced Beer Sediments.
Fig. i. Normal residue of S. Cerevisiae.
,, 2. Residue with S. Pastorianus.
3- Caseous ferment, No. i.
4. B. Subtilis, etc.
5. Sarcina, etc.
6. swarming with B. Lactis and B. Subtilis.
PLATE XIII. (to face page 140).
Fig. i. Palea, both layers.
2. ,, fibres of outer layer.
3. outer layer.
4. ,, fibres of inner layer.
PLATE XIV. (to face page 142).
Fig. i. Pericarp.
,, 2. Testa.
3. Diagram Section of Barley-corn (after Holzner).
PLATE XV. (to face page 142).
Longitudinal Section of Barley-corn (reduced from Lintner).
PLATE XVI. (to face page 142).
Fig. i. Transverse Section of Barley-corn.
2. Ditto, some days after germination has proceeded
(from a photograph).
x [ v Description of Plates.
PLATE XVII. (to face page 144).
PLATE XVIII. (to face page 150).
PLATE XIX. (to face page 150).
PLATE XX. (to face page 152).
Organisms, etc., in a water.
PLATE XXI. (tofacepage 170).
DESCRIPTION OF WOODCUTS.
Fig. i. Microscope - 2
2. Eyepiece 3
3. Objective 3
4. Diaphragm - 4
5. Stage Condenser 5
6. Bull's Eye Condenser on Stage 6
7. Mirrors of Microscope
8. Lenses - 10
,, 9. Aberration Test 10
10. Lenses in Compound Objective n
ii. Slide and Cover-Glass Case jy
,, 12. Bull's Eye Condenser in use - 19
,, 13. Wash Bottle 21
,, 14. Camera Lucida applied to Microscope 22
,, 15. Drawing Desk - 23
,, 1 6. Large-scale Yeast Diagram 33
,, 17. Saccharomyces Apiculatus 5 1
,, 1 8. Pasteur Flask 65
19. Chamberland Flask - 66
,, 20. Vacuum Flasks 66
,, 21. Assay Flask 67
22. Bottcher Chamber 68
,, 23. Ranvier Chamber 69
,, 24. Page's Gas Regulator - I 3 I
25. Metal H Piece- '3*
,, 26. Forcing Flask
27. Corn-Bristle and Lodicules 139
,, 28. Method of Section of Corn - - 14
29. Aleurone Cells T 43
30. Hop-Gland Capsules - 148
LITERATURE CONSULTED DURING THE
PREPARATION OF THIS WORK.
" How to work with the Microscope." Lionel S. Beale.
11 The Microscope." Dr. Carpenter.
" The Microscope in Theory and Practice." Nageli and
" The Student's Handbook to the Microscope." A Quekett
" Preparing and Mounting Microscopic Objects." Thomas
" Etudes sur le Vin." L. Pasteur.
"Etudes sur la Biere." L. Pasteur; and Translation of same
entitled " Studies on Fermentation." Faulkner and Robb.
" Fermentation." Schiitzenberger.
" Microbes, Ferments, and Moulds." Trouessart.
" Botanische Untersuchungen iiber die Alkoholgahrungspilze."
" Bacteria and Yeast Fungi." Grove.
Cantor Lectures on " Yeast." A. Gordon Salamon.
" Die Spaltpilze." Dr. W. Zopf.
"Lectures on Bacteria." De Bary; translated by Garnsey and
" Practical Bacteriology." Crookshank.
" Fungi." Cooke and Berkeley.
" Microscopic Fungi." M. C. Cooke.
xviii Literature Consulted.
" Elementary Biology." Prof. Huxley and H. N. Martin.
" Nachrichten iiber den Verein Versuchs und Lehranstalt fiir
Brauerei in Berlin. Die Sarcina-Organismen der Gahrungs-
Gewerbe." Dr. Paul Lindner.
" Die Micro-organismen der Gahrungsindustrie." Alfred
Jorgensen ; and Translation of same, by Dr. G. H. Morris.
" Malzbereitung und Bierfabrikation." J. E. Thausing.
" Handbuch der Spiritusfabrikation." Dr. Maercker.
" Lehrbuch der Bierbrauerei." Dr. Carl Lintner.
" Untersuchungen aus der Praxis der Gahrungsindustrie. Emil
" Infusoria." A. Pritchard.
Transactions of The Laboratory Club, Vol. I.
Transactions of The Burtonon-Trent Natural History Society,
REPORTS, JOURNALS, ARTICLES, &c.
Reports of the Carlsberg Laboratory, 1878 to 1888.
Journal of the Royal Microscopical Society, 1887-8.
Journal of the Quekett Microscopical Club.
Journal of the Chemical Society.
Journal of the Society of Chemical Industry, 1882 to 1889.
" Brewing Trade Review," 1887 to 1889.
" Brewer's Journal," 1880 to 1889.
" Brewer's Guardian," 1880 to 1889.
Articles by Dr. Maddox, 1886 to 1889, in Diary for the Brewing
Room, A Boake.
T N these days when there are few Breweries which
* do not possess a Microscope, it would seem desirable
that the instrument should not fall a prey to the casual
or uninstructed observer, but should rather, by the
knowledge and skill of those that use it, be made a
means of controlling the processes of Malting and
Brewing. A Brewer in becoming practically acquainted
with the Microscope as a controlling agent in his
process, raises, to use a figure of speech, a part of
the line of fortification which science provides against
the hurtful or injurious influences declaring themselves,
when Brewing operations are not conducted with the
intelligence and skill that they ever increasingly require.
The production of a special treatise on the microscope
as applied to Brewing, was first contemplated by the
authors during the delivery of a course of lectures on
this subject to some young brewers. As the lectures
were re-delivered to successive groups of students, the
impression already gained, namely, that a real require-
ment existed amongst Brewers for precise and condensed
instruction in the handling of the microscope, became
xx Introductory Preface.
a very strong one indeed, and the present work was
undertaken. As the writing advanced it was deemed
desirable, in order to make the work as complete as
possible, to cover more ground than the occasion at
first seemed to demand. The original lectures, however,
constitute the nucleus of the work.
The chief aim of the authors has been to collect
within a convenient space and without undue elaboration,
matter that appears to them to be of undoubted value
in its application to Brewing and Malting ; and they
believe that a good deal of information has been
incorporated at the same time, that has not hitherto
been adequately dealt with in print. The fact that a
large part of the information is drawn from works of
undisputed excellence is fully recognized by the authors ;
but the works are many as may be judged from the
list of authorities quoted and the expense involved in
their purchase would be very considerable, besides which,
the search amongst authorities for required information
involves the expenditure of no little time and trouble.
With these explanations, and trusting that their efforts
have been attended by a reasonable amount of success,
the authors hopefully tender this treatise to the judgment
of those who are interested in the Industries with which
it seeks to identify itself.
The authors would here express their cordial thanks
to the friends in Burton (especially the members of the
Chemical Club), and elsewhere, who have materially
aided them by useful suggestions, loans of photographs,
Introductory Preface. xxi
assistance in corrections of MS., revision of proofs, etc.
Where such general kindness has been experienced it
seems invidious to make any distinction by name.
The authors also wish to record their thanks to Mr.
J. E. Wright for the great care and attention bestowed
on the drawings bearing his name.
THE MECHANICAL ARRANGEMENTS OF THE MICROSCOPE,
BEFORE proceeding to discuss the various uses to
which the microscope may be applied by the brewer
and maltster, it is essential that a fair understanding of the
mechanical construction of an ordinary instrument should
be arrived at. Knowledge of the optical principles on
which the action of the lenses depends, though a desirable
acquisition, must from our point of view be looked upon as
a matter of separate study ; and it will therefore be neces-
sary to touch only in the briefest manner on a few purely
optical considerations. We will then in this first chapter
give a general, followed by a more special, description of
the parts of what is known as the Compound microscope.*
Referring to Fig. i, the entire frame-work there repre-
sented, to which various movable accessories of the
microscope may be adapted, constitutes the Stand, consisting
of the tube A and the part A' immediately supporting it,
called respectively the Body and the Limb ; the Stage or
object carrier B, and the Foot C, this last carrying the
whole weight of the instrument, and being, when well con-
trived, adjusted so as to secure a maximum of steadiness.
* A single magnifying lens or Simple microscope is of no special use in connection with
brewing matters, being used chiefly for the examination and dissection of comparatively
large objects under a low magnifying power.
2 The Mechanical Arrangements of the Microscope.
A microscope having a single tube is known as a Mono-
cular one with a double tube as a Binocular microscope.
Into the tube at the upper end (Fig. i a) slides the Eye-
piece (Fig, 2), generally consisting of two lenses with a
diaphragm or stop between them. The lens nearest the
eye of the observer is called the eye-lens, the other the
field-lens, whilst the screw-threaded socket at the other
end of the tube (Fig. i b) carries the Object glass or
Objective (Fig. 3), the most important of the optical parts
of the instrument. The screw-thread as a rule is of such
a diameter as to admit of objectives by different makers
being used with the same tube and stand.*
The body of the microscope is usually controlled by two
movements termed Adjustments. Firstly, the larger milled-
headed screws (Fig. i D) causing the tube by a rack and
* That is to say, a standard has been agreed upon so as to render objectives of
different microscopes interchangeable, but the makers do not seem to exactly work
up to it.
The Mechanical Arrangements of the Microscope. 3
pinion to slide through a vertical distance of some two to
four inches. Secondly, the smaller milled-headed screw (E)
acting either on the whole tube, or on a socket at its lower
end, this last having sometimes an extra play of about three-
sixteenths of an inch upon a spring independent of either
of the adjustments ; this is to protect the objective if it
should be impelled by accident against a glass slide or other
rigid body, such as the stage itself. The movements being
imparted by a fine-threaded screw, may be made as small as
desired : the arrangement is used for focussing with high
powers, and is known as the Fine adjustment, the one first
mentioned being termed, in contradistinction, the Coarse
The plane surface with a central opening or Stage for
carrying slides may be either of metal or glass, with clips, or
a ledge to retain the glass slide. It may be provided with
Movements, which are ordinarily rectangular; that is, by the
use of milled-headed screws (Fig. i G) attached to the
stage, the slide may be caused to move in directions ap-
proaching to or receding from the observer, or from side to
side, the two sets of directions being at right angles to each
other ; or the movements may be compounded into diagonal
directions by using both milled-heads simultaneously. A
circular movement of the Stage is sometimes provided, but
it is not essential to an instrument designed for Brewery
4 The Mechanical Arrangements of the Microscope.
purposes ; neither, indeed, are the rectangular movements,
but they are a great convenience, and are regretfully dis-
pensed with by anyone accustomed to their use. Any
receptacle for accessories immediately underlying the Stage
is called the Sub-stage (Fig. i e). Here, a diaphragm
(Fig. 4 aaa), an arrangement to regulate the passage of
light to the object under examination is usually found, and
is practically indispensable for good definition with high
magnifying powers. It consists, generally, of a perforated
circular plate, rotating on a centre pin as sketched, the
apertures being circles of different diameters ; though for
illumination of special objects, other shaped openings are
sometimes included. A very elegant form is Collins'
" Iris " or graduating diaphragm, in which the aperture
may be regulated by a screw, from the smallest circle to
a considerable opening. Small perforated discs or " Stops"
of different apertures are occasionally made to fix under-
neath the object instead of the movable diaphragm.
To secure the best defining power of the lenses, espe-
cially with high powers, a piece of apparatus called a Stage
Condenser (Fig. 5) which is as a rule, Achromatic is very
useful. It fits into the Sub-stage, and consists of an
The Mechanical Arrangements of the Microscope. 5
arrangement of lenses contrived to concentrate light on the
object under observation. Where this adjunct is employed,
the diaphragm is often placed underneath it as in the
figure: it then exercises a first control on the amount of
light passing to the object.
Another accessory of the Sub-stage is the Nicol's prism,
which constitutes part of the Polarizing apparatus ; a second
Nicol's prism the Analyser fitting into the tube of the
microscope just above the Objective. These accessories
are by no means necessary in a Brewery microscope, but
might be of some use for special work.
An indispensable adjunct to the microscope stand is the
apparatus for reflecting light on to transparent objects
placed on the Stage : for this purpose a double mirror,
on a jointed arm, is usually provided, occupying the posi-
tion indicated by H Fig. i, having one surface plane and the
other concave, the action of which reflectors respectively
will be explained later.
In the case of Binocular microscopes, two images are
6 The Mechanical Arrangements of the Microscope.
obtained by a portion of the rays of light from the Objec-
tive being diverted by a small prism into the second tube
of the instrument, which is usually joined at an angle to
what may be called the main tube. An image is thus
provided for each eye, and the two eye-pieces are moved
simultaneously by a rack and pinion like the coarse adjust-
With a microscope such as that outlined in Fig. i, the
tube can be lengthened by a sliding piece called the Draw
tube, the junction being at d : the object of this is to
increase the amplification, the effect being similar to that
obtained by using a higher power eye-piece.
Amongst necessary appliances is the Bull's-eye con-
denser, which may be on a separate stand as in Fig 1 2 A,
but is more convenient when it can be attached to the
Stage (Fig. 6), and should be provided with a universal
movement as indicated. Its use is to concentrate the light
on to an opaque or semi-opaque object.
In absence of sunlight it is desirable to have a good
source of artificial light to fall back upon ; any of the
following may serve: Firstly, an Argand gas burner
The Mechanical Arrangements of the Microscope. 7
on a vertical stand, which is the more convenient if
it has a telescopic slide for raising or lowering the
burner, and a blue or neutral tint glass cylinder is to
be preferred to the ordinary white glass. Secondly, a
Paraffin lamp, with blue or neutral tint glass chimney, or a
copper chimney is sometimes employed, having an eye or
aperture | to i inch wide, of tinted glass ; or a cylindrical
porcelain shade may surround the glass chimney, having a
portion cut out to let a certain amount of light issue from
the lamp. Amongst more expensive illuminating apparatus,
an incandescent electric lamp fitted on a movable arm, is
a very neat and effective source of light, and has much to
recommend it where the microscope is used intermittently.
The new incandescent gas burners of the Clamond and
Welsbach pattern yield a very nice steady light.
As regards smaller apparatus. For drawing or sketching
with the microscope a Camera Lucida, or Beale's neutral
tint reflector, is often employed attached to the eye-piece ;
of the two forms the reflector is by far the cheaper, and acts
almost as well as the Camera Lucida, which last includes a
small glass prism in its structure. The mode of employ-
ment of these appliances is described under " Manipulation."
Forceps or pincers contrived to fix on the Stage are
sometimes useful for holding an object which it is not con-
venient to put on a glass slide. A dozen or two of glass
slips of the ordinary size, 3 in. by i in., and \ oz. of cover
glasses from f to | in. diameter, may be provided. Cir-
cular cover glasses are more conveniently cleansed than
squares, as they do not break so easily. With combina-
tions not exceeding 300 to 400 diameters, a cover glass of
some strength may be employed, as very fragile ones
provide a constant source of annoyance by breakage.
There are, of course, innumerable accessories for special
kinds of investigation, but the microscope as used by the
brewer does not require them. A convenient Stand, with
8 The Mechanical Arrangements of the Microscope.
one good eye-piece and two objectives of low and high
power respectively, Stage rectangular movements, an
Achromatic condenser, a Bull's-eye condenser, and a good
artificial source of light (should this be required), consti-
tute pretty well the whole of the apparatus necessary or
We will now enter into some further detail in elucidation
of the action of some of the parts of the instrument already
referred to, and thus pave the way to manipulation pure and
simple. The Mirrors, or reflecting apparatus, call for early
consideration, and in connection with Brewing matters the
Concave or hollowed mirror is of the greater importance ;
this form of reflector concentrates the light to a certain
point or " focus " some two or three inches from the centre
of the mirror, as shown in Fig. 7 A, and is used in con-
junction with high power objectives. The best position
of. the mirror may be determined, experimentally, by putting
The Mechanical Arrangements of the Microscope. 9
a flat piece of -oiled tissue paper or tracing paper on the
stage, and moving the mirror vertically till a small disc
or spot of light is shown. The action of the Plane or
flat mirror is shown in the small sketch B, appended to
Fig. 7. Here the light, instead of being concentrated,
is reflected in parallel rays, and consequently with small
objects and object-glasses, a large portion does not impinge
upon them at all. The illumination is, however, quite
adequate and satisfactory for objects viewed under low
powers of magnification.
We may now deal with the lenses of the microscope
as included in the Eyepiece and Objective. Their action
is dependent on the optical principle known as Refraction,
or the bending that rays of light undergo when entering a
medium of different density, a certain amount of the light
being at the same time absorbed or lost. The degree of
refraction is determined by the curvature of the lens and
density of glass, high magnifying power being concurrent
with great curvature, high refraction, and short focal length
or Working Distance ; this last being the interval between
the front lens of an objective and the object examined,
when the latter is in proper focus. With high power
objectives the object must be very close to the lens, and at
a proportionately greater distance as the magnification
Fig. 8 a, b, c shows sections of the Lenses employed in
the construction of the microscope, viz., double-convex,
plano-convex, and plano-concave, the last-mentioned being
used to modify the course of the rays passing through con-
vex lenses to obviate certain imperfections, the nature of
which should be understood so as to aid in their detection.
One of these imperfections is called Spherical Aberration,
and it is rendered obvious by viewing through the micro-
scope a glass slide on which a fine network of squares is
ruled. Fig. 9 B represents what is seen with a proper
io The Mechanical Arrangements of the Microscope.
performance of the properly corrected instrument, whilst
the distorted appearance of A and C indicate opposite
kinds of aberration, caused by lenses imperfectly corrected.
The greater the distortion, the more faulty of course are
the lenses. Eye-pieces and objectives thoroughly corrected
and free from Spherical aberration are said to be Aplanatic.
Another imperfection of the lenses is that termed
Chromatic aberration. It is the cause of the tinting of
colourless objects, and of the coloured fringes so frequently
seen surrounding objects viewed through imperfect instru-
ments. Lenses free from this defect are said to be
The Chromatic and Spherical aberration of a lens may
The Mechanical Arrangements of the Microscope. 1 1
be diminished by reducing the aperture with a stop or
diaphragm, so that only its central portion is employed,
but complete correction is only secured by utilizing different
shaped lenses, as already indicated, and lenses of different
kinds of glass. Objectives of the cheaper kind and espe-
cially those of foreign manufacture, have often only a front
lens, but the majority of good objectives are built up in the
compound form, each lens consisting of two kinds of glass
of different optical properties, cemented together with a
transparent medium such as Canada Balsam ; and the
parting or cracking of the said medium may render an
objective practically useless until re-cemented. Fig. 10
shows the arrangement of three pairs of lenses, i, 2, 3 ;
each pair formed of a double convex of crown glass, and
a plano-convex of flint glass.
A considerable variety of magnifying power may be
obtained by altering the position of lenses in respect to
each other and to the object,
as shown in the employment
of the draw tube ; amplification
may be obtained in this way
or by using higher power eye-
pieces, but in the latter case
often at the expense of good
definition ; for defects of the
object glass which are not
perceptible when the image it
forms is but moderately en-
larged, are brought into pro-
minence when the imperfect
image is magnified or amplified to a much greater extent ;
so that in practice it is found better to vary the power by
employing objectives of different magnification.
Eye-pieces are made of various magnifying powers, but
always comparatively low ones ; the range is generally indi-
i 2 The Mechanical Arrangements of the Microscope.
cated by letters A, B, C, etc., or by numerals, i, 2, 3, etc.,
the power increasing from A and i respectively.
Object glasses or Objectives are usually designated by
their focal distance from the object, viz., i in., in., \ in.,
and so on, but in nearly all cases the distance at which they
focus is less than that implied by the figures, which conse-
quently give an imperfect idea of the real magnifying power.
Generally speaking, objectives range from 4 in., giving
with an A eye-piece some 10 diameters' magnification,
to TfV in. giving 3,000 diameters ; but for Brewers' purposes
two objectives, a i^ in. or i in. giving 30 to 50 diameters,
and a i or i in. yielding 300 to 400 diameters according
to the particular maker suffice. With these objectives,
one good eye-piece a little stronger than an ordinary A,
should be provided ; or if expense is not so much an
object, both A and B eye-pieces may be included. Many
opticians now provide tables in their catalogues giving the
magnifying power of the combinations.
We may here remark that a really good combination
giving only 200 diameters of magnification, will show Yeast
and Bacteria with considerable distinctness of detail as
regards the former, and of size and shape as regards the
latter ; and it is far preferable to work with excellent lenses
magnifying some 200 diameters, than with a poor combina-
tion magnifying double as much, for the latter case means
constant annoyance and irritation from the imperfect per-
The amount of light admitted by an Object glass is of
considerable importance, and depends in great measure on
what is called the Angle of Aperture, which is the angle
formed by two lines from opposite sides of the aperture
of the Objective with its focus. (See Fig. 10 a, b, c.)
Glasses with a high angle of aperture admit much light,
but focussing so close to the object they entail considerable
inconvenience in general work ; those of medium angle
The Mechanical Arrangements of the Microscope. 13
are preferable, combining as they should, Power of Pene-
tration and Brightness of Field. The latter term speaks
for itself ; by the former, is meant the capability of the glass
to give a correct view of an object possessing an appre-
ciable depth. Power of penetration should not be con-
founded with Resolving power, which is the capability of
resolving or dividing the component parts of a minute
object, such as the markings on Diatoms, or the closely-
ruled lines of a test plate : this resolving power is depen-
dent also on angle of aperture, the higher-angled apertures
having a greater resolving power. It will thus be seen
that this quality is opposed to that of penetration, which is
possessed by glasses of low or moderate aperture, and that
the two requisites can only be combined in the same objec-
tive by some sacrifice of each. The purpose for which the
instrument is required must govern the choice of "powers."
Another desideratum in an objective is Flatness of Field,
which means that the whole of a large flat object should
be in correct focus at once, even to the extreme margin of
the field of view ; and the same correctness of focus should
be exhibited by objects lying in the same plane. This
quality is of the most importance in the lower powers
with which large objects are usually examined ; in the
case of glasses of short focus, as a \ in. or higher power,
the object is usually a minute one, and generally placed in
the centre of the field ; and if in the margin of it, the slight
alteration of focus necessary, causes little trouble.
The varying refraction of the thin glass, covering an
object, renders an adjustment of the higher power objec-
tives necessary, and especially so in glasses of high angle
of aperture ; it is usually effected by altering the distance
between the front and second pair of glasses. An engraved
line on the brass mount shows the point to which the lens
should be set for uncovered objects. Its adjustment for
covered objects is effected in the following manner:
14 The Mechanical Arrangements of the Microscope.
Arrange the objective as if for an uncovered object. Focus
any covered object by moving the tube of the microscope ;
next move the milled adjustment ring of the objective till
particles of dust on the upper surface of the cover-glass are
brought into focus. The objective is now corrected for
the thickness of the cover-glass, and it only remains to
re-focus the object with the tube adjustments.
Many of the high power objectives now in use are
worked on the immersion system, which consists in the
interposition of a drop of water or oil generally Cedar
oil between the front lens of the objective, and either the
object itself or its cover-glass. It is of course, requisite
that the objective should be specially corrected for such
use. The advantages gained are a considerable increase
of working distance and penetration.
We will conclude this chapter with a few words on the
choice of a microscope, first summarizing the qualities of a
really good instrument. They are :
A fairly large and well-illuminated field of view.
Freedom from Chromatic and Spherical aberration.
Good definition and penetration.
Flatness of field.
Unless the Brewer has had some experience, it is better,
in purchasing a microscope, to secure the good offices of
someone who knows what a Brewery microscope should be
capable of doing, and what is really good value for the
amount of money it is purposed to expend ; for with the
best intentions on the part of the maker, his want of appre-
ciation of the special purpose to which the instrument is to
be applied, may cause him to forward a disappointing or
There are, at the present time, so many makers of ex-
cellent microscopes at a moderate price, such as Messrs.
Baker, Beck, Browning, Crouch, Steward, Swift, and Wat-
son ; and amongst foreign makers, MM. Seibert and Zeiss
The Mechanical Arrangements of the Microscope. 15
that it would be invidious to make any special selection
for recommendation ; suffice it to say that the authors have
made the chief part of their observations with the more
complete form of Swift's College microscope, than which,
at the price, no more satisfactory instrument has ever been
in their hands. With Messrs. Swift & Son's permission,
a drawing of this microscope is given as the frontispiece.
IN the first place it is obviously of necessity that the
lenses of the microscope should be scrupulously clean.
This is best secured by carefully wiping them with a
cleansed and softened wash-leather, glass-cloth, or silk
handkerchief; some soft fabric that does not " lint " is
essential. Specks of dust on the glasses of the eye-piece
may be detected by turning it round whilst looking through
the instrument, as any such specks will be found to move
with the eye-piece. In cleaning objectives great care must
be exercised, and it is seldom necessary to interfere with
their inner glasses.
The same attention should be occasionally bestowed on
the Stand, and where the microscope is in frequent use, it
may conveniently be kept under a Bell-glass, or glass shade,
with chenille edging to exclude dust, in which case there is
no objection to the powers remaining attached. The
instrument must not stand in a damp place, and on
no account let any liquid accidentally taken up by the
objective, remain and dry upon it. Especial caution must
be exercised in this respect with reagents used in the ex-
amination of an object. Ordinary care should obviate any
contact at all between the objective and substances under
On Manipulation. 1 7
examination. Oil or water immersion lenses should be
cleaned after use.*
Glass slips and cover-glasses after use, if not immediately
cleaned and dried, may be placed in separate vessels con-
taining water ; this precludes the nuisance of their becoming
cemented together by the drying up of liquids contained
between them. Two small jam-pots are sufficiently good
receptacles, that for the cover-glasses being the smaller, and
having preferably a curved bottom ; the water should be
renewed frequently, and if slightly acidulated, deposition of
Carbonate of Lime is prevented ; or distilled water may
be employed. After cleaning and drying, it is a good plan
to keep the cover-glasses and slips in a wash-leather case,
sewn into separate compartments. (Fig. u.)
The microscope should stand on a steady table or desk
of convenient height, say from 24 to 30 inches, according
to the size of the instrument. Should the room be subject
to vibrations from machinery, etc., it is well to have the
legs of the table on thick India-rubber pads, and the
microscope on a sheet of the same material. It is decidedly
better to work seated, and a revolving study chair is a great
convenience. The instrument should be placed in a good
* A little turpentine may be used if necessary to remove Cedar and other oils.
1 8 On Manipulation.
light, preferably a N.W. to N.E. aspect, as direct sunlight
is unsuitable for the higher magnifying powers : diffused
light, such as that from large white clouds, gives the best
field. The microscope may be placed fairly close to the
window, but care must be taken to have the mirror opposite
a clear and clean pane.
It is convenient to have a small sink and water-tap close
by, with a shelf for sample bottles and glasses, and a
In attaching objectives it is advisable to hold them up
with the left hand, whilst screwing on with the right fore-
finger and thumb.
The mode of treatment, the particular combination of
eye-piece and objective, and the degree of illumination, are
necessarily determined by the size of the object, and the
condition in which it exists. With objects such as a Hop
cone or Barley corn, a magnification of 30 or 40 diameters,
secured by the A eye-piece and i^ or i in. objective
would be adequate for a general examination, the object
being simply placed on a glass slide, and illuminated by the
Bull's-eye condenser as in Fig. 12. Successive portions of
the above-mentioned objects might then be taken, and
finally, the smallest portions examined by the high power
combinations, such as A eye-piece and \ objective, or
B eye-piece and \ objective, giving 300 to 400 diameters ;
and transmitted light from each mirror tried, as well as the
reflected light from the Bull's-eye condenser.
The observer will soon notice that the position of every-
thing viewed through the ordinary microscope is inverted,
and for a time this will be found a difficulty, especially
when working the stage movements : an appliance termed
an Erector restores the position, but is seldom used ;
practice removing the difficulty.
When the separate particles of a substance are invisible,
or barely visible to the unassisted eye, and insoluble in
On Manipulation. 19
water, it is often advantageous to examine them in this
latter medium as well as in the dry state, equal illumina-
tion and a flatter field being secured. Finely divided sub-
stances that are soluble in water (and also insoluble ones)
can often be examined with advantage in some other
medium, such as Gum Dammar, Canada Balsam, Glycerine,
In the Brewery, the substances requiring a high power,
such as Yeast, Beer sediments, etc., are generally in a
liquid state, and can often be placed on the slide just as
they are, or as it is advisable not to have the field too
full of objects they may be first diluted with water to the
required extent. A drop of liquid just sufficient to spread
beneath the cover-glass, may after a few trials, be accu-
rately judged, and thus prevent the necessity of wiping < ff
2o On Manipulation.
superfluous liquid, always an untidy matter, and requiring
considerable care to avoid more or less disturbance to the
specimen under examination. When examining this class
of object, frequent alteration of the focus is necessary, and
the fingers of one hand may be kept on the fine adjust-
ment, whilst the slide, or stage movements can be con-
trolled by the other hand.
Until some experience has been acquired in the manipu-
lation of the microscope, there is a risk, when focussing
with high power objectives, of passing the focal point
unawares, and driving the objective down with more or
less force on the cover-glass and slide : although the
spring of the objective socket where a spring is pro-
vided may prevent an accident, still fracture of a cover-
glass and slide sometimes results, accompanied possibly by
damage to the objective itself. To obviate this risk, it is
better first to gently run the objective down close to the
cover-glass, simply taking a view from the side of their
relative positions ; then focussing upwards, and away from
the cover-glass with the eye applied to the tube.
A useful selection of minute dissecting instruments may
be obtained by mounting needles in small wooden handles,
and after softening them in a spirit lamp or other flame,
grinding cutting edges, and bending to desired shape.
For most Brewery work, a few pipettes or dropping
tubes, and some glass rods with somewhat pointed ends,
suffice to place the objects on the slides. A neat and light
glass rod can be made from quill glass tubing (about \ in.
internal diameter), by the use of a mouth or stand blow-
pipe, or even with an ordinary gas or Bunsen flame.
A piece of Platinum wire fused into a glass rod is a con-
venient instrument for work with Bacteria, as it may so
readily be sterilised by heating red hot. A small wash-
bottle to hold distilled water, or bright clean well-water, is
very useful, and may be constructed either from a 3 oz.
On Manipulation. 2 i
narrow-necked bottle, or from a forcing flask (Fig. 13).
a is the blow tube and b the delivery. The same arrange-
ment of tubes does for both forms.
The following reagents in small stoppered bottles may
also be kept on or near the microscope table : weak
solutions of Ammonia, Iodine and Methyl Violet. The
use of these will be apparent later, and their preparation
is described in the Appendix under Reagents.
It is highly important that a reliable record should be
kept of all objects of interest, for the purpose of reference,
or in cases where any divergence from ordinary appearances
in well-known objects is presented. To do this effectually,
some little skill and practice in drawing are requisite, and
if these are not already possessed by the operator, should
be cultivated without delay. Written notes, remarks, and
date should be appended to these drawings, which had
better be contained in a sketch-book.
The Camera Lucida has already been referred to, as
also the Neutral-tint Reflector; for each of these a hori-
zontal position of the microscope is necessary, and this
constitutes a marked disadvantage in their employment ;
illumination, focussing and manipulation of the object being
22 On Manipulation.
rendered decidedly more difficult ; but on the other hand
the outlines and dimensions of objects may be obtained
with fair accuracy. In using either of these appliances, the
tube of the microscope is laid parallel to the surface on
which the instrument stands, so that the vertical height
from the centre of the eye-lens to the sheet of paper placed
underneath is about 10 inches (Fig. 14). The Camera
Lucida is then adjusted till the centre of the field of view
lies perpendicularly below the eye, and the image of any
object focussed by the microscope appears superimposed
on the paper below.
In the case of the Neutral-tint Reflector which is at a
fixed angle, it is generally only necessary to rotate the eye-
piece to which it is attached until the image is vertically
beneath. Outlines are first drawn with a fine-pointed
pencil, and detail filled in, partly with the reflecting arrange-
ment and partly by the unassisted eye or from memory.
A method that we have frequently employed for drawing
with the microscope and which answers well, is the follow-
ing: a small desk, with its upper surface sloping at the
On Manipulation. 23
same angle as the stage of the microscope when in use, is
placed close alongside the instrument on its right. A piece
of drawing paper is pinned on, and the left eye being applied
to the microscope, the image is seen by the right eye to
overlap the paper ; drawing may be carried on continuously,
both eyes being applied to the paper from time to time as a
In order to agree with any inclination of the stage, the
following elaboration of the desk is suggested. The top
is made movable by being hinged on to its box on the
side nearest the observer, the side farthest from him
being provided with curved brass bands, and setting screws
for each, so that the lid may traverse an arc of nearly 45
degrees. (Fig. 15.)
It is a good plan to first sketch lightly in pencil, and
then to etch with a fine pen and Indian-ink. The drawings
may be bounded by a circle, or a stencil-plate may be
obtained cut in copper, giving any desired margin.
It may be here remarked that with constant use of the
microscope it is a good plan to cultivate the use of either
An appliance is sold by some opticians consisting of an
ebonite disc, so fixed in relation to the eye-piece that the
unused eye of the observer is shielded and can be kept open.
Micrometer lines which are required for the measurement
24 On Manipulation.
of objects and the estimation of magnifying power, are con-
veniently copied by the Camera Lucida or Neutral-tint
Reflector ; or, the microscope being in its ordinary position,
the left eye is applied to the tube, whilst with the right eye
the observer marks dots corresponding with the magnified
lines of the micrometer, on a slip of paper held in front of
the stage, and then ruling parallel black lines through these
dots makes further comparison.
For the measurement of objects, either the stage or
eye-piece micrometer is employed, usually the former, the
latter not being of such general application ; it is custom-
arily ruled in hundredths and thousandths of an inch, or
parts of a millimetre. The lines as seen through any of
the combinations of lenses are depicted by drawing as
described, and on or between the lines so obtained the
object is drawn, and its relationship to them determined by
measurement. For instance, were half of the space in-
dicated by -rib of an inch filled, the linear measurement of
an object so filling it would be ^o inch, or were one-third
of a TWO inch space so occupied, the object would be ?oVo
inch in size.
The magnifying power of a microscope is not a definite
amount which can be fixed once for all ; it is dependent
upon the condition of the eye of the observer ; but in recent
times it has been customary to calculate the magnifying
power for a distance of ten inches, the average minimum
distance at which objects are distinctly visible to the normal
eye ; so that for the estimation of magnifying power with
the stage micrometer, the slip of paper should be placed
ten inches from the eye ; the lines then drawn being com-
pared with an accurately divided inch scale. Suppose,
for instance, five of the ToW inch spaces are required to
fill one inch, the power = ^- or 200 diameters, or if four
of the TOO inch spaces fill one inch the magnification would
be Hr 1 or 25 diameters. Plate I. shows some micrometer
A. eyep/ece & /'" object
A. to B eyepiece & / '" object. .
A ' foB eyepiece */6'" object,
or B eyepiece &/6 '? object. - .
immersion, . . _
1 1 1 1 1 1 1 1 1
.-fanh'mfitr*.*; and Mi///metres
--=i 00*% /coo* Inch x 40
< f -' inch x too
Comparison of M/crometer lines with Metric asid inch Sca/es
On Manipulation. 25
lines magnified with values attached (in one a yeast cell
is shown in its relative magnification), also the relation of
the micro-millimetre scale to the inch. English measure-
ments are frequently given in T^OO of an inch, whereas
foreign measurements are in T oVo of a millimetre or micro -
millimetre (/*) as it has usually been called,* and this
method is rapidly coming into general use. The relation-
ship of the thousandth of an inch to a micro-millimetre is
as i : 25.4.
This matter has been entered into in some detail, as it is
both interesting and useful to know the magnifying power
of the combinations, and the size of the objects under
Of course the most complete and valuable pictorial
records of objects are those furnished by the aid of photo-
graphy, but very few microscopists have, till recently, had
time or patience to pursue this branch of investigation,
the old methods requiring such cumbrous and expensive
apparatus. Some Burton friends of the authors have
latterly obtained excellent results with greatly simplified
apparatus, and in the Appendix a brief sketch of a suitable
and convenient method of Photo-micrography is given.
* As Physicists and Electricians have used this word micro-millimetre to indicate the
millionth of a millimetre the term MICRON has been suggested to express the thousandth
of a millimetre ; and in June, 1888, the word was adopted by the Royal Microscopical
A T various stages in the Brewing process we can, by
jf~\ the aid of the microscope, determine the presence
of organisms of various kinds, ranging from those originally
present in the materials, to those which are introduced up
to the very last by exposure to air. It is in the identifica-
tion and study of these, that the microscope has, for the
Brewer, its more important applications, and especially as
regards the organisms added in the form of yeast, which
substance, although containing in most cases a prepondera-
ting number of a desired species, is seldom free from forms
that are undesirable or positively injurious to the process.
Speaking generally, we may include the organisms with
which we have to deal in three important classes. First,
those provocative of alcoholic fermentation by the breaking
up of Sugars scientifically known as the Saccharomycetes.
Secondly, the moulds or Thallophytes, giving rise to objec-
tionable products of decomposition from a variety of sub-
stances. Thirdly, the Bacteria or Schizomycetes, inducing
changes which are, from the Brewer's point of view, mainly
useless or deleterious.
Besides these organisms we occasionally, in the case of
Brewing waters and in a few uncommon- instances, meet
Alcoholic Fermentation. 27
with some of a higher grade in the animal and vegetable
kingdoms, but they can hardly be considered as directly
affecting the Brewing process.
It is our purpose to consider the forms of life according
to the classification indicated above, which represents suffi-
ciently well their position in the scale of life, the lowest
organisms being those of Class i. Our attention is thus
first claimed by what for Brewers is the most important
group, viz., the Saccharomycetes or alcoholic ferments,
which in this chapter we will consider as regards their
In ordinary parlance the term yeast has been applied to
the surface scum or sedimentary deposit separated during
the fermentation of Wine, Beer, etc., in yellowish or
brownish masses, which, amongst foreign substances, con-
tain the organisms corresponding with alcoholic fermen-
tation the so-called alcoholic ferments the cells of which
compose the greater part of the separated yeast.
For a long time past, yeast has been used to excite fer-
mentation in Saccharine solutions, the yeast accruing from
one operation being the starting point of another. Prior to
the times of intentional addition of yeast, fermentation took
place either naturally or fortuitously in Saccharine liquids,
as for instance, in the expressed juice of the grape or of
other fruits, and very probably in Saccharine fluids pre-
pared from cereals, as in the case of the Maize beer, or
Chica of the Peruvians, and the Cerevisia of the Romans.
Even at the present day so-called spontaneous fermentation
leads to the production of certain beverages, including
some kinds of Belgian Beer.
All Saccharine liquids may be considered as capable of
giving rise to the phenomenon of fermentation, and espe-
cially the Saccharine liquids provided in nature, such as
fruit juices, etc., the character of a fermented product being
in any case dependent, of course, on the substances yielding
28 Alcoliolic Fermentation.
the fermentable extract. As regards Beer, we have to
deal with a beverage of relatively small alcohol percentage,
a fact which mainly accounts for the greater susceptibility
to change that it displays as compared with wine.
If a liquid in an active state of fermentation be filtered,
the suspended yeast may be removed ; and if this be com-
pletely effected, fermentation ceases. The yeast so removed
is capable, as is well known, of starting a fresh fermenta-
tion ; or it may be carefully dried off at a temperature below
1 00 F., and retain its power for a considerable period, but
the temperature of boiling water, or a short exposure to a
temperature over 130 F., as well as exposure to a very
great degree of cold, destroys its fermentative action.
Saccharine solutions which have been boiled in flasks in
the laboratory, cooled, and exposed to the air, frequently
enter into alcoholic fermentation ; but if, whilst hot, the
flask be plugged with cotton wool, the liquid contained in
it remains practically unaltered. We have thus evidence
upon the following points :
(1) That there is something in yeast which causes fer-
(2) That this property of yeast is destroyed by a high
(3) That the property is associated with particles that
may be separated from the fluid containing them by an
(4) That these particles may be contained in the air, and
may be separated from it by causing it to pass through
cotton wool. Microscopical examination of a drop of yeast
shows what the particles in question are. The earliest
recorded examination of yeast in this way was made by
Leuwenhoek in 1680, when he ascertained that it consisted
of small spherical and oval bodies, but failed to determine
their nature. About 150 years later, Cagniard-Latour took
up the work at the point that Leuwenhoek had left it, and
Alcoholic Fermentation. 29
added thereto the observations that the globules of yeast
reproduced themselves by budding, and thereby exhibited
properties including them in the vegetable kingdom. After
a short period of comparative inactivity in this line of in-
vestigation, Schwann, of Jena, and Klitzing, of Berlin,
independently, and almost simultaneously, re-discovered the
facts established by Cagniard-Latour, and so progressively
the nature of yeast became pretty clearly known. Since
then its life-history and functions have been minutely in-
vestigated by Pasteur, Reess, Hansen, and others, and
many distinct species of Saccharomycetes have been clearly
Some evidence has already been adduced in this chapter
as to fermentation being the result of a specific organism.
In reality no fact has been more clearly demonstrated by
scientific proofs provided more especially by the beautiful
and classical researches of Pasteur than that without the
presence of a ferment cell, fermentation cannot take place ;
and that the removal from, or the killing of, the organisms
in a fermentable solution suffices to bring any fermentative
action to an end. This statement need only be modified to
the extent of saying that it has been found by Lechartier
and Bellamy, and subsequently established by Pasteur*
that under certain conditions an internal fermentation takes
place in fruits, accompanied by the production of alcohol.
This phenomenon appears to be dependent on some kind of
residual vitality in the fruit tissue, and has no connection
with the definite ferment cells that were shown by Pasteur
to be adherent to the surface of fruit, especially the grape,
and capable of fermenting the expressed juice of the same.
Space does not permit us to trace the successive stages
of the researches alluded to, nor can we here review the
various theories as to the nature and mode of action of
* Etudes sur la Biere. Pasteur, p. 258, et seq.
Translation of same, Faulkner'and Robb, p. 266, et seq.
3O Alcoholic Fermentation.
ferments, that stimulated the prosecution of them. Pasteur
so completely cut the ground away from under the fanciful
theorists of the Liebig School, and showed so clearly the
organised nature of the alcoholic ferments proper, that the
only immediate point remaining undecided is, as to how the
cells exercise their functions ; whether action takes place
inside or outside the cell. Many scientists cling to the
idea of the diffusible matters of the saccharine fluid passing
into the cell, and there undergoing decomposition, whilst
others accept the theory enunciated by Nageli, that the
activity of the alcoholic ferments is due to vibrations of the
protoplasmic contents, communicated through the cell wall
to the substances immediately adjacent to it. The fact
that the thinnest membrane intervening between yeast and
a fermentable liquid prevents fermentation as shown by
Dumas is somewhat against Nageli's theory.
The destructive action, already spoken of, that heat
exercises on yeast, applies in a measure to organisms pro-
ductive of fermentations other than alcoholic. The absence
of all organisms and the consequent immunity of a liquid
from fermentative or putrefactive change, constitutes a state
of Sterility ; the only changes then possible being traceable
to other agencies than those under consideration, such as
oxidation by air, evaporation, etc., etc. Regarding the
yeast cell, then, as the direct cause of fermentation, we will,
after the briefest consideration of its chemical composition,
proceed to ascertain its appearances during the progress of
its fermentative career, contenting ourselves for the moment
with the knowledge that we are dealing with an organism
consisting of a simple oval or spherical cell, with an outer
envelope or cell wall, and internal viscid matter known as
The organic nature of yeast is easily demonstrated by
drying and charring in a silver or platinum dish ; a smell
similar to that of burning animal matter is produced, whilst
Alcoholic Fermentation. 31
a mass of charcoal and mineral matter is left, which, if com-
pletely incinerated, is reduced to a white ash, consisting
entirely of mineral matter. Chemical analysis proves that
yeast contains Carbon, Hydrogen, Oxygen and Nitrogen,
with relatively small quantities of Sulphur, Phosphorus,
Potassium, Magnesium, and Calcium. These elements are
variously combined to form the constituents of yeast cells,
namely, Albuminoid or Proteid matter, Cellulose, Fat,
Saline substances and Water. The envelope of the cell
contains the cellulose or substance resembling cellulose,
and some of the mineral matters ; the protoplasm containing
the protein compounds and fat with the larger proportion
of the mineral salts.
The above elementary matters must, of necessity, be
contained in some form in liquids destined for the produc-
tion of alcohol with a corresponding increase of yeast.
They are contained in malt worts, the sugar Maltose, fur-
nishing Carbon, Hydrogen, and Oxygen, as well as giving
rise to the alcohol formed ; whilst the Albuminoids and
Amides furnish the bulk of the organic constituents, espe-
cially Nitrogen ; and the phosphates and other salts of
Potassium, Lime, and Magnesium present in the worts,
provide the Inorganic or mineral constituents. As Pasteur
has shown, the simplest combination of substances that will
sustain yeast is a solution containing Sugar, phosphates of
Potash, Lime, and Magnesia, and Tartrate of Ammonia,
the latter supplying the required Nitrogen : the power of
manufacturing protein from Tartrate or other salts of Am-
monia, being a distinct peculiarity of vegetable life.
Yeast usually has a slightly acid reaction, and grows
better in an acid than an alkaline liquid. The variation in
the conditions of nutriment affecting yeast involve con-
siderations which, being chiefly of a chemical nature, are
scarcely in our range. The microscope may well be em-
ployed to detect such differences caused in the appearance
32 AlcoJiolic Fermentation.
of yeast, but does not necessarily afford an explanation of
them. We shall, therefore, confine ourselves to mentioning
at the end of this chapter some general considerations in
connection with malt worts, and will now proceed to the
microscopical examination of yeast, and the study of the
yeast cell as a complete organism. We may prepare some
yeast for viewing, as follows : A clean glass slip is taken,
and by means of the wash bottle (Fig. 13) or a pipette, a
small drop of clean water is placed in the centre. The
sample of yeast, which may conveniently be contained in
a small tumbler, is now thoroughly stirred with a pointed
glass rod, which, before withdrawal, may be rotated against
the sides of the vessel to remove the excess of adhering
yeast. The rod is then carefully dipped in the water-drop
till a quantity of yeast is introduced sufficient to impart a
slight milkiness, when the drop is stirred with the clean
end of the glass rod. A cover-glass is now put on, and
gently pressed down with the finger-nail, any liquid pressed
out being removed with a small piece of blotting paper.
Another method of preparing yeast for examination is to
stir a small quantity into a wine glass of clean water, and
take a drop of this for the slide. We prefer, however, to
use the first method.
When viewing yeast for the first time, it is instructive to
use an objective magnifying some 40 or 50 diameters, in
order to realise what a very minute organism is being dealt
with. Afterwards the combination giving about 300 dia-
meters may be used, this being the power generally appli-
cable to the examination of Yeasts, Beer residues, etc., etc.
With this degree of magnification we see a collection of
cells of spherical, oval or ovoid form. These cells consist
of a thin-walled sac or bag, containing a somewhat viscid
fluid. We have already spoken of these respectively as
cell-wall and protoplasm, their scientific designations.
The cell-wall is an integument which, although thin, has
Alcoholic Fermentation. 33
considerable elasticity and resisting power ; it may how-
ever be burst by a sudden shock, such as a blow upon the
cover-glass with the blunt end of a lead pencil ; when the
protoplasm is seen to have emerged from the sac, whose
nature can now be distinctly ascertained.
On examining perfect cells more closely, we become
aware of differences in the nature of the protoplasmic con-
tents ; in some parts of the cell it is decidedly clearer than
in others. These clear portions are called the Vacuoles
(shown in Fig. 16 on diagram scale), and are considered to
Fig. i 6.
have their origin mainly in the withdrawal of nourishment
from the protoplasm of the parent cell during the repro-
ductive process ; the protoplasm being replaced by trans-
parent cell-juice, as Reess terms it, probably of a more
aqueous nature than the rest of the protoplasm. At the
same time it is by no means certain that the vacuoles
cannot appear and be well marked apart from such action.
We are inclined to believe they can. In any case their
appearance is very much influenced by varying conditions
of temperature and aeration where reproduction does not
Healthy yeast cells usually show at least one vacuole,
but often two, and sometimes three. Inside the Vacuole
may be seen small granules, and these not unfrequently
move actively in the clear protoplasm. We have known a
34 Alcoholic Fermentation.
"Stone Square" yeast and specimens of London yeast
show this very plainly. The granules are called Nuclei
(Fig. 1 6).
On examining full-sized, well-vacuoled cells carefully, a
dark spot may be frequently detected, which on causing the
cell to shift its position by touching the cover-glass, press-
ing it slightly, or in some other way imparting movement,
is seen to lie on the cell wall. This is the point at which
the bud is appearing. This bud or young cell (Fig. 16)
gradually enlarges, drawing its supply of nourishment from
the parent cell till it attains about the same size ; the area
of attachment then decreases till the young cell becomes
detached from the parent, and goes forth fitted to procure
a living for itself. There is no doubt that the same cell
can bud more than once, and in some cases at more than
one point of its envelope at the same time. Pasteur, by
continued observation of a budding cell, found that at the
end of two hours it had produced six daughters, or that the
two (i.e., the cell and its bud) had become eight cells. The
enormous rate of multiplication thus indicated does not, of
course, take place in the Brewery, where a comparatively
large excess of yeast is employed. Still the reproduction
The functions of the Vacuoles and Nuclei is not under-
stood, but they may be taken as indicative to a certain
extent of the age and degree of activity of the cell. Take,
for instance, some of the yeast thrown up last of all in a
skimming fermenting vessel, or the last part of the spurge
from unions or cleansing casks. It consists very largely of
new cells which show no differentiation of the protoplasm,
that is to say, no vacuoles or nuclei. They are homogeneous,
and possess an appearance of uniform semi-transparency.
Plate II., Fig. la. Such cells are the recently-formed ones,
and cannot be considered as having arrived at the full
degree of activity, which we believe we are correct in
Deuelopment of Yeast.
Sporulatton of Yeast .
. WRIGHT. OfL
BEMPQSE & SONS. LIT*
Alcoholic Fermentation. 35
ascribing to the completely differentiated ones. After a
rest of a day or two these new cells begin to show vacuoles
(Plate II., Fig. i, b and c), and in a fresh fermentation
become parent cells, d, e, f. These phases of development
are progressively represented in the figure, the cell arriving
at its full maturity, and reproducing its typical form by
budding. During every normal fermentation a small pro-
portion of the cells deteriorate and die, owing probably to
natural decay, after passing through several fermentations
with repeated reproduction. The growth of yeast under
unfavourable conditions of nutriment, temperature, &c., will
increase the proportion of dead cells, besides weakening
both old and new cells.
The progressive changes in appearance following the
separation of yeast from the fermented liquid are, under
ordinary conditions of storage, an apparent thickening of
the cell-envelope, the enlargement of the vacuoles, or the
coalescing of all vacuoles into one, accompanied by a
greater sharpness about the nuclei (see Plate II., Fig. i g).
The next stage is that the whole protoplasm begins to
grow dense, and takes on a speckled appearance, the cell
lessening in size (h).
The cell shrinks still further from yielding up of cell-sap,
the protoplasm becoming quite granulated (i), and fre-
quently showing a slight yellowish green tint. The final
diminution of the cell is to about \ or f its original
diameter, and at this stage it is probably dead, for it is
difficult to give a precise point in the decadence at which
the cell is incapable of revival ; it being certain that yeast
cells apparently dead are sometimes only torpid, and may
begin to grow and give rise to fresh fermentation in a
stimulating liquid. For all practical purposes we may,
however, regard the small granulated cells in any sample
as useless. A very good method of distinguishing between
living, and dead or torpid cells, is based on the resisting
36 Alcoholic Fermentation.
power that living cells exhibit to dyes. It consists in
running a little solution of methyl violet or carmine at the
side of the cover-glass, and causing the dye to traverse the
yeast under examination by applying a small piece of blot-
ting paper to the opposite side. The proportion of cells
stained is noted. If the dye solution be weak the active
cells do not stain, the torpid cells stain slightly, whilst the
dead cells show a deep colour. Weak iodine solution may
be used for the same purpose, the dead cells staining brown.
A somewhat more convenient mode of manipulation is to
put a drop of dilute stain or reagent on the slide and stir
the yeast into it.
Yeast is capable of reproducing itself in another very
interesting manner by the formation of internal spores,
known as Endospores or Ascospores, the process being
termed multiplication by Endogenous division. The ordi-
nary forms of Saccharomyces seldom or never exhibit this
phenomenon in fermentation. It is induced by withdrawing
the yeast from fermented liquids, and exposing in a moist
condition on a plate of some porous material such as Plaster
of Paris, or on slices of potato. Frequent examination is
made with the microscope, and where the phenomenon
occurs, the protoplasm is seen to gradually separate into a
number of parts, usually four, each of the portions ap-
proaching a spherical form, and becoming surrounded by
an envelope of its own. (Plate II., Fig. 2.) As these
ascospores reach their maximum size, the old cell wall gives
way and they escape, and in a nutritive solution are capable
of budding, giving rise to ordinary yeast cells again.
The first communication on this subject was made by
De Seynes in 1868. He observed ascospore formation in
Mycoderma Vini. Reess's work followed, describing asco-
spore formation in several kinds of Saccharomyces, The
better method of cultivation, viz., on plaster blocks, was
introduced by Engel, and other investigators have con-
Alcoholic Fermentation. 37
tributed points of information. Hansen, however, has
made the subject his own, and put the ascospore formation
on a well defined basis as regards conditions of time, tem-
perature, etc. He ascribes the failure of other investigators
in obtaining ascospores, to the fact that only young and
vigorous yeast sporulates. He has obtained ascospores
from English yeast as well as Foreign yeast of various
kinds, and makes use of the ascospore formation to deter-
mine the identity of any given yeast. In another chapter
we shall go somewhat further into this matter.
Having thus acquainted ourselves with the chief facts
relating to the life history of yeast, we will conclude this
chapter with some general considerations regarding in-
fluences obtaining in the Brewery, which tend to modify
the microscopical appearance of the ferment. Speaking
generally, Low gravity malt worts may produce clean and
uniform looking yeasts, but they are seldom vigorous ones.
Malt worts of medium gravity other conditions being
favourable produce the most uniform yeast.
High gravity malt worts produce a vigorous yeast, but
not of uniform type, and capable of greater fermentative
than reproductive power.
The foregoing remarks apply also to cases where a
moderate proportion of Brewing sugar is used.
Another set of conditions influencing the activity and the
microscopic appearance of yeast, is the range of temperature
through which it has been taken in the fermentation.
Taking into consideration all known kinds of yeast, we find
that the phenomenon of fermentation is exhibited at all
temperatures between 32 F. and 130 F. but for the
majority of species, temperatures ranging from 54 75 F.
are the most favourable. The pitching temperatures of the
United Kingdom (distillers' fermentations excepted) ap-
proximate to the lower figure, and the maximum tempera-
tures attained, are some degrees below the higher. Now
38 Alcoholic Fermentation.
confining ourselves to the range of temperature employed
in English breweries, apart from other modifying influences
of greater and less importance, we believe that low tem-
peratures, as a rule, produce the cleanest yeast but not the
most active. High temperatures tend to produce an un-
clean yeast of considerable activity, but liable to rapid
Intermediate temperatures produce a good type of yeast
and of reasonable cleanliness. Every system of Brewing
has its own most favourable range of temperature for fer-
mentation, discoverable from the character of the yeast and
the nature of the Beer produced, other conditions being of
course adapted to a favourable result.
Another factor of considerable importance, influencing
the activity and consequently the appearance of yeast, is the
degree of Oxygenation of the worts ; that is the amount of
oxygen dissolved or held in loose combination at the time
the worts reach the fermenting vessel. Now, although
yeast can live and increase in saccharine solutions without
free oxygen, yet it is only to a limited degree, and for
continued and vigorous fermentation, oxygen is absolutely
necessary. During the apparent quiescence of the yeast
for many hours after pitching at a normal temperature, the
dissolved oxygen is being absorbed by the living cells, and
on the supply being practically exhausted, the yeast in-
vigorated to a corresponding extent, commences to attack
the saccharine matter, and the production of alcohol and
carbonic acid gas commences, the yeast meanwhile entering
on the stages of its reproductive career, which with the
assimilation of nutrient matters from the wort, goes on till
the fermentation ceases. A stock of fresh cells is provided
far in excess of those which naturally expire in the process,
the new cells retaining under normal conditions the charac-
teristics of their progenitors.
Returning for a moment to aeration or oxygenation,
nothing tends more to the production of a feeble dete-
riorated yeast than insufficient oxygenation of worts, and
under ordinary Brewery conditions (i.e., in absence of
special aerating apparatus), worts cannot very well be over-
In a normally attenuated beer brewed with a clean and
good type of yeast, a slow fermentation goes on in cask,
which, when caused by ordinary yeast or Saccharomyces
Cerevisiae, seldom gives trouble, but unfortunately for the
Brewer the secondary fermentation is not unfrequently set
up by strange ferments, better able to exist under the ob-
taining conditions than Sacc. Cerevisiae, especially where
the original worts were not of proper character. This is
the cause of so-called Fret, Sickness, etc., which are
described in connection with the particular ferments
associated with the changes.
Summarizing the action of yeast in malt worts as regards
its life history, we then have
First ; the time of rest or of no visible signs of fermenta-
tion. During this period the yeast absorbs oxygen, and
commences its vegetative and assimilative functions.
Secondly ; the period of increasing activity, the yeast
rapidly attacking sugar, the formation of new cells pro-
Thirdly ; the slackening and ending of the primary fer-
mentation during which the active yeast is mainly conveyed
to the surface.
We advise the student to carefully examine specimens of
yeast taken at various stages of fermentation and cleansing.
ALCOHOLIC FERMENTS OF THE ENGLISH PROCESS.
THE researches of Pasteur were unquestionably the
starting point of all important investigations in
connection with fermentation, and they may be considered
as having largely contributed to elevate Brewing to a
scientific industry ; for although the microscope had been
employed in Burton and perhaps elsewhere in the King-
dom, for the selection of yeast, Brewers, as a body, awoke
to the fact that the condition of their yeast was of chief
importance as determining the production of a satisfac-
tory beer. The main point of Pasteur's researches was
the indication of the danger to be expected from organisms
capable of producing Acetic, Lactic, and Butyric acids, and
other objectionable products ; and the means of removing
such risks or reducing them to a minimum. At the same
time he by no means lost sight of the possible influence of
strange forms of Saccharomyces ; but doubtless at the time,
this did not appear to him the chief issue involved. His
work, we need hardly say, marks a distinct epoch in Brew-
It will be plain, from what has been already said, that
the term yeast is indefinite, as one or many things are
covered by the same term, and the word ferment alone is
Alcoholic Ferments of the English Process. 41
not any more precise, including as it does at present,
organized ferments such as the Saccharomycetes, Moulds,
and Bacteria, besides substances having a curiously specific
action, such as Invertin and Diastase, which are unorgan-
ized ferments. Despite its occasional impurities, we may
regard Brewers' yeast as consisting of the cells of a living
vegetable organism capable of decomposing the saccharine
matters existing in worts, forming therefrom Alcohol and
Carbonic Acid gas with a small percentage of what may be
considered as bye-products, e.g., Glycerin, Succinic Acid,
After these preliminary remarks, and having already
described the life-history of the yeast-cell generally, we
may now address ourselves to a consideration of the defi-
nite alcoholic ferment forms exhibited by the beers brewed
in the United Kingdom. So far as our present knowledge
goes, we have to deal with the following species :
and one or two species of rarer occurrence,
Saccharomyces Apiculatus, .
besides certain organisms which may at times act as alco-
holic ferments, viz. :
Mucor Racemosus (ferment form).
The different yeasts in use throughout the United King-
dom, vary so considerably as regards appearance and degree
of activity, and give rise to Beers of such essentially dif-
ferent character, that mere modification of one species of
* We suggest this as a convenient title for the Caseous ferments, of which there are
probably two or more varieties.
42 Alcoholic Ferments of the English Process.
Saccharomyces by differing conditions of the process, would
seem to afford a quite inadequate explanation of such diver-
gencies, and it is more than probable that different varieties,
if not species, of Saccharomyces Cerevisiae are in use at the
Failing more exact knowledge, however, we may for the
present regard the large proportion of cells in a clean and
active yeast as being those of Saccharomyces Cerevisiae,
and we may well acquaint ourselves first with the ap-
pearance of yeast grown under different conditions, but
relatively pure in respect of the absence of Bacteria, and
obviously unusual or "wild" forms of yeast. Plate III.,
Fig. i shows a typical sample of Burton yeast of a high
degree of purity and fermentative vigour ; the features
worthy of observation are : The uniformity of the shape,
size, and appearance generally. The tendency to an elliptic
or ovoid form. The clearness of the vacuoles ; and lastly,
the absence of extraneous matters.
Plate III., Fig. 2 represents a specimen of London
yeast of good quality. It will be noted that there is not
the same regularity of size and shape ; that the cells are
throughout larger ; and the internal features vary to a
not inconsiderable extent. In some cells the vacuoles are
unusually large, and the nuclei very distinct. We may
here remark that, besides differences in the character of
nutriment, the higher ranges of temperature of fermentation
tend to increase the size and diminish the uniformity of
yeast cells. There is probably a relationship between these
facts and the appearance of London yeast, of which the
plate represents, we consider, a typical specimen.
The other characteristic yeasts of this country are, we
should say, the Scotch slow yeast and Stone Square yeast,
both of which, considered from the point of view of their
appearance under the microscope, occupy a position inter-
mediate between London and Burton yeast. They are
/. L. Wright, d&l.
Fia.2. London Yeast.
: X 360 diasn r
West . Newman & Go, So.
Alcoholic Ferments of the English Process. 43
usually somewhat irregular, and generally well-vacuoled,
especially the " Stone Square," in which the nuclei are
often remarkably distinct and large.
The average diameter of the cells of ordinary Brewery
yeast is about Woo inch or 8 micromillimetres (/x).
The microscopical characteristics which, as a rule, denote
an active and healthy yeast, are the following : Uniformity
of size and shape. Sharpness of cell outline, indicating a
strong cell-wall. Presence of vacuoles, which should be
clear and of fair size, neither large nor small ; for if the
vacuoles are barely perceptible the yeast is probably too
young for use, and if the vacuoles are large it is a
sign of exhaustion by much previous reproduction, or
unfavourable conditions attending its growth. The nuclei
should not be too plain, though as already mentioned,
some yeasts show nuclei much more distinctly than
others, so that due allowance must be made for the par-
ticular process by which the yeast has been produced.
There should be no noticeable proportion of dead or
granulated cells, or foreign matters such as strange yeasts,
filamentous bodies, "grounds," or dirt of any kind. To
emphasize these remarks, and in contrast to the plates
already shown, two fields of yeast are represented in Plate
IV., Fig. i being the Burton yeast of Plate III., Fig. i, in
a deteriorated and granulated condition, quite useless for
pitching ; whilst Fig. 2 shows an exhausted yeast, accom-
panied by an excessive amount of extraneous matters.
As we proceed, we shall enter more fully into the various
causes of yeast deterioration, and the appearances in con-
nection with the same ; at present it is sufficient to speak
of the signs of degeneration traceable in the cells alone :
they are the following :
Unusual thinness or thickness of cell-wall, more especially
Abnormal clearness and largeness of the vacuoles.
44 Alcoholic Ferments of the English Process.
Very distinct nuclei (except under certain conditions
Speckled appearance of the protoplasm.
Smallness of fully matured cells (except in the case of
yeasts from very strong ales).
Large thin-walled cells.
Irregularity in size and shape.
And lastly, any marked percentage of dead or torpid
We strongly advise the student to examine yeasts from
all sources open to him, and to draw typical fields in a
suitable book, appending notes to each specimen as regards
its source and age, and any marked peculiarities of appear-
ance. It is true it requires much practice to draw yeast
successfully, but it is worth the trouble, for if the drawings
are not masterpieces, the mere attempt to make them
will impress certain facts on the mind, when otherwise
there would probably be no lasting recollection of the
specimen. A hard pencil and smooth drawing-paper are
sufficient, but if desired, the pencil sketches may be ren-
dered into pen-and-ink etchings, though this is even finer
work than pencil drawing.
We may now consider the alcoholic ferments other than
Sacc. Cerevisiae, commencing with
This name has been conferred on a ferment which was
first identified by Pasteur in the secondary fermentation
of wine, and later, of^Beer.
Reess also noticed its presence towards the close of
vinous fermentation. He adduces some not very strong
evidence as to its inability to ferment cane Sugar.* Grape
sugar would appear to be easily fermented by it.
* Untersuchung.en iiber die Alcoholgahrungspilze. Dr. Max Reess, p. 29, foot note.
X 350 cjiamr'
S . Pastor i an us. x 3f>O.
Caseous Yeasts, x 360.
L.H. N? I. ff.W. N2.
S.Exiguus. x 300.
L.H. After R&O.SS. B.H. M.&L.
S. Ellipsoideus. x3OO
L.H. After Fteess. R.H. NI.AL.
J.E. Wright, deJ.
Mycoderma. Vini x 300.
L.H.Aerobian form. R.H. Submerged form.
West, Newman A Co, So
Alcoholic Ferments of the English Process. 45
Plate V., Fig. i represents the ferment as it is generally
seen in English Beers. The peculiar elongated cells will be
noticed, which bud towards one end of the longer axis and
generally on one side of it. The cells of S. Pastorianus,
when growing freely and in a state of purity, show a
tendency to become a shorter ellipse ; the vacuoles being
With a ferment so variable in size, it is difficult to give
representative dimensions ; the shorter axis is about
4 6 ju long, whilst the longer axis may attain 18 22 \JL
under ordinary conditions.
S. Pastorianus is a common cause of the secondary
fermentation of English Beers, and doubtless frequently
plays a part, as an accompaniment of several other ferments.
It has been shown by Brown & Morris* that S. Pastorianus
and also S. ellipticus unlike ordinary S. cerevisiae are
able to ferment Malto-dextrin. When growing alone,
or in large proportion, S. Pastorianus may give rise to
very troublesome " frets ; " for often comparatively little gas
is formed in relation to the number of cells visible, and
these last have, in the earlier stages of their development,
a great tendency to remain suspended in the Beer, owing
probably to the slight specific gravity of the cells. Its
growth seems to be facilitated by the presence of an undue
amount of dissolved oxygen in finished ales. We have
frequently seen samples of ale, taken in bottles about the
time of racking, develop an active S. Pastorianus fermen-
tation within 36 to 48 hours, the quantity of cells being
remarkable, but the gas-evolution comparatively slight.
The ferment may be often found in the deposit of bottled
beers that are fit for consumption.
" Forced " Beers not unfrequently show S. Pastorianus,
and, as in the case of other kinds of Saccharomycetes
similarly developed, a much greater variety of form is
* Journal Chem. Soc. Trans. Vol 47, 527.
46 Alcoholic Ferments of the English Process.
exhibited, owing probably to the elevated temperature
(80 F.) of the Forcing Tray.
As regards the conditions of the Brewing process that
give rise to S. Pastorianus, we can only say that the
following are probably amongst them :
Impure state of the " Store" yeast as regards foreign
ferments or " wild yeast."
Insufficient attenuation and yeast production.
A combination of fineness and flatness at Racking in
conjunction with inadequate attenuation.
Although a " Pastorianus fret " is frequently accom-
panied by a distinctly unpleasant smell and flavour more
especially the former still the fret may pass off and be
succeeded by a normal fining with gas production and
disappearance of the unpleasant accompaniments of the
S. Pastorianus growth. Frets induced by other forms of
Saccharomycetes occasionally pass off in a similar way.
Dry hopping undoubtedly introduces many " wild " forms
of yeast, and probably amongst them S. Pastorianus,
so that with a predisposition on the part of the ale to
nourish this particular ferment, its growth readily follows,
especially when the ale being racked very bright, S.
Cerevisiae is in deficiency.
THE CASEOUS FERMENTS.
In the course of his researches* Pasteur encountered a
kind of Saccharomyces whose cells showed a curious ten-
dency to agglomerate and form a curdy or cheesy mass.
He obtained it from Burton yeast by exposing a nutrient
liquid set with this last, to a temperature of 122 F. for
i hour. A ferment survived this treatment, and exhibited
cells closely allied in form to the elongated ones of S.
Pastorianus, giving as well, shorter club- or pear-shaped
* " Studies on Fermentation," trans, by Faulkner and Robb, p. 200 et seq>
Alcoholic Ferments of the English Process. 47
cells. Plate V., Fig. 2, left half disc, is a drawing of what
we believe to be an identical yeast which we have seen in
Bottled beer deposits and Forced ales. On cultivating his
caseous yeast in an artificial medium Raulin's fluid (for
composition see Appendix C) Pasteur found that oval
and spherical cells were developed, but on restoring the
ferment to worts, the original irregular and pear-shaped
The year before last, one of us described in a paper
before the Laboratory Club,* a caseous ferment obtained
from Burton yeast, which seems to be dissimilar to that
described by Pasteur ; for when grown time after time
in Bitter wort, it consists of spherical cells [Plate V.,
Fig. 2, right half disc], of 1 to f the size of ordinary S.
Cerevisiae, and under no condition assumed the pear-shaped
form, although quite 30 or 40 Ibs. weight of the ferment
must have been handled in the various experiments made
with it. For the present it may be convenient to call this
ferment Caseous Yeast No. 2 ; and Pasteur's, No. i.
The experiments with Caseous Yeast No. 2 led to the
following conclusions :
That the ferment possesses a degree of activity hardly
inferior to S. Cerevisiae at from 60 to 70 F. Above
70 F. its activity appears to be greater and it suffers less
deterioration than S. Cerevisiae. Attenuation also goes
further, owing probably to the breaking up of M alto-
dextrin. It acts mainly as a bottom ferment, very little
going into suspension, except at elevated temperatures,
when it has a tendency to break up. A curious feature
about the yeast is that it takes up little or no resin from
hopped worts, and thus, leaving all the more in solution,
produces a beer with a marked resin bitter. An increased
production of acid is also a feature, the normal acidity
* Transactions of the Laboratory Club, Vol. I, pp. 32 and 33. "Some of the causes
of the deterioration of Brewers' Yeast," by C. G. Matthews.
48 Alcoholic Ferments of the English Process.
being nearly double that of ordinary sound ales. The Beer
has something of a " Lager" flavour, is very stubborn in
brightening, and the keeping properties are of an inferior
It will be obvious from these facts that the presence of
this ferment in quantity in pitching yeast would be a
distinct disadvantage, as a peculiar harsh flavour, a yeasty
or resinous bitter and a cloudy beer, would be not unlikely
consequences. Mixtures of one-half Caseous yeast No. 2,
and one-half Burton pitching yeast, when fermented with
a rich wort gave decidedly unsatisfactory beers ; and pro-
bably a much less proportion of the Caseous Yeast would
do the same.
We believe these Caseous Yeasts to be of much com-
moner occurrence than is generally supposed ; for instance,
a specimen of Lager Beer yeast sent to us by a friend, and
said to be derived from an originally pure selected yeast,
assumed a strongly-marked caseous habit after putting it
through one fermentation at 60 to 65 F., and retained the
same so long as it was cultivated. Caseous yeast No. 2,
is one of the Saccharomyces forms found not unfrequently
on dry hops ; it may often be seen in Bottled ales, Forced
samples, and even the deposits of Racking samples some-
times give indications that lead one to suspect its presence :
we allude to the agglomerating tendency of the cells.
The diameter of the cells of No. 2 is some 5 6 n. An
average for the long axis of the forms of Pasteur's Caseous
ferment is about 10 n. We have good reason for believing
that there are several varieties of this ferment, for which
we suggest the name Saccharomyces Coagulatus, as being
much more in accordance with the properties of the
ferments, than the term Caseous yeast.
Alcoholic Ferments of the English Process. 49
This ferment sometimes called S. Ellipticus was first
noticed by Pasteur, and subsequently described by Reess
in connection with the alcoholic fermentation of wine, in
which it is of common occurrence. It is by no means
uncommon in Beers, and is easily distinguished from S.
Cerevisiae, but perhaps with more difficulty from S. Pas-
torianus. Plate V., Fig. 3 shows the uniformly elliptic
cells, one half the disc the left hand being a reduction
of Reess's drawing of the ferment, whilst the other half
represents it as we are accustomed to see it in ales.
Long axis about 6 ju, short axis 2.5 /* The much
greater size of Reess's cells may either indicate, a distinct
variety of the ferment ; the effect of a more congenial
nutrient solution ; or a different appreciation of the mag-
nifying power of a microscope.
The smaller form of S. Ellipsoideus, the one which
more particularly concerns us, is not unfrequently found
associated with cloudy " frets" and "sickness," and in such
cases may grow pretty freely. It is probable that Beers
brewed from very hard waters are more open to this form
of secondary fermentation than others. With the first-
mentioned ales a decided " stench " often comes on, owing
to the production of Sulphuretted Hydrogen, and from this
traces of sulphur alcohols, a strongly unpleasant smelling
class of substances. These effects wear off however, and
a beer which has been through a very bad Ellipsoideus
fret may, if otherwise sound, become quite palatable.
S. Ellipsoideus is frequently met with in bottled ales and
" forced " samples, but is not always accompanied by smell,
but so far as our experience goes a bad stench is generally
accompanied by Ellipsoideus. There is some evidence*
that S. Ellipsoideus tends to impart a vinous scent and
* Claudon & Morin. Compt. Rend, 104, pp. 11091111.
50 Alcoholic Ferments of the English Process.
flavour to Beer wort, and an acidity of about twice the
normal amount. It has been lately suggested that S.
Ellipsoideus should be utilized for the production of a
vinous unhopped beer or Barley wine ; but we question
whether the taste of the public is in accordance with a
beverage of this description.
Under this name, Engel describes a ferment obtained
by him from leaven of flour, and to which the leaven owes
its activity. It consists of budding cells of a globular form,
the diameter of the largest being 6 ju. In Pasteur's fluid
it produced only a slow fermentation. The cells placed
under favourable conditions sporulated.
A ferment form corresponding with Engel's is some-
times met with in Beers [Plate V., Fig. 4], and we may
conveniently consider this to be S. Minor. Average
diameter 3 4 ju. A free growth in beers under ordinary
conditions is rare. We have seen it in Racking beers
to the extent of i to 2 per cent, of the cells present,
and in larger quantities in forced ales. Also in a few cases
of fret accompanied by persistent cloudiness with flatness.
When present in Racking samples it is usually to be
detected amongst the Store yeasts. Like other ferments,
it is quite possible it may occasionally be introduced with
dry hops. Beyond the fact that its presence in ales denotes
yeast impurity, and probably high finishing temperatures in
fermentation, either in the " Square" or by subsequent rise
of temperature in cleansing vessels, there is little to be
Described by Pasteur and Reess as adherent to fruits,
>g-, grapes, and associated with vinous fermentation, has
Alcoholic Ferments of the English Process.
been made the subject of a special research by H arisen.*
It presents the appearance depicted in Fig. 17, being
pointed at each end. It measures from 4*5 7 ju largest
diameter, and 2 3 M wide. It has been seen in Belgian
Breweries where spontaneous fermentation is employed, and
to a limited extent in other foreign beers ; but according
to our experience is hardly ever met with in English beers,
though occasionally doubtful specimens of it occur in forced
Hansen's observations of the ferment contain much that
is interesting. He found that during the winter, the cells
of the ferment were resident in the earth, underneath the
shrubs on which it appeared during late summer and
autumn, and that the appearance of it was more especially
on certain fruits as they ripened plums, cherries, goose-
berries, etc.t The descent of rain, or falling of the ripe
* Meddelelser fra Carlsberg Laboratories Tredie Hefte, 1881.
t Pasteur had previously found that ferment cells appeared on the grape at the time of
ripening. Etudes sur la Biere.
52 Alcoholic Ferments of the English Process.
fruit to the ground, caused the cells of S. Apiculatus to
become intermingled with the soil, in which it rests during
the intervals between its appearance, retaining its vitality
until such time as it is liberated by the drying up of the
soil and its dispersion as dust.
Hansen shows that S. Apiculatus does not always bud
into the typical forms, but may give rise to distinctly oval
cells, and also irregular or abnormal forms according to the
conditions of nutriment, which when favourable, determine
the production of a large proportion of apiculated cells. It
ferments Beer-wort feebly, acting as a bottom ferment, and
never producing more than i per cent, of alcohol, when
S. Cerevisiae would produce 6 per cent. It does not
contain Invertase, and consequently is incapable of fer-
menting Cane Sugar. Amthor,^ who has also investigated
this ferment, agrees with Hansen as to the alcohol produc-
tion in worts, and adduces evidence as to its fermenting
dextrose more easily than Maltose.
Observed by Reess in fruit juices in a state of fermenta-
tion. Cells about 5 \JL long, by 2*5 /* in width at the larger
end ; it multiplies by budding and sporulation. Reess's
form of this ferment, slightly reduced, is shown in the left
half disc, Plate V., Fig. 5.
We have on a few occasions seen a ferment in English
beers, accompanying a cloudy fret, that we believe to be
S. Exiguus ; also in one or two samples of bottled pale ale.
Plate III., Fig. 4, right hand half disc, represents the forms
observed. The marked difference in size between our
form and Reess's may be due to conditions attending the
growth. It probably excites only a feeble fermentation in
* Zeits. f. Physiol. Chemie, 12, 558.
Alcoholic Ferments of the English Process. 53
Beer-wort. The cloudiness in the ales spoken of lasted a
very long time, accompanied by marked flatness.
Most Brewers are familiar with the white greasy film
that this organism develops on Beer that is spilt about, or
left exposed to the air in shallow vessels, as also with its
appearance round the taps and shives of casks. In this
capacity it is acting as an aerobian ferment, absorbing
oxygen, and simultaneously destroying the alcohol of the
beer, forming from it Carbonic acid gas and water. Its
growth under these conditions is very rapid : Engel implies
that in 48 hours, one cell may produce 35,000. Plate V.,
Fig. 6, left half disc, shows the aerobian form. Its dimen-
sions are very variable, depending greatly on the conditions
attending growth. If these are unfavourable the cells may
be as small as S. Ellipsoideus, whilst on the other hand in
a very free growth they may be quite twice as large. The
average length of those depicted is about 9 /j.
Pasteur showed, in addition to other points connected
with Saccharomyces Mycoderma or Mycoderma Vini, that
when submerged in a fermentable liquid it acts as a slow
ferment, forming alcohol and Carbonic acid gas, the cells
meanwhile undergoing some alteration in appearance,
[Plate V., Fig. 6, right half disc] the filled out brighter
cells being the active form. Where ales are badly bottled,
and left standing upright with leaky corks, a film of
Mycoderma Vini not unfrequently forms on the surface,
and may do this to a limited extent where the corks are
fairly sound. This film on being submerged can, if the
leakage stops, act as an alcoholic ferment. If the leakage
goes on, the Mycoderma Vini falls in flakes through the
liquid, which becomes utterly spoilt.
Ordinary well-bottled ales not unfrequently show some
54 Alcoholic Ferments of the English Process.
cells of this ferment amongst the deposit, and there is no
particular reason for believing that a small quantity does
any harm. The residues of forced beers show it in the
Casks returned to the Brewer only partially filled with
ale, frequently include a copious growth of Mycoderma
Vini, resulting from exposure to the air. Owing to the
peculiar clinging nature of the film, it becomes a question
whether ordinary cleansing perfectly effects its removal.
Reverting to the fact that the usual habit of Mycoderma
Vini is that of an aerobian ferment, that is to say, it is
favoured most by free contact with air, and that growth
apart from air is the abnormal state ; it does not seem out
of place hene, to remark, that Pasteur has shown* that some
of the true alcoholic ferments may pass from the anaerobic
state of existence to the aerobic. This is often seen to
occur in experimental fermentations in flasks, etc. After
the primary fermentation is over the liquid being pre-
served in a state of quiescence a film forms on the
surface of the. liquid and the sides of the flask, consisting
of cells of -Saccharomyces formed in free contact with air.
On submerging these cells in a fresh nutrient solution, the
phenomena of active fermentation are reproduced.
Having on more than one occasion obtained evidence of
the presence of the spores of this mould in samples of
pitching yeast, we may here briefly allude to the fact that
the mould may give rise to a well-defined ferment form
[Plate VIII., Fig. 4], producing cells of very variable size.
We have never seen one of the larger cells of Mucor
Racemosus in either yeast or beer, but as it is a somewhat
feeble alcoholic ferment, it would be at such a disadvantage
* " Studies on Fermentation," trans. Faulkner and Robb, p. 208.
J C.Wright. del.
Beer Deposit (Wild Yeasts &c.)
West. Ne.wrr.ar, Ji Co
Alcoholic Ferments of the English Process. 55
in an ordinary fermentation, that its more luxuriant forms
would probably not be produced.
RACKING BEER SEDIMENTS.
Having, as we hope, dealt in a sufficient manner with
the forms of Saccharomyces that are, or may be, encoun-
tered in the Brewing process as carried out in Great
Britain ; some considerations on the deposits thrown down
by samples of beer taken at racking will bring this
chapter to a fitting conclusion. In the first place, as to
the mode of obtaining average samples of the " Brewing."
If not taken from a racking square or flattening vessel, but
from union or cleansing casks, they should be gathered
from more than one vessel, by boring, or from a little
sample tap half way up the cask heading ; care being taken
as to the exclusion of extraneous matters, e.g. borings, in
the sample. A thoroughly clean 8 10 oz. stoppered glass
bottle is a proper receptacle, and if not perfectly dry, it
may be rinsed out with a little of the beer that is being
sampled. After standing some 10 or 12 hours, a more or
less complete deposition of the suspended matters will have
occurred. Some of this sediment may be removed by a
glass pipette, or the ale may be run off, leaving a minute
quantity of liquid, which by shaking, may be caused to
incorporate the whole sediment. With either mode of
treatment, a drop is placed on a slide, a cover glass put on,
and a microscopic examination made. Plate VI., Fig. i,
shows a normal clean deposit, the extraneous matters being
minute spherules, or agglomerations of hop resin, with a
crystal or two of oxalate of lime. It may be mentioned
that spherules or globules of resinous matter and hop oil,
not unfrequently exhibit a peculiar class of movement quite
distinct from the vital movements of certain organisms.
The student may easily produce a good example of this
56 Alcoholic Ferments of the English Process.
phenomenon by mixing a little gamboge with water and
examining it under the microscope ; minute particles and
globules exhibiting much activity will be seen. This is
known as the Brownian movement. Another point worthy
of consideration is, that there is occasionally a possibility
of mistaking globules of hop resin for small forms of
Saccharomyces and other organisms. Where there is a
doubt, it may be dispersed by treating some of the Beer
sediment with a little weak Ammonia or other slightly
alkaline liquid, when the resin dissolves ; generally clearing
the field to such an extent that a further examination
indicates very precisely what organisms or forms are really
present. Plate VI., Fig. 2, represents a sediment resulting
from a beer brewed with very impure yeast, in respect to
wild forms : some of the ordinary extraneous matters are
also given. In the case of isolated cells, it is by no
means easy to refer them to their precise species of
Saccharomycetes, though sometimes there is little doubt
as to what they are. In the present case [Plate VI.,
Fig. 2] S. Pastorianus and Caseous Yeast No. 2, may be
recognized, but the usual uncertainty attends the other
RECENT RESEARCHES IN CONNECTION WITH LAGER-BEER
two chief varieties of alcoholic ferments included
. -L under the title Saccharomyces Cerevisiae are, as
most of our readers will be aware : first, the ferment which
may be considered common to the Breweries of the United
Kingdom, which has a general tendency to collect at the
surface of the fermenting liquid as attenuation becomes
advanced : secondly, the alcoholic ferment in general use
in pursuance of the German method, the general tendency
of the yeast in this case being to settle at the bottom of
the fermenting vessels. The following terms denoting the
difference of behaviour of the two ferments, are in some-
what general acceptance, viz., Surface and Sedimentary,
High and Low, Top and Bottom, yeast.
The differences exhibited on a microscopical examination
of English and German liquid yeasts are not so strongly
marked as might be imagined. Plate VII., Fig. i, shows
Lager-beer yeast according to two different authorities :
it exhibits very much the same rounded and oval forms,
of about the same average diameter as the English yeast ;
the vacuoles are sometimes more plainly visible than in
this last, and there is doubtless a greater tendency for
58 Recent Researches in connection with Lager-Beer Yeast.
the newly-formed cells to remain attached to the parent
cell, owing to the placid nature of the fermentation ; thus
causing a more frequent occurrence of cells in pairs, or
groups of cells containing a greater number than two.
We may say, however, that several samples of Lager-beer
yeast that we have examined, show the cells in a fairly
A few words in connection with the Continental Lager-
beer process will, we think, not be out of place. Con-
siderably less trouble appears to be taken in the production
of malt than is the case in this country ; it is grown up
less, 8-9 days on the floors being the average time ; and is
a much shorter time on the kiln ; malt for Bavarian-beer
being dried in from 36-48 hours, whilst a less time suffices
for the malt used for Vienna and Bohemian beer. The
drying temperatures given by Thausing, for Vienna and
Bavarian beer-malt, are somewhat higher than we employ ;
but this may be entirely a matter dependent on kiln construc-
tion. A very full extract is obtained in the mash-tub on
the decoction system ; and the worts are somewhat lightly
hopped, but an excellent quality of hop is usually
employed, and added to the copper in two portions, the first
being boiled from 1^-2 hours, the second f-i hour. For
the lighter kind of running ales (Schank-bier), about 6 Ibs.
of hops per quarter of malt are used, whilst for store or
Lager-beer 8 or 9 Ibs. would be the quantity. The worts
of specific gravity averaging about 1052-5 are cooled to a
low temperature 4O-5o F. according to the class of ale
required ; the fermentation lasting from 8-14 days. A very
moderate head is formed, appearing first as a slight froth,
then taking on a crinkled appearance ; in fact, making
allowances for the sluggish nature of the fermentation, the
surface changes bear comparison with those we are familiar
with in this country. A small amount of yeast is contained
in the head, but it eventually settles almost completely.
Pel I i eld at 6- 15 C.
Pet Itch of 20-34C.
PG//IC/B. Old culture.
Growth of S. CersuisiaQ I (offer Hans en)
Reduced from 1000 to JOO diameters.
Recent Researches in connection with Lager- Beer Yeast. 59
During fermentation, the temperature rises a degree or two.
Lager-beer is usually racked into somewhat capacious
casks, of varying size, holding on an average some 25
barrels, and stored in a cellar whose temperature is kept
as near as possible to the freezing point, for three months.
The process of Pasteurization or sterilization of bottled
beer, is somewhat extensively employed in Germany ; it
consists in submitting the beer in bottle to a temperature
of about 130 F. for half-an-hour or so, thus securing
practical immunity from change. The process is obviously
not applicable to English beers, which require living fer-
ments to ensure the necessary secondary fermentation :
whereas the German beers being bottled at a low tempera-
ture, contain an amount of Carbonic Acid gas, which on
expansion by rise of temperature, ensures the requisite
Low yeast seems to exhibit activity throughout a some-
what wide range of temperature ; its action can go on as
low as the freezing point, and on the other hand it may be,
and is, frequently employed for bakers' purposes, exhibit-
ing a degree of activity in this respect, far superior to most
English yeast. As mentioned under Caseous ferments
(page 48), we have ourselves obtained the phenomenon of
surface fermentation, from a low yeast having a fairly
powerful action at 60 70 F., and capable even of fer-
menting at 80 F. It constituted also an excellent bakers'
The question naturally arises from such considerations
as these, as to what is the nature of the connection, if any,
between "low" and "high" yeast. Pasteur,* after first
expressing the view that the different types of Brewing
yeast might be modifications derived from some original
type of ferment the existing differences in action having
become hereditary comes eventually to the conclusion
* " Studies on Fermentation," trans. Faulkner and Robb, pp. 187191, et seq.
60 Recent Researches in connection with Lager -Beer Yeast.
that "high" yeast is a distinct species; but he herewith
proceeds to describe mere than one species of high yeast,
and was probably at no time working with pure cultivations
even of these. Reess* expresses his opinion in the follow-
ing manner : Striking as may be the differences between
the vegetation of " low " and " high " yeast, it does not allow
of their division into distinct species. " Low " yeast can
grow and bud at temperatures 9 18 F. higher than
those employed in "low" fermentation, but the out-put of
yeast is small, and in a single experiment the appear-
ances of high yeast are not arrived at. On the other
hand, S. Cerevisiae of " high " ale-fermentation, set at
40 43 F., vegetated after six days, in typical "low"
yeast forms : hence Reess considers that the "high" and
" low " ferments may be modifications of the same species.
Our own view in connection with the matter is this :
That where the morphological and chemical functions of
different ferments are not very different, and temperature
most favourable to action is the chief variable, it is
more than probable that by gradual acclimatisation, the
ferments could be brought to exercise their action at the
same range of temperature. Some recent work of Dr.
Dallingert on Monads, seems to us by analogy to favour
this view. During seven years he applied to a certain
kind of low organisms termed Monads, a range of tem-
perature commencing at 60 F., and cautiously raised,
or held as the occasion required, month by month
till 158 F. was attained, the organisms still living and
multiplying : a temperature far below this being imme-
diately fatal to unacclimatised organisms. An accident
unfortunately terminated the experiment at the temperature
last named. It was calculated that at least half-a-million
generations must have been produced. From our point
* Untersuchungen liber die alcoholgahrungspilze. Dr. Max Reess, p. 8.
f Journal Royal Mic. Society, Feb. 9, 1887.
Recent Researches in connection with Lager- Beer Yeast. 61
of view then, it seems possible that existing forms in
"low" yeast have their specific representatives in "high"
yeast, or vice versa, and that the various kinds of Sac-
charomyces may be modified or educated into carrying on
their fermentative action at essentially different ranges of
The foregoing argumentative matter leads us by a natural
gradation, to a consideration of the efforts that have been
made to select and cultivate particular species and varieties
of Saccharomyces. Hansen has been the chief investigator
here, and his work, besides being of much scientific
interest, has been productive of practical issues of much
importance to the Continental Brewer, and as some think
may eventually have its effect upon the English process.
Until comparatively recent years Lager-Beer yeast seems
to have been of pretty much the same heterogeneous
character as British yeast, and like it may be considered
to have contained a preponderance of some particular
species of yeast which had survived amidst unfavourable
conditions, and was best calculated to carry out a fermenta-
tion at the low temperatures employed, and hold its own
against the foreign ferments present ; these last however,
would as m this country gain the upper hand now and
then, and cause serious trouble, such as frets in the finished
ale, persistent cloudiness and unpleasant flavours, besides
the incursion of Bacteria and, as a possible accompaniment,
the complete spoiling of the ales. Now, although Pasteur
had more than hinted that foreign or wild yeasts might be
a source of trouble, Hansen was one of the first to perceive
that practical immunity of yeast and beer from Bacteria did
not by any means imply freedom from abnormal secondary
fermentation, and to him belongs the credit of having
by a succession of ingenious researches, elaborated a prac-
tical method for the differentiation and cultivation of species
or varieties of yeast that are distinctly favourable in their
62 Recent Researches in connection with Lager-Beer Yeast.
action, as compared with those kinds that are distinctly the
reverse. We purpose somewhat generally reviewing the
steps by which Hansen arrived at the present standpoint.
In 1879* he published the first communication on the
organisms which at different periods of the year are found
in the air at Carlsberg and its environs, the said organisms
being susceptible of development in Beer wort. The
results accruing from this research we have detailed in
connection with air (Chap. X.) ; for our present purposes
it is sufficient to remark that a great variety of Saccharo-
mycetes were encountered, with organisms of other
classes. Some of these organisms were studied separately,
and amongst them Saccharomyces Apiculatus.t We have
already alluded to the main facts elicited in this research,
in the prosecution of which new methods and apparatus
were devised for the cultivation of the organism in a state
In 1882 a further communication \ appeared, dealing
with the organisms found in the air of Carlsberg and its
environs ; the method of air testing by exposure of flasks
of previously sterilized beer-wort to the local infecting
influences, being applied to a determination of the per-
centage of organisms in different parts of the Old Carlsberg
Brewery ; this percentage being found to vary very much
according to the particular location. Certain occurrences
in the Carlsberg and other Danish breweries induced
Hansen to experiment with a variety of S. Pastorianus,
obtained from some of these air sown cultivations ; and on
carrying out experimental fermentations of Beer-wort with
it, he found that the beer so produced had always a par-
ticular odour and a disagreeable bitter taste ; brewings
carried on side by side with S. Cerevisise giving a normal
* Meddelelser fra Carlsberg Laboratoriet. Andet Hefte, 1879.
+ Meddelelser fra Carlsberg Laboratoriet. Tredie Hefte, 1881.
% Resume du Compte Rendu des travaux du Laboratoire de Carlsberg. i er vol.,
4 e livraison.
Recent Researches in connection with Lager- Beer Yeast. 63
beer from the same wort. Hansen contrasted this state of
things with what had occurred in practice in the Danish
breweries, and concluded that this form of S. Pastorianus
was a fruitful source of trouble, and as associated with a
variety of S. Ellipsoideus was the source in the case of the
Tuborg and Alt Carlsberg breweries. From the impure
yeast of Alt Carlsberg four kinds of Saccharomyces were
separated, of which only one, now known as Carlsberg low
yeast No. i, gave a normal beer; of the other forms, that
designated S. Pastorianus I. was the chief cause of mischief.*
The value of the results was at once apparent, and in 1884
yeast selection on a practical scale was an accomplished
fact. Returning now to some of the detail by which this
end was attained. The first thing to be done was to
secure pure cultivations from single cells. Nageli, Lister,
Klebs and Koch had paved the way to this, by arriving at
an estimate of the number of Bacteria contained in a given
portion of an infected liquid, and then diluting it to the
extent necessary to give one individual in a definite small
volume ; but the difficulty was to ascertain beyond a doubt,
that the observed growth following the infection, proceeded
from one germ alone. Hansen working with yeast was
able to settle this point, from the fact of the cells that
were sown, adhering to the walls of the culture flasks and
forming a spot or colony as the growth proceeded.
Koch devised a method of dilution and subsequent
cultivation in nutrient gelatine, which answered well for
both yeast and bacteria, as the colonies formed remained
undisturbed, unless they merged into each other, or a
liquefaction of the gelatine took place. In the meantime
Professor Panum of Copenhagen, had brought into more
general application an instrument known as the Haemati-
meter, for counting the organisms in a given area ; Rasmus
* Untersuchungen aus der Praxis der Gahrungsindustrie. Dr. Emil. Chr. Hansen.
i Heft, p. 12.
64 Recent Researches in connection with Lager-Beer Yeast.
Pedersen applying the same to the counting of yeast
cells more especially.* Hansen subsequently proceeded
to devise a modification of existing culture apparatus
whereby he could determine whether a growth proceeded
from one or several individuals.
We will now proceed to describe processes embracing
the foregoing, first mentioning a method that we have
employed ourselves for calculating the number of cells
present in a given volume of liquid. A drop of ordinary
liquid yeast is stirred into 100 cubic centimetres of sterilized
distilled water, and a portion measured as follows. An
eyepiece micrometer ruled in squares, is fitted to the
Microscope, with an objective that magnifies some 40 50
diameters, rendering the yeast cells just visible. The
relation of the micrometer scale to a Stage micrometer
divided into icoths and icooths inch is ascertained. A
square cover glass is taken ; its sides measured by the
eyepiece micrometer ; and the area calculated. Next the
area of the visible field is computed from its diameter as
measured by the micrometer scale. The area of the field
divided into the area of the cover glass gives the number
of fields that could be provided by the cover glass, j* A
loop say -| inch diameter, is made at the end of a piece
of ordinary platinum wire, and then bent at right angles to
the shank, so that when dipped into any liquid, a drop of
such size is taken up as will, when placed on a slip and the
cover glass put on, fill up all the space under this last.
The drop having been previously weighed by hanging the
wire to the hook of a chemical balance, we have now all
the data necessary to calculate the number of cells in a
given volume of liquid, and dilution can be carried out
so that i cc. contains i cell or any desired number : for
instance, supposing dilution were first carried out till only
* Meddelser fra Carlsberg Laboratoriet. Forste Hefte, 1878.
f This may be preserved after valuation.
Recent Researches in connection with Lager- Beer Yeast. 65
one cell per square of the micrometer scale had been first
exhibited, the next dilution could be arranged to give one
cell per field, and a last dilution, regulated by the number
of fields in the cover glass, would give one cell per drop.
To ensure the more complete dispersion of the yeast in
water, and to obviate froth, Hansen adds a trace of dilute
Sulphuric acid (i : 10). He also uses a capillary tube to
provide a drop of known volume, and the Haematimeter
for counting ; this latter consists of a shallow glass cell,
made by cutting a circle out of a cover glass, and then
cementing the remainder to a glass slip. The drop fills up
the space of the shallow cell when a cover glass is put on.
The portion of the glass slip forming the bottom of the
shallow cell, may be divided by ruling on some known scale ;
or the cover glass is ruled. The cell is o'i millimetre
deep, and the ruled squares usually 0*0025 mm. square.
The cubical capacity of each small square then equals
.00025 cc. Hansen recommends that 48 to 64 squares
be counted, in order to arrive at an average of cells per
square, or per cubic centimetre.
A suitable dilution having been
obtained, some nutrient liquid or
medium may now be infected.
First, as an example of a liquid :
Bitter wort, as collected bright from
ground bags, affords a suitable
nutrient solution for most of the
Saccharomycetes, and quantities
may be collected in Pasteur Flasks
(Fig. 1 8), which are the most con-
venient form of apparatus for such
work. The flask having been two-
thirds filled with wort, is raised to boiling on a sand bath,
steam first issuing from the side tube a, provided with a
piece of caoutchouc tubing, which is then stopped with
Fig. i 8.
66 Recent Researches in connection with Lager-Beer Yeast.
a glass rod. Steam next issues from the long tube, and
this after a short interval is in turn closed with an asbestos
plug. The sterilization should now be complete, and the
contents of the flask may remain for years practically
unchanged. As the flask cools, the air entering is filtered
through the asbestos, and any germs passing it are
deposited on the sides of the tube, which can be re-
sterilized at any time by external application of heat.
The Chamberland flask (Fig. 19) is a convenient form
for some experiments. If it be desired to keep the liquid
sterile in vacuo, the forms shown in Fig. 20 may be
employed ; the tube being plugged with wool or asbestos
can be bent over ; and sealed off by a suitable flame, such as
the blow-pipe, during the drawing in of air after boiling.
The simplest form of culture flask is the conical one
(Fig. 21), in which the liquid is sterilized in the ordinary
way, and a piece of sterilized filter-paper is secured over
the mouth by an india-rubber ring or other means.
The flasks are infected with the desired organisms by
Recent Researches in connection with Lager- Beer Yeast. 67
introducing the necessary portions of liquid rapidly, with
all precautions requisite to ensure sterility of implements
used, and in a room as free as possible from floating
dust. In the flask Fig. 18, the Fi
introduction is made through the
short tube, and the stopper imme-
diately replaced. In Fig. 19, the
ground neck and cap are con-
veniently smeared with a little
vaseline before sterilizing the liquid :
the cap being removed the infect-
ing liquid is introduced. In the
case of Fig. 20, the tube is allowed to dip into the
infecting liquid, and the point being broken off under it,
the vacuum causes an in-rush of liquid which may be
controlled as desired. With Fig. 21, it is simply a matter
of taking off and replacing the old or a fresh paper
covering. In each case the flask after inoculation, is
submitted to a favourable temperature in an incubator or
warm chamber. Where yeast is sown, it falls to the bottom
of the flask and fermentation starts, the points of growth
being noted : each speck appearing indicates a colony.
Where the object is to procure only one colony in a flask,
it is usually desirable to set a certain number with, say
i cc. of a liquid containing an average of \ a cell, that
is, i cell to every 2 cc. Let us suppose the colony
resulting from the growth of a single cell to have been
obtained in a Pasteur flask, and that a larger quantity of
pure yeast from the same "store" is required. Most
of the beer is run off through the small side tube ; the
remainder is shaken up with the yeast ; and the whole
removed by connecting the short tube by a caoutchouc
tube, with the orifice of some large tinned copper vessel
holding some gallons of wort, which has been sterilized in
it by boiling and subsequently cooled. Here sufficient
68 Recent Researches in connection with Lager- Beer Yeast.
yeast is produced to set a much larger fermentation, and
so eventually enough is obtained to pitch a square. For
further detail we must refer our readers to Hansen's own
communications,* or translations and abstracts of them in
the Brewing Journals.
Hansen adopted at a certain stage in his experiments, a
solid medium for the initial cultivation of the selected cells,
consisting of a mixture of hopped wort and gelatine. It was
thus made possible to trace the development of the single
cells under the microscope. The method is as follows :
A specimen of the yeast is largely diluted with water in a
Chamberland flask ; drops of this are further diluted with
hopped wort and gelatine wort of Sp. gr. 1058, and
5 10% of gelatine, filtered bright, or fined and filtered
contained in test-tubes in which it has been sterilized and
cooled to 70 75 F. Complete mixture is effected, and
a drop of the gelatine wort, now containing yeast, is
examined microscopically, and should show only a cell or
two to a field. Dilution to any desired extent may now
be carried out ; a drop being finally withdrawn by a
sterilized glass rod, and spread on the under surface of a
thin cover-glass, which is placed on the ring of a Bottcher
or Ranvier moist chamber. f [Figs. 22 and 23.]
The Bottcher chamber [Fig. 22] consists of a glass cell
formed by cementing a ring (c) to a slide ; water is placed
in the bottom (d\ and the position of the drop of gelatine
is at b, on the under side of the cover-glass a. The
* Untersuchungen aus der Praxis der Gahrungsindustrie. Dr. Emil Chr. Hansen.
\ These moist chambers appear to us to be a modification of Van Tieghem and
Lemonnier's cell for examination of moulds.
Compare "Etudes sur la Biere," Pasteur, p. 153 ; trans, p. 155.
Recent Researches in connection witk Lager- Beer Yeast. 69
Ranvier chamber (Fig. 23) is a modification of the fore-
going, the water receptacle being an annular groove a, a,
ground out from a slip, the portion enclosed c having its
height reduced to afford space for the drop of gelatine
enclosed between the cover-glass b, and c ; the edges of
the cover-glass projecting beyond the circular groove.
Vaseline may be smeared on the surfaces which come
in contact, so as to secure air-tight connections. In either
case one or two cells are picked out, and their position
marked by a diamond on the cover-glass ; the apparatus
is then put in an incubator at 80 90 F., and left for
a day or two before re-examination. The specks of yeast
may be taken up by a short piece of Platinum wire, and
the wire dropped into sterilized hopped wort of Sp. g. 1058,
contained in Pasteur flasks." The growth being known to
proceed from a single cell, the required conditions are
fulfilled. Through the whole of Hansen's work there is a
pervading idea that the shape, size, and appearance of the
cells did not in themselves suffice to confer a distinct
individuality as regards species or variety ; for one and the
same kind of Saccharomyces was found capable of exhibit-
ing a variety of forms, corresponding to changes in the
* Resume du Compte Rendu des Travaux du Laboratoire de Carlsberg. 2me vol.,
4me liv., 1886.
/o Recent Researches in connection with Lager-Beer Yeast.
conditions attending development. As an example: a
'Mow" yeast growing with difficulty at 80 F. may give
long branching cells, whilst at 45 50 F. it would give the
well-known low yeast forms. On this was based a test that
Hansen employed for low yeast (and by which he identified
several species or varieties that had specific actions in the
Brewing process, that we shall speak of later on), namely,
to first examine microscopically the sedimentary form
produced at normal temperature, and then to set the yeast
afresh, and allow it to develop in wort at 78 80 F.
These purely microscopical investigations were followed
by observation of peculiarities in the mode of growth,
and notably the conditions under which Ascospores were
formed;* and from the variations shown in this latter
respect under like conditions of temperature, etc., Hansen
collected further means of identification of the differentiated
S. Cerevisise I.
S. Pastorianus I.
S. Ellipsoideus I.
We have already in Chap. III., spoken of the peculiar
mode of reproduction by ascospores, and the way in which
the phenomenon is obtained. Hansen employed sterilized
blocks of plaster of Paris, on which the yeast was poured,
and which were then put into shallow glass dishes half
filled with water, and covered up. For ordinary ascospore
formation a temperature of 60 F. suffices. It was found
that sporulation proceeded very slowly at low temperatures,
becoming more rapid as the temperature rose, till a point
was reached where the development was again restrained,
and finally ceased entirely. The lowest temperature for the
* Resume du Compte Rendu des Travaux du Laboratoire de Carlsberg. 2me vol.,
2me liv., 1883.
Recent Researches in connection with Lager-Beer Yeast. 71
six kinds of yeast first treated was 33 F. or '5 C. ; the
highest limit, 99-5 F. or 37-5 C. Between these limits
there were characteristic landmarks for the different kinds
of yeast, which enabled a separation to be made. The
results are concisely and conveniently expressed in the
following table, taken from a paper read by Dr. G. H.
Morris in 1887.* The equivalents of the Centigrade
temperatures in Fahrenheit degrees have been added.
* " The pure cultivation of Micro-organisms, with special reference to yeast."
Journal of the Society of Chemical Industry, Feb. 28th, 1887.
72 Recent Researches in connection with Lager-Beer Yeast.
It will be noticed that the maximum and minimum
temperatures for the different species, are in themselves
different ; as also the limits of temperature within which the
ascospore formation takes place in the species examined.
The differences are the most marked at the lower tem-
Holm and Poulsen* using the foregoing methods have
succeeded in detecting with certainty the presence of ^ of
wild yeast in a sample of pitching yeast ; this is of the
more interest from the fact that Hansen had previously
found that a mixture of S. Pastorianus III. and S. Ellip-
soideus II. which present in quantity may cause turbidity
in beer does not do so when in the proportion of ^ of
the pitching yeast. The method possesses the advantage
of being moderately quick, for in the above-mentioned
cases a cultivation at 25 C. (77 F.) would give a plain
indication after 40 hours ; the wild yeasts sporulating
The problem of differentiating Brewery yeast has been
further attacked by Hansen apparently with success
by noting the conditions under which films or pellicles of
Saccharomyces are formed on the surface of fermentable
liquids ; the said films or pellicles appearing to us to be
pretty much the same thing as Pasteur's aerobian fer-
ments, t This phenomenon is, as we know, not confined
to Saccharomyces, but the films of the alcoholic ferments
differ in appearance from those of Mycoderma Vini, Bac-
terium Aceti, etc. The films form generally towards the
close of flask fermentations ; small islets of yeast being
carried to the surface collect, and develop a greyish yellow
slimy film, which if partly shaken down renews itself. A
free, quiet liquid surface, with direct entry of filtered air,
* Resume de Compte-Rendu des Travaux du Laboratoire de Carlsberg. 2me Vol.,
f " Studies on Fermentation," trans, by Faulkner and Robb, p. 205, el seq.
Recent Researches in connection with Lager- Beer Yeast. 73
is essential to the growth. The assay flask covered with
a filter paper answers well. During the growth the colour
of the wort becomes reduced to a light yellow.
The points Hansen set himself to determine were :
1. Temperature at which the film formed.
2. Time elapsing before the appearance of the film
at different temperatures.
3. Microscopical appearance at different temperatures.
Cells of old films show striking varieties of form. Young
films of S. Cerev. I., S. Past. II., and S. Ellips. II., show
no mycelial or branching colonies ; these last are, on the
contrary, found with S. Pastorianus I. and III. and S.
At high temperatures only S. Cerev. I. and S. Ellips. II.
appear to vary from the others, but at 13 15 C.
(55-4 59 F.), with young films, it is very different;
for instance, S. Past. II. and III., which are upper or
high ferments whose cells in ordinary sowings look the
same give quite a different vegetation ; and an equally
striking difference obtains between S. Ellips. I. and II. :
at this temperature then it is only a matter of difficulty to
distinguish between S. Past. I. and II., and here the
ascospore formation helps, as also the circumstance that in
flask fermentation at ordinary temperatures, one is a " high "
and the other a " low " yeast.
As a typical example of these pellicle growths we give on
Plate VII., Fig. 2, the appearances exhibited by S. Cere-
visiae I., a ferment separated from a sample of Edinburgh
yeast. A reduction to ordinary magnification has been
made for purposes of general convenience, and to permit
of comparison with Fig. i representing Lager-Beer yeast.
The following table, taken from Dr. J. H. Morris's paper*
already quoted, gives the facts connected with the film
formation in a comprehensive manner.
* J. Soc. Chem. Ind. Feb. 28, 1887.
74 Recent Researches in connection with Lager-Beer Yeast.
Fah 1 .
Gen 4 .
96-8 100 '4
7-1 1 n
42-8 44' 6
35 '6 37'4
In the above table, dys. = days ; mths. = months.
The chief properties of the ferments that have been
spoken of in connection with ascospore and film formation,
are given in the following summary.*
S. Cerevisise I. A u high" yeast obtained from the
pitching yeast of an Edinburgh Brewery, and afterwards
from that of a London Brewery, develops ascospores at
temperatures between 11 C. and 37 C. ; the greater
number of the cells resembling the original yeast ; film
formation at 13 15 C.
S. Pastorianus I. Obtained from air-dust in the neigh-
bourhood of the Carlsberg Brewery, Copenhagen, is a
11 bottom" ferment resembling Pasteur's. f It imparts a
bitter flavour to beer, develops ascospores at temperatures
between 3 C. and 30.5 C. ; film formation at 13 15 C.
S. Pastorianus II. From air-dust. Rather larger than
Pasteur's or Reess's form. Acts mainly as a bottom
ferment. Causes no disease in beer. Develops ascospores
between 3 and 28 C. ; film formation at 13 15 C.
S. Pastorianus III. From a low-fermentation beer
* Derived mainly from " Micro-organismen der Gahrungsindustrie " (A. Jorgensen).
t Etudes sur la Biere. Trans. " Studies on Fermentation," Faulkner and Robb, Plate XI.
Recent Researches in connection with Lager-Beer Yeast. 75
produced in Copenhagen, attacked by yeast turbidity (S.
Ellips. II. present at the same time). Develops ascospores
between 8.5 and 28 C. ; film formation at 13 15 C.
S. Ellipsoideus I. Obtained from the surface of ripe
grapes from the Vosges. Effects on beer not yet investi-
gated. Resembles Pasteur's and Reess's form. Develops
ascospores between 7.5 and 31.5 C. ; film formation at
i3 15 C.
S. Ellipsoideus II. Associated with yeast turbidity
in beer. Develops ascospores at temperatures between
8 and 34 C. Film formation at 13 15 C. Resembles
the ordinary form, S. Ellips. I., in a marked degree.
With the exception of S. Cerevisiae I., which constituted
the larger proportion in some samples of English yeast,
the above-mentioned forms are to be regarded as wild
yeasts, and as contaminating influences in relation to normal
healthy yeast, for their presence in appreciable quantity
may render an otherwise normal brewery yeast incapable of
producing a beer of good flavour and keeping properties.
Contamination with wild yeasts may be produced by the
dust of the air during summer and autumn, and may
originate from other sources.
And now as to some of the practical results of yeast
selection. In the first place, two varieties of S. Cerevisiae
have been separated from " low " yeast, and are employed
in the Carlsberg and other breweries, being known respec-
tively as No. i and No. 2 Carlsberg yeasts.
No. i obtained from the yeast which had been in use
in the Carlsberg Brewery for many years, and which was
originally brought from Munich gives a beer of much
stability, somewhat thin on the palate, and containing less
Carbonic Acid gas than that from No. 2. The beer clears
very slowly in the Lager cellar, but when bright, should
remain so for at least three weeks after bottling, for which
last it is well adapted.
76 Recent Researches in connection with Lager- Beer Yeast.
No. 2 isolated from Hamburg yeast, and later from
that of other places gives a nice flavoured beer of much
palate fulness, which contains more Carbonic Acid gas
than No. i. The Beer is not adapted for bottling, having
keeping properties inferior to that from No. i.
As an indication of the scale on which pure cultivation
has been carried out, it may be mentioned that Hansen,
starting from a single cell, produced in a few weeks the
whole bulk of yeast (5,500 Ibs.) employed in the Alt
Carlsberg Brewery. For some four or five years selected
yeast has been in continual use in the Carlsberg Breweries,
being periodically produced by an inter-dependent process.
The two Carlsberg Breweries together turn out some
400,000 hectolities of beer (say 244,000 Barrels) per annum.
Selected yeast is used besides, in some of the breweries
of other countries, and seems to give satisfaction. In
addition, some few breweries are working with yeast
selected by Hansen's method from their own original
Under favourable conditions, the pure selected yeast
does not soon deteriorate ; for instance, in Alt Carlsberg
the No. i yeast has been kept pure for 6 to 8 months,
and the No. 2 yeast, 2 to 4 months, even with free exposure
to air of the worts on the cooler.
Where yeast is to be examined for wild forms, Hansen
recommends that the samples be taken at the end of the
primary fermentation : if for the selection of cells of the
normal ferment, the samples should be taken at the
commencement of fermentation.
A point of some interest in connection with Hansen's
work, is the evidence he adduces as to the persistency of
form, in the progeny of differently shaped cells of one and
the same species or variety of yeast ; spherical cells
producing spherical cells, and oval cells those of an oval
form ; though, with long continued cultivation, a tendency
Recent Researches in connection with Lager-Beer Yeast. 77
to produce one type of cell becomes more and more
marked, till finally, all the cells approximate to the same
Certain species of Saccharomyces, namely, S. Exiguus,
S. Minor, and Reess's S. Conglomerate the latter of
which does not seem to be associated at all with beers
have not as yet been put to the test of pure cultivation.
In addition to the Alcoholic ferments that have been
already mentioned in this and the foregoing chapter, there
remain a few of rarer occurrence, of which we need only
mention in the briefest manner.
Saccharomyces Marxianus (Hansen). Forms small cells
like S. Ellipsoideus and S. Exiguus, also very irregular
forms. Does not yield ascospores readily. Gives only a
feeble fermentation in beer-wort, being unable to ferment
Saccharomyces Membransefaciens ( Hansen). Produces a
clear grey pellicle on beer-wort. Forms oval or elongated
empty-looking cells. Yields spores abundantly. It does
not ferment beer-wort. Appears to be inactive with most
sugars ; and is unable to invert Cane Sugar. It liquefies
gelatine very readily. Hansen appears to class it as a
Saccharomyces on account of the spore formation, but,
in face of the evidence he adduces, it would seem to be
rather straining the title.
Excellent as is the whole of Hansen's work, and of
unquestionable physiological interest and importance, it
still remains an open question as to whether a degree of
purity of Lager-beer yeast consistent with the requirements
of practice, could not have been secured by other means
than single-cell selection ; such for instance, as attention to
the plasmatic conditions most favourable to the action of
one species of yeast. M. Velten, of Marseilles, one of
Hansen's chief antagonists, evidently has views of this
kind in connection with the matter. He gives the prefer-
78 Recent Researches in connection with Lager- Beer Yeast.
ence to what may be called Pasteur's normal yeast, that is,
a bacteria-free yeast containing a preponderance of a
desired species, and whose foreign or wild yeast forms are
essential to a proper secondary fermentation. Our own
experience of the persistence of certain types of yeast in
this kingdom, such as London, Edinburgh, Yorkshire Stone
Square, and Burton yeasts, leads us to attach no little
importance to Velten's views ; and it seems to us that the
case may be stated as follows : From Velten's point of
view the conditions of the process should be adapted to
secure the production of a yeast of uniform type, starting
presumably, with a yeast that has before given satisfactory
results. Hansen's contention is practically the converse
of this viz., that a yeast must be selected to suit the
Hansen himself admits that the pure selected yeast will
not do everything, and putting aside for the moment any
consideration of its adaptability to English beers, there are
some cases where pure yeast would manifestly not produce
the required result. We speak of some of the Belgian
breweries in which beers are still produced by spontaneous
The methods of brewing pursued in the United King-
dom are certainly such as to encourage the development of
more than one kind of Saccharomyces, and we know
that our beers are open to defects similar to those that
Hansen encountered. Granting that a selection could be
made of a typical cell suited to each mode of fermentation
carried out in this country, and which would give the
desired flavour and normal secondary fermentation, the
present conditions of the process would, we think, neces-
sitate a frequent production de novo of the typical yeast
to replace the degenerated ferment. Experiments on an
industrial scale with different species of pure yeast have
been carried out at Burton-on-Trent by H. T, Brown and
Recent Researches in connection with Lager- Beer Yeast. 79
G. H. Morris, and it is their expressed opinion that many
difficulties have yet to be surmounted before the English
Brewer can place the same reliance on pure cultivated
yeast as his Continental confrere is able to do, but that,
when these difficulties have been surmounted, pure yeast
culture in a more or less modified form, will play a very
important part in our English Breweries.*
* H. T. Brown's Introduction to "The Micro-organism of Fermentation." A. Jb'rgensen.
Edited from the German by G. H. Morris.
i G. H. Morris, Soc. Chem. Ind., 1887, p. 122, and Brewing Trade Review, 1888, page
387. "Alcoholic Ferments, etc."
THE MOULDS OR MICROSCOPIC FUNGI.
OWING to the great variety of form exhibited by
Fungi generally, varying as they do from the huge
toadstool and mushroom, to the minutest mould, any
complete classification of even the moulds alone, including
as it would such a vast number of species, would be too
complex a matter to be either interesting or useful from
the Brewing point of view.
The term Mucorini has been applied by Nageli some-
what generally to the Microscopic Fungi, but it is more
often used in classification of the moulds, to denote a certain
group with a habit of growth similar to Mucor Racemosus.
The term Mucedines has also been used somewhat in the
same way, but correctly it has even a more limited meaning.
In comparison with the Saccharomycetes and as we
shall see, with Bacteria, the Moulds occupy a position
of secondary importance as associated with Malting and
Brewing ; still, as having at times a definite influence on
the process, we are warranted in giving this class of
organisms something more than passing notice, and so we
purpose describing them in general terms, and briefly to
sketch the mode of growth of the chief Moulds encountered
by the Maltster and Brewer.
The Moiilds or Microscopic Fungi. 81
Scientifically although containing none of the green
colouring matter, Chlorophyll, common to vegetables the
Moulds are regarded as belonging more especially to the
Vegetable Kingdom, occupying a position between Sac-
charomycetes (the ferments) and Schizomycetes (Bacteria),
but showing a close relationship to these two families at
either end of their scale, e.g., the ferment forms of certain
moulds connecting these last with the Saccharomycetes
proper ; the living spores (Zoospores) of other moulds being
closely allied to Bacteria.
The appearance of Mould on various objects, such as old
boots, stale provisions, etc., etc., is of course a very familiar
occurrence, and it is astonishing what very different objects
seem able to support moulds of some kind. The Maltster
is not unused to its appearance as a bluish-green growth on
germinating Barley ; and other rarer moulds may occasion-
ally be noted on the same medium, distinguished by a black
or red colour. The Brewer consequently has at times to
deal with Malt whose quality has been reduced by mould,
and he may occasionally find some of his Hops deteriorated
by a like cause ; or again, for want of proper care the
wooden vessels of a Brewery may fall into a mouldy state ;
and in the best conducted Breweries a certain percentage
of the cask plant is open to adverse influences from the
Let us now use the Microscope for a preliminary
examination of some mould growth : this is a case
where the examination of the selected mass may be
first carried out under a low magnifying power, say
30 or 40 Diameters, so as to give one a good general
idea of the growth, and also to help one to dissect out
portions for examination under higher powers, say 200 to
300 Diameters. Growths of mould, illuminated by the
Bull's-eye condenser are not unfrequently objects of great
beauty when viewed through the Microscope, as they may
82 The Moulds or Microscopic Fungi.
resemble miniature forests of peculiar and luxuriant vege-
tation ; marvellous networks enclosing brilliant spheres ; or
miniature hills with snow wreaths on their summits and
slopes. If then a specimen of Mould be taken from one of
the sources previously indicated, preferably from some
moist mass, it will be probably found to exhibit the
following characteristics : The portion nearest to the
substance on which the Mould has been thriving, is seen
to consist of interlaced threads or filaments forming what
is called a Mycelium. On breaking this up with the
end of a glass rod or a needle, the filaments or Hyphse are
seen to be tubes, and at certain points in these tubes, thin
dividing walls are perceptible, which are termed Septa.
On examining some of the upper portions of the growth,
it is very probable that numbers of small spherical or
oval bodies will be detected, and if care be exercised
in the manipulation will be found to occupy the posi-
tion in which they were originally formed ; these are
Spores, capable in most cases of giving rise to a fresh
growth of the mould, when falling into a suitable nourishing
stratum ; and it is by the formation of these spores that the
reproduction of the generality of moulds is provided for.
The simplest mode of reproduction witnessed amongst the
moulds, is by the continuous budding and dividing off of
portions of the hyphae, a process more allied to the true
budding of the Saccharomycetes than to mere fission. The
next higher mode is the formation of definite naked spores
on the ends of hyphae, from which they are very easily
detached at maturity. A stage above this last phase
of growth is the production of spores compacted into a
receptacle (Sporangium or Ascus), the walls of which must
be ruptured before the contained spores can escape.
In the case of some moulds, the spores when ripe issue
from a well defined spore-case, and show active movements
caused by vibrating hair-like appendages called Cilia or
The Moulds or Microscopic Fungi. 83
Flagella. Such spores are termed Zoospores or Swarm-
spores. The motion continues for a time, and then the
spores settle down and germinate.
A curious mode of fructification which appears to be
of a sexual order, is not unfrequently exhibited amongst
moulds. Two of the threads or hyphae approach and join
each other, and this conjugation is followed by the develop-
ment of a large spore (Zygospore), capable of giving rise
to the mould-growth afresh.
A remarkable phenomenon occurring in connection with
Mould growth is what is called Alternation of Generation
or Polymorphism ; that is to say, a mould may not always
follow one mode of development retaining its characteristic
appearance, but may instead, go through a cycle of changes,
at certain points in which were the development not
traced ab initio one would believe that a perfectly dif-
ferent species was being viewed. A good example of this
is furnished by the "red-rust" of cereals, termed Puccinia
Graminis, which on a different host the Berberis gives
rise to what was formerly regarded as a distinct growth,
and named Aecidium Berberis. It was found that cereals in
the neighbourhood of shrubs of Berberis were generally
attacked by rust. By various observations and experi-
ments the identity of these two dissimilar forms has been
placed well nigh beyond dispute. We shall have occasion
to make a further allusion to this polymorphism in the case
of another mould.
Now as regards the conditions which favour the pro-
duction of mould : Although of higher organisation than
the Saccharomycetes, the moulds seem able to subsist
on less complex forms of nourishment. Solutions of
mineral compounds, such as the Sulphates of Magnesium,
Copper and Zinc, containing mere traces of impurities, will
occasionally furnish growths of this class of organism ;
whilst substances like Ammonium Acetate and Tartrate,
84 The Moulds or Microscopic Fungi.
especially if they be somewhat acid, will also afford adequate
nourishment. In the case of liquids that are capable of
sustaining Saccharomycetes, these last may develop, fol-
lowed by Bacteria ; and finally Moulds may thrive in the
acid liquid so produced, especially with free exposure to
In fruit preserves and syrupy liquids, where the
percentage of sugar is too high to support Alcoholic fer-
ments, and the amount of Nitrogen perhaps too low
for Bacteria, Moulds may grow unrestrained ; though they
commonly follow Saccharomycetes and Bacteria, owing to
their property of growing in acid liquids, especially fruit
juices ; but here again, the acidity may in some cases, be
so great as to prevent Alcoholic ferments or Bacteria
growing, whilst certain moulds would be quite at home
under the circumstances.
The chief components of Moulds appear to be of the
same nature as those of Saccharomycetes ; the enveloping
membranes consisting of a Carbohydrate resembling
Cellulose and possessing some degree of toughness and
durability ; whilst the contents of the hyphae and spores
are viscid protoplasm.
The large Fungi (Mushrooms, etc.) seem to have some-
what the same chemical composition as yeast.
Very little is known of the substances produced by the
growth of moulds in different media. Whatever they may
be chemically, there is usually some taste or smell resulting
that is objectionable, especially the characteristic mouldy
or musty flavour and smell that so many moulds are capable
of producing ; and even in the few cases that we shall
particularise, where moulds grow in the manner described,
the taste of the resulting fluid is generally peculiar if not
Pasteur showed that certain fungoid growths which
vegetated by using the Oxygen of the air, and which
The Moulds or Microscopic Fiingi. 85
derive from oxidation the heat that they require to enable
them to perform the acts necessary to their nutrition, may
continue to live, though with difficulty, in the absence of
Oxygen : in such cases the forms of their mycelial or
sporic vegetation undergo a change, the plant at the same
time evincing a decided tendency to act as an alcoholic
The only distinct industrial purposes to which mould-
growths are applied, are in connection with this power of
forming Alcoholic ferments. It appears besides, that moulds
may give rise to a species of Diastase, as for instance, in
the preparation of the Japanese " Koji," made from steamed
rice on which a yellow dust the spores of a fungus is
placed, and subsequently allowed to vegetate. " Koji " is
capable of liquefying gelatinized starch, and setting up a
fermentation in it, giving rise to a kind of Beer the
Japanese " Sake." Koji is also used in breadmaking and
as a source of " Soy." The mould giving rise to these
spores is called Eurotium Oryzse.
We purpose now dealing with some selected varieties
of Moulds which are associated with the materials used in
the production of Beer, and to a certain extent, with the
beverage itself; also with one or two moulds that have a
connection with wine. We will take them in order of
complexity, beginning with the simplest.
OIDIUM LACTIS is a mould frequently found on the surface
of milk, but which grows in nearly all substances that
sustain mould-growths generally. It occurs occasionally
on crushed germinating Barley; on " grains;" and notably
on pressed yeast, especially German or foreign baker's-
Hansen found it in sterilized worts that had been
infected by germs from the air in the neighbourhood of the
Carlsberg brewery ; but he states that Beer and wort not
directly sown with this mould are little liable to its
86 The Moulds or Microscopic Fungi.
incursion. The same worker's more recent researches
prove, in contradistinction to other authorities, a uniform
mode of growth on different plasma, and a rapid develop-
ment on a suitable substratum with a favourable temperature.
Its appearance on a liquid is somewhat like that of
Mycoderma Vini, but it is more felted, and whiter-looking.
Its mode of growth is of the simplest kind met with
amongst moulds. Under the Microscope the snow-white
downy coating is seen to consist of a mycelium, the
interlacing threads of which are divided by septa into
varying lengths ; the pieces so marked off on certain hyphae
differentiating into still smaller pieces, which fall away from
each other and reproduce similar lengths and chains of
cells ; the smallest cells constituting the nearest approach
to spores. (See Plate VIII., Fig. i.) The elongation
of the hyphae and differentiation by septa seem to go
on simultaneously, thus resembling the development of
Bacteria. With deficient nourishment there is more
tendency to form definite spores or conidia, which repro-
duce by germination. Submerged in Beer-wort, it appears
to be very sluggish in its action. Hansen gives 30 C.
(86 F.) as the most suitable temperature for the growth
of this mould.
CHALARA MYCODERMA is a mould somewhat resembling
the foregoing in its mode of growth, but with a tendency
to form spherical protuberances in the elongated cells.
Hansen obtained this also from the air in the neigh-
bourhood of the Carlsberg Brewery.
OIDIUM LUPULI is an excellent example of a mould
resembling Oidium lactis in its mode of growth ; it is
occasionally met with on spent hops, on which it forms
a reddish-yellow or salmon-coloured dust, which on
microscopical examination, is found to consist of branching
cells, merging like Mucor Racemosus into spherical cells,
some of which have all the appearance of budding. Many
f-LA I L VUL
Oidium Laciis(Reess& l M& l L)
Pen/oil Hum Glaucum (Maddox)
Mucor Racemosus (Submerged)
Fusarium Harden' J -
J E.WRIGHT. DEL.
BflfAOS 4 SOMS.L/Tt.
The Moulds or Microscopic Fungi. 87
of the spherical cells and the branching pieces display
an orange-pink colour, which seems to permeate the
protoplasm. For a purely aerobian form, the mode of
reproduction is decidedly interesting.
OIDIUM VINI, also called Erysiphe Tuckeri, is of some
little interest, not only from the destruction that it has
caused to the French vines in the last 30 or 40 years, but
chiefly because it seems to have a specific action in the
wine itself, growing submerged, and producing a class of
peculiar flavours that render even some of the best wines
undrinkable ; a marked acidity is also a common accom-
paniment of its growth. On the Vine, the mould grows in
the hyphseal condition, with heads of agglomerated spores.
When occurring in wine its appearance is that of hyphae
broken-up into short cylindrical, curved, or branched pieces.
The best method of preventing wines developing this
and other mould growths, is to sterilize them by Appert's
process, which consists of subjecting the wine for a short
time in closed vessels to a temperature above the boiling
point of water.
PENICILLIUM GLAUCUM, the most widely spread of or-
dinary moulds, is distinguished by its bluish-green colour.
It appears on fruit, food, etc., but to us, its most
interesting occurrence is on germinating barley. It has its
origin as a rule, on the half corns and accidentally crushed
ones ; spreading rapidly under favourable circumstances
to sound corns. Its growth appears to be favoured mainly
by high temperatures on the malting floors ; a large per-
centage of split or damaged corns ; and a decrease in vitality
of the germinating barley, owing chiefly to unfavourable
On examining a mouldy corn under successive powers of
the microscope, a white mycelium is seen on the surface,
from which spring hyphae or threads, bearing tassels of
spores or conidia [Plate VIII., Fig. 2]. These spores are
88 The Moulds or Microscopic Fimgi.
small spherical bodies of a faint bluish-green colour : on
arriving at maturity they fall as an impalpable powder or
dust, which is so light that it is wafted about by the
slightest current of air ; the spore production being at the
same time exceedingly plenteous. As the substance of the
corn provides a most favourable plasma or food, upon
which also the spores germinate almost directly they fall,
the rapid spread of this mould is easily accounted for.
During the growth, Oxygen is absorbed from the air,
and the nutrient matters are resolved in great part, into
Carbonic Anhydride and Water. In absence of Oxygen,
this mould sets up a kind of fermentation ; one of its
actions being, to convert the tannin of certain substances
into gallic acid and sugar. In beer-wort it gives a mycelial
growth, not forming distinct ferment cells, and produces
very small quantities of Alcohol, the liquid taking on a
characteristic mouldy flavour.
Penicillium is one of the moulds that often grow in the
dregs left in Beer casks : the spores of this or probably
other moulds entering the wood, a growth is set up,
which may permeate the material in such a way, that the
removal or destruction of the mould is well-nigh impossible.
If sections of the inner surface of a stinking cask be
examined, they may be found permeated with a mould
mycelium ; but without cultivation it is almost impossible
to tell the precise species of mould that thus occurs ; it
is probably however, one of some two or three species.
There can be but little doubt that the mould growth
has a destructive effect on the wood, rendering it soft
and spongy ; in fact, one knows that timber may be
rendered perfectly rotten by the growth of some fungi.
As the growth of mould is so greatly dependent upon a
supply of Oxygen, it is plainly of importance that casks
should be corked when empty. In the case of Makings,
Oxygen is so essential to the growth of Barley that its
Moulds or Microscopic Fungi. 89
exclusion would in no way help it to resist mould, rather
the reverse in fact ; it must be met by dressing the
barleys ; thorough washing in Cistern ; not allowing the
dust from moving barley to reach the malting floors, and
thorough cleanliness of the floors themselves, secured if
necessary by the use of antiseptics from time to time.
ASPERGILLUS GLAUCUS, next to Penicillium, is about the
most commonly occurring mould on food-stuffs, etc., etc.
Surfaces covered with it, usually present a dusty sage-green
appearance. The spores are produced in great plenty on
a rounded swelling at the extremity of short straight
hyphae which, as is usually the case with moulds, spring
from a mycelium of closely woven colourless hyphae ; later,
the growth not unfrequently enters on an alternation of
form, large spore receptacles (Perithecia) of an orange
yellow colour are formed, containing some Asci and large
lentil-shaped colourless cells (Ascospores) ; this alterna-
tion of form is called Eurotium aspergillus glaucus.
ASPERGILLUS NIGER is morphologically, closely related to
Asp. glaucus, but the growth is quite black. It often
originates on crushed uncooked rice. There does not
appear to be any distinct evidence as to the behaviour of
the former of these moulds when submerged in a fermentable
liquid, but Pasteur has proved that Asp. glaucus produces
a small quantity of Alcohol and Carbonic Anhydride when
so treated, without forming cells like the Saccharomycetes,
but giving branching forms, somewhat resembling Mucor
before the latter develops spherical individual budding
MUCOR RACEMOSUS is a mould of somewhat common
occurrence on fruits and other vegetable substances ; it may
occasionally occur on damp Barley. It forms a mycelium,
from which hyphae arise, bearing on their extremities
sporangia which, when the contained spores arrive at
maturity, break and let loose their contents. Plate VIII.,
9<D The Moulds or Microscopic Fungi.
Fig. 3, exhibits this mould as it occurred on some damp
barley contained in a bot-tle. M. Racemosus is of no little
interest in connection with fermentation, as it gives on
submersion in a fermentable liquid, a very well-defined
ferment form, beginning with huge branching cells which
run on into spheres, some of which may be from two to
four times the diameter of a yeast cell, and capable of
budding at several points, showing in fact, some of the
appearances of S. Cerevisiae ; only on a much larger scale
[Plate VIII., Fig. 4]. Its growth is accompanied by the
production of Alcohol and Carbonic Acid gas to a limited
degree, the maximum amount of Alcohol formed, being
according to Fitz, 3*5 to 4% by volume : (an experiment
of our own gave us 4% in a wort of Sp. Gr. 1063). A
fair supply of Oxygen facilitates its growth.
The mycelium of Mucor Racemosus, taken out of a
fermented liquid and exposed to the air on a nourishing
medium such as crushed germinating barley, reproduces
the aerial or mould form.
Mucor seldom appears in Beer, probably because the
fermentative activity of S. Cerevisiae, being so much
greater, a proportion of Alcohol is soon arrived at that
precludes its growth. We have heard of its being seen in
yeast, but only in connection with plant and process of the
most defective description.
MUCOR MUCEDO is also a commonly-occurring mould on
rotten fruits, mouldy bread, old yeast, damp barley, and
malt ; but it grows perhaps more readily on horse manure
than on anything else. It has a passing interest for us, in
that its mode of growth somewhat resembles that of Mucor
Racemosus, forming as it does, a definite sporangium,
at the extremity of hyphae proceeding from a white or
greyish mycelium, usually dark-coloured and visible to the
naked eye. Pasteur distinguished it from M. Racemosus
by the circumstance of its having on its sporangia-
The Moulds or Microscopic Fungi. 91
bearing hyphae, lateral branches which also terminate in
In Beer wort, instead of forming the well-defined ferment
forms that M. Racemosus does, it has a greater tendency
to form a branching mass of large and long cells, with here
and there huge swellings, filled generally with granulated
protoplasm and nuclei. It produces small quantities of
Any living portion of the original mycelium seems
capable of growing submerged in Beer-wort, which is
probably also the case with M. Racemosus.
Pasteur, on examining the adherent dust of grapes,
found, besides specific Alcoholic ferments, certain forms of
moulds, including Dematium Pullulans, which were capable
of producing in the grape-juice, cells closely resembling the
Saccharomycetes ; there is no evidence however, that he
obtained the phenomena of fermentation from the bodies
Brefeld has shown that many of the moulds, cultivated
in nutrient liquids, are transformable into torula forms
or cells resembling yeast, not usually classed as Saccha-
romycetes ; and he is strongly of opinion that the
Alcoholic ferments are the submerged sporular forms or
conidial fruit of moulds or fungi.
BLACK MOULD OF HOPS AND BARLEY.
In certain seasons, Hop and Barley samples are met
with that exhibit minute black spots or patches : if these
be scraped off with the point of a penknife, and placed
with a little moistening liquid preferably dilute alcohol
or dilute glycerine on a slide and examined with a com-
bination of about 300 diam rSti certain mould structures
may be observed, which from either source are generally
identical, and are characteristic of one of the varieties of
Ustilago, probably U. Carbo or U. Segetum, the "smut"
92 The Moulds or Microscopic Fungi.
of cereals. The chief peculiarity is the dark-coloured
(brownish black) hyphaeal growth, somewhat resembling
Oidium Lactis in form ; and the presence of simple and
compound spores. Barley and Hop washings are usually
found to contain fragments and spores of this mould (see
Chapter X.) The mere presence of the mould indicates
doubtless, a poor class of Barley or Hop, as the case may
be. In most Barleys these appearances are probably
emphasized during the sweating in stack. With hops,
the growth would be facilitated undoubtedly by imperfect
curing and damp storage, especially the latter. Mould of
any kind, in Barley, is generally more or less evident by
smell, excepting when the samples are kiln-dried. As in
the case of other moulds associated with Barley or Hops,
there is probably little to be feared from the actual growth
retaining any vitality throughout the Brewing process (for
Copper-boiling must mean practical sterilization) ; but what
is to be feared is the bad quality of materials showing
mould, and the deterioration that must ensue in the
structures of both barley and hops, from even a limited
growth of such organisms, apart from the unpleasant flavour
which they always impart to the material on which they
Mould spores of many kinds are so generally diffused
in the atmosphere, that they are often found attached to
the exterior of perfectly healthy vegetable products, and
given the necessary conditions such as damp, etc., it is not
long before growth renders their presence evident to the
Besides the Black mould mentioned, there is no doubt
that Hops are, in the "gardens," subjected to the destructive
influence of other varieties : the so-called Hop Mildew,
Sphaerotheca Castagnei, is probably the commonest. This
mould eventually forms black patches, and may be the
same as that we have already described as an Ustilago.
The Moulds or Microscopic Fungi. 93
We once had an inferior sample of hops in our hands
that, whilst in bale, had developed a yellow mould
curiously resembling the " condition" of the hop, the
spherical sporangia being about the same size as the resin
capsules. It is probable that this was the Eurotium form
of Aspergillus Glaucus before referred to.
Where moulds develop on the surface of bales kept in a
damp store, the infection is probably from the air, the
mould growing on the damp sacking and spreading inwards
to the hops. If the hops themselves are damp from
undercuring or exposure, the growth would be doubtless
FUSARIUM HORDEI, the red mould described by one of us
some years ago,* is, after Penicillium Glaucum, the most
frequently occurring mould in connection with growing
Barley. It is occasionally seen amongst inferior samples
of Barley, appearing as a crimson or pink tinted patch on
defective corns, usually at the germinal end ; fortunately,
it does not spread to healthy corns, but it may be
communicated to crushed ones. The most marked phase
of its development is the crescent-shaped compound spore
[Plate VIII., Fig. 5, a and d~\. During its growth it may
exhibit the following appearances : Mycelial and aerial
hyphae, sometimes forming internal spores which escape
from the end of the hyphae, and may be called pseudo-
spores [Fig. 5 b~\ ; Fasces, or bundles of crescent-shaped
spores on very short, thick hyphae [Fig. 5 a] ; Sporangia
on lateral and terminal or long hyphae [Fig. 5 c\.
The presence of F. Hordei usually indicates a poor
Barley. When submerged in beer-wort, the mould gives
an alcoholic ferment form somewhat resembling Mucor
MONILIA CANDIDA is the name under which Hansen has
described t a mould which, in certain phases of its develop-
* "Journal R. Micr. Soc.," Ser. II., Vol. III., p. 321.
f Carlsberg Report, Vol. II., part 4, 1886.
94 The Moulds or Microscopic Fungi.
ment, shows cells resembling Saccharomyces, remarkable
for the property they possess of causing, without previous
inversion, alcoholic fermentation in a solution of Cane
Sugar. The cells fall to the bottom of the liquid, multiply-
ing like yeast, and may come to the surface again, forming
The red growth of cells resembling Saccharomyces,
observed by Hansen and others in beer- wort, is caused
by organisms which probably bear a closer relation to
moulds than to Alcoholic ferments proper.
If it be desired to cultivate any particular mould, various
media offer themselves as favourable for the purpose :
Slices of boiled vegetables, e.g., potatoes, turnips, etc. ;
crushed germinating barley ; gelatine in small dishes : all
or any of these may be sown with detached portions of the
Spores may be grown experimentally in water alone, or
on wet sand. The vessel containing spores or the mould
growth, may be placed on a soup-plate containing a little
water, and should be covered with a bell-jar or some
suitable glass vessel, to exclude dust and secure a moist
atmosphere. Many of the precautions described under
Yeast and Bacteria may with advantage be adopted in
pure cultivations of moulds.
THE BACTERIA OR SCHIZOMYCETES.
IT is perhaps in connection with the Bacterial contami-
nation of fermentable liquids that Pasteur's researches
have their highest value. In his "Etudes sur le Vin" many
of the disease changes to which the French red and white
wines are at times prone, are traced by him to their sources
in certain specific forms of Bacteria, giving rise to acidity
and unpleasant flavours. As a sequel to this he made
Beer his study, and by a succession of beautiful and
original researches demonstrated the fact, amongst others :
that the changes involving perhaps the greatest loss to
which Brewers are subject, are those connected with the
growth of various kinds of Bacteria ; and that the exclusion
of these from the process by attention to various important
points, is one of the chief factors of success as regards the
It has become the custom for some scientists of a more
modern school, to underrate the successful efforts Pasteur
made to place the whole Brewing process on a more stable
foundation ; but the fact should not be lost sight of, that
had it not been for his brilliant work there would still be
much groping in the dark in connection with the science
of Brewing ; for after eliminating from the process the
96 The Bacteria or Schizomycetes,
disturbing conditions due to Bacteria, he paved the way for
a fresh departure as regards the study of the Alcoholic
We purpose in this chapter to give a general sketch
of the Identification, Classification, Life-history, and Cul-
tivation of Bacteria ; leading on to their connection with
Brewing, and the effects due to their growth and action in
fermented beverages, more especially in beer.
Some little confusion has arisen from the variety of
names that has been applied to the Schizomycetes or
fission-fungi, the words Germ, Microbe, Bacterium, Micro-
organism, all indicating the same class of organisms.
As in the case of the moulds there is no well-defined
distinction as to form, between Alcoholic ferments (Sac-
charomycetes) and Bacteria, nor between Bacteria and
Moulds ; the smaller size of the Bacteria in each case
constituting the principal difference. It is hardly necessary
to say that the microscope is the indispensable adjunct
to all kinds of work on Bacteria, and the lenses of the
instrument cannot be too good. For anything approaching
to a study of Bacteria, magnifications of from 400 to 1,000
diam rs - are necessary, but for ordinary Brewery observa-
tions 300 diam rs - will suffice.
Some of the earliest observations of Bacteria were made
about the year 1680 by Leuwenhoek, who in some letters
to the Royal Society speaks of minute organisms in the
lees of wine and beer, and also in putrid water, saliva, etc.
Dr. Hooke had three years previously to this brought
under the notice of the Royal Society, observations of
his on small moving organisms in infusions of pepper
and of other vegetable products. A certain Dr. King,
working contemporaneously with Hooke, also observed
and described minute organisms.
Seeing that 200 years have elapsed since these early
investigators recognised and described what were doubtless
The Bacteria or Schizomycetes. 97
Bacteria, it is rather strange that not till the last 15 or 20
years should any very rapid advance have been made in
this branch of scientific investigation. In recent times
progress has been indeed rapid, owing to the great talent
and skill brought to bear by men like Cohn, Koch,
De Bary, Zopf, and Pasteur. The name of Cohn
deserves more than casual mention, for he helped largely
in laying the foundations of a scientific study of Bacteria,
by very careful researches leading to an improved classi-
Before going into detail in connection with some of the
members of this " Kingdom of the infinitely little," as it has
been aptly termed, let us quote some every-day instances
of effects produced by the development of Bacteria. We
have the Souring of Wine, Beer, Milk, and other liquids ;
the ripening of cheese, especially in the case of such
powerfully-flavoured varieties as Limburg, Roquefort,
Camembert, etc. ; the putrefactive decomposition of meat
and fish ; and many other decompositions like those of
" Brewers' grains" and "spent hops," where a bad smell is
a noticeable feature. In all or any of the above-mentioned
cases, Bacteria may be easily detected by the Microscope,
and we recommend the student to obtain in the first place
a general idea of these organisms. Slime from a dropping
water-tap, or some steep-water from the makings, kept for
a day or two in a warm place, will usually furnish Bacteria
in some variety as regards shape and size. The Bacteria
appear in the form of round, or cylindrical rod-shaped
(rarely fusiform or spindle-shaped) cells of very minute size.
The diameter of round cells or transverse section of
cylindrical ones is generally about i ju ; the length of
cylindrical cells is not commonly more than 2 to 4 times
their transverse section, although some cells may attain
a diameter as great as 4/1, and occasionally grow to an
98 The Bacteria or Schizomycetes.
We will now enter into consideration of the structure
of Bacteria. The outer membrane is, as in the case of the
Saccharomycetes and Thallophytes, a fairly resisting and
elastic substance, probably of the nature of cellulose. It is
free from Chlorophyll, and in the majority of cases
colourless. The inner portion of the Bacterium cells
is a pasty mass rich in Nitrogen, called Protoplasm
or Mycoprotein, varying in density, transparency, and
refractive power. Many Bacteria enter into a motile or
actively-moving state at some period of their development ;
the organs by which this movement is effected being
hair-like protrusions, known by the names of Cilia or
Flagella, which having about the same refractive power
as water, are only seen with difficulty, even when the
movement ceases ; but they can be rendered more distinct
if the membrane of which they consist, be condensed by
treatment with Iodine solution or Osmic acid. It is
affirmed that some organisms have the power of retracting
the Cilium into the cell. A curious point is mentioned
by Zopf viz., that Micro-photography will sometimes
render visible the cilia that cannot be seen by the eye ;
the sensitized photographic plate being more susceptible
than the retina.
We may now deal with the plan of reproduction or
multiplication, of some typical Bacteria chosen from those
associated with the Brewing process, and for convenience
in grouping, take Cohn's classification of 1872.
Class I. Sphsero-bacteria = Dot or sphere.
,, II. Micro-bacteria = Short rods.
III. Desmo-bacteria = Threads.
,, IV. Spiro-bacteria = Spirals.
Class I., generally known as the Coccus or Micrococcus
form, propagates usually by simple division in two or more
directions ; the segments thus formed enlarge as the
The Bacteria or Schizomycetes. 99
fission progresses, and as they arrive at maturity are
liable to become disassociated from each other. This is
very well shown by an organism called Sarcina Litoralis,
found in putrefying sea water and spring waters. The
organism is shown on Plate IX., Fig. 3, in successive
stages of reproduction.
Another coccus form, but not a true micrococcus, is
brought about by the breaking up of longer or shorter
rod-lengths into ovals and spheres, by constriction of the
outer envelope at given points. Separated pairs of cocci
formed in this way are called Diplococci. Bacterium Aceti,
B. Pasteurianum, and B. Xylinum, afford at certain periods
of development, excellent examples of diplococci ; as shown
in Plate X., Fig. 4. Budding of one spherical cell out of
another has not, so far as we know, been observed in
connection with Bacteria.
The normal methods of reproduction of Classes II. and
III. are (a) By the continuous development of rod
lengths ; (b) By the formation of spores capable of germina-
tion, and consequent reproduction of the Bacterium form.
The organism Cladothrix dichotoma, affords a good illus-
tration of rod lengths, showing at the same time what is
called false-branching (see Plate IX., Figs, i and 2). As
an example of spore formation Bacillus Subtilis may be
referred to [Plate IX., Fig. 4].
The Spirillum forms of Class IV. are reproduced by
fission, sometimes in short lengths, sometimes in very long
pieces which afterwards break up into separate individuals.
According to Cohn, all Bacteria tend to reproduce a
constant and uniform type ; Micrococcus yielding Micro-
coccus, and Spirillum, Spirillum : but in the light of Zopf s
more recent researches this position is no longer tenable,
for he shows clearly that in the case of many kinds of
Bacteria, long rod lengths may produce short ones, and
even coccus forms. In fact almost every form assumed by
zoo The Bacteria or Schizomycetes.
Bacteria in general, may be furnished by one organism,
as for example, with Cladothrix dichotoma [Plate IX.,
Fig. 2], which shows coccus, rod, and spiral forms. It
was only to be expected that Zopf, after satisfying him-
self that distinct species of organisms could go through a
cycle of changes at some period in which they might
have departed from the typical form, and were not to be
morphologically identified should have devised a classifica-
tion to cover the differences of form he had encountered.
The following is his somewhat elaborate system :
Class I. COCCACE^E Micrococcus forms, and threads of
,, II. BACTERIACE^: Cocci, short rods (Bacteria), long
rods (Bacilli), long threads (Leptothrix) ; no
,, III. LEPTOTRICHEJI Cocci, Bacteria, Bacilli, Lepto-
thrix, and Spirals.
,, IV. CLADOTRICHE^: Cocci, Bacteria, Leptothrix,
Spirals, and false branching.
The first three classes include the forms mentioned by
Cohn ; class I. being the same as his. Criticising the
arrrangement, we feel inclined to remark that it was hardly
worth while establishing a new class for the organisms
A very elaborate classification of the Schizomycetes has
been devised by Flugge, but space will not allow us to
introduce it in detail. It contains two general groupings
into round and ovoid cells and cylindrical cells, with
about twelve different subdivisional groups. Very slight
morphological differences are made of much importance,
and generally speaking, the classification seems a cumbrous
one. Nageli includes the whole of the classes in the one
term Schizomycetes, and maintains that Bacteria are allied
to yeast. He classes all the microscopic fungi producing
decomposition as follows :
/' I /
\\ \ \i
\ \ ',
-ix Dichoiomcu $OQ Clcud. Dichotomy :
(after ZopfJ (aft". z opf)
:. J. F/c.4. FIG. 5.
Bacterium Termo 6 -^
J E WRIGHT DEL.
The Bacteria or Schizomycetes. 101
Mucorini or Moulds. -
Saccharomycetes or Alcoholic ferments.
Schizomycetes or Bacteria.
It then appears that in the majority of cases it is
almost impossible to identify a Bacterium from its mere
appearance at any given time. Zopfs statements to this
effect are supported by Klebs and other workers who
have seen rod and spirillum forms produced by the same
There seems to be a very general tendency for Bacteria
in the form of rods and threads, to become curved or
crooked, especially with alterations of nourishment. Be-
sides the normal forms exhibited by Bacteria, very
curious deformities are occasionally met with, showing
dark coloured protoplasm and marked peculiarity of form,
including great enlargement of certain cells ; insomuch that
were the portions viewed alone, one would not associate
them with the original Bacteria. Such deformities are
called Retrograde or Involution forms, and are probably
brought into existence by deficient nourishment.
Let us return to a closer consideration of the reproduction
by fission, or division of rod lengths. Zopf says that the
membrane by which the Bacteria are enveloped is in many
cases capable of thickening, and then dividing into layers,
one of which (the inner) is capable of differentiating itself,
whilst the other (the outer layer) grows for a longer or
shorter time, till finally it may yield to the pressure of
enclosed cells and some of these last be pushed out,
as for example with Crenothrix Kuhniana shown in
Plate IX., Fig. 6 an organism which is somewhat closely
allied to the Mucorini, but classed by many authorities
amongst Bacteria : it also affords a striking example of cell
formation, by differentiation of the protoplasm in the
We can now proceed to consider in some detail the
IO2 The Bacteria or Schizomycetes.
reproduction of Bacteria by spore-formation, a process
first observed by Cohn in Hay Bacillus (Bacillus Subtilis)
[Plate IX., Fig. 4]. Spores are formed by a condensation of
cell protoplasm into small spherical masses with a new and
independent membrane. A disintegration of the old cell
envelope often takes place about the same time, thus
freeing the spores. The process of sporulation is plainly
seen in two kinds of Bacteria, the Bacillus Subtilis already
referred to, and the Butyric ferment (Bacterium Butyricum)
[Plate X., Fig. 7]. Sporulating Bacteria may usually be
found in decomposing Brewer's grains, or in hay-infusions
or steep- water kept at 80 to 90 F., in the latter cases
the sporulation usually takes place after an active growth
of the Bacillus ; they are seldom met with in Beers, but
we have once or twice seen what was apparently Bacterium
lactis in the sporulating state. In Plate IX., Fig. 5, we
give examples of germinating Bacterium-spores, very highly
Bacteria under certain circumstances, generally those of
restricted growth, develop a very curious condition known
as the Zooglcea or resting state, caused probably by the
gradual reproduction of Bacteria in close proximity, and
the tendency the organisms then have to largely increase
the enveloping material, which at the same time passes
into a gelatinous condition. This may proceed until the
contour of the separate cells is nearly lost, and an almost
indistinguishable mass may remain, where formerly well-
defined Bacteria were seen. Sporulation may go on at
the same time. Plate IX., Fig. 7, shows Bacterium Termo
in the zooglcea form.
To proceed with some of the more general phenomena
associated with the growth of Bacteria. The production
of a definite pigment is a property belonging to a fairly
large class called Colour-bacteria. Amongst the colours
produced (which are usually diffused in the cultivating
The Bacteria or Schizomycetes. 103
medium) are Crimson, Blue, Scarlet, and Yellow. The
Bacterium form is in most cases a small sphere. Boiled
white of egg is an excellent nourishing material for these
growths. A great variety of products is obtained from
Bacterial decomposition ; amongst the commonest are free
acids such as Formic, Acetic, Lactic, Butyric, and other
organic acids, formed from a variety of substances, viz.,
alcohols, glycerine, vegetable gums, starchy bodies and the
Carbohydrates generally; or Ammonia may be produced
from certain nitrogenous bodies, especially amides and
albuminoids ; or an oxidation of the Ammonia to Nitric and
Nitrous acids may ensue a highly important action that
is always going on in porous soils charged with sewage and
decomposing animal and vegetable matters, thus bringing
them into a form in which they can be assimilated
by plants, and so enter again into the round of life.
Hydrogen, Nitrogen, Sulphuretted Hydrogen, Marsh gas,
Phosphoretted Hydrogen, and Carbonic acid gas are also
products of decomposition by the intervention of Bacteria.
Nageli has advanced the same theory in connection
with Bacteria that he holds respecting Yeast, viz., that the
decompositions are set up by molecular vibrations of the
protoplasm, which are communicated to substances within
a certain radius of the organism.
In the case of all Bacterial decompositions, a point is
reached when the action of the organisms is arrested or
checked by the nature of the products, which act towards
them as poisons, whether they be acids, alcohols, or other of
the substances mentioned. Doubtless a sudden immersion
of Bacteria in solutions containing even less of those sub-
stances than is normally produced, would arrest the activity
of the Bacteria or kill them. The same thing holds to a
certain extent in the case of the Moulds (more especially
in a submerged state) and the Saccharomycetes.
Bacteria thrive best in weakly alkaline solutions, con-
IO4 The Bacteria or Schizomycetes.
taining Carbon and Nitrogen, etc., in the form of Carbo-
hydrates and Albuminoids. After the Bacteria have ceased
growing, Saccharomyces forms and moulds may appear.
In acid solutions, such as Wine-must and Beer- wort (which
last has a slight normal acidity), the sequence is different,
the Saccharomycetes developing preferably, followed by
Bacteria, Aerobic ferments, and lastly moulds.
Bacteria have a considerable affinity for Oxygen gas,
especially when they are in the motile state. This is
shown in an interesting way when a cover glass is
placed over a drop of liquid containing Bacteria, on a
microscope slide, air bubbles being also enclosed : the
moving Bacteria flock to the edges of the bubbles, and also
to the edge of the cover-glass.
With regard to the action of electricity on Bacteria : a
weak current affects them but little, but a stronger one
can sterilize a solution in a time proportionate to the
strength of the current ; sterilization being more complete
at the positive pole of the Battery. The killing of the
organisms present, does not however, prevent newly
sown Bacteria subsequently developing. It is probable
that Spores would not be killed by even a powerful
current of electricity.
Very little exact work is extant in connection with the
effect of chemical substances on Bacteria. It appears that
mineral and fruit acids, and some other organic acids, have
a marked deterrent effect ; this is notably the case with
Bacillus Subtilis, which is hindered in its growth by even
a weakly acid solution. Sulphurous acid and Salicylic acid
have a well-marked antiseptic effect on bacteria, and we
shall have occasion to make some further remarks on their
Many substances having a markedly destructive action
on developed Bacteria affect the spores of the same
but little, for they have been dipped in concentrated
The Bacteria or Schizomycetes. 105
solutions of Sulphate of Copper and Mercuric Chloride
without losing their capacity for germination. It is also
well known that the spores of some bacteria, e.g., Bacillus
Subtilis, can withstand exposure to a boiling temperature
for a limited time without sacrificing their vitality.
Gradual and nearly complete loss of water may be
sustained by bacteria without loss of vitality ; desiccated
spores of some bacteria retaining their power of germina-
tion for several years. Forms other than Micrococci or
Spores do not however, live long in a dry state.
Temperatures below 60 F. are unfavourable to the
development of bacteria, but between this temperature and
130 F. each kind of bacterium finds some very favourable
It will be desirable to consider in some detail the chief
methods of research adopted for Bacteria. In connection
with the growth and culture of these organisms, the
following important questions present themselves :
i. In what plasma or food stuff does the Bacterium
thrive best ?
2. Through what stages of development does it go ?
3. As to the products of decomposition by specific
4. The behaviour of the organism in relation to
5. The influence of temperature.
6. The action of antiseptics.
We shall in some way or another touch on nearly all
these points. At present we purpose dealing with modes
of cultivation :
Having obtained a fair example of the particular kind
of bacterium one is desirous of cultivating, the next thing is
to provide a suitable plasma and keep out air-borne germs.
Amongst the various cultivating media there is nothing
io6 The Bacteria or Schizomycetes.
much better for bacteria than gelatine, which can be
adapted for use in a variety of ways ; the addition of
meat-peptone or meat extracts, such as Liebig's, Brandt's,
etc., undoubtedly increase the nutrient power. (See
Appendix C i.)
Space will not permit us to enter into the minutiae
of the sterilization of vessels, infusions, etc. In all cases it
is a matter of employing heat in such a manner as to kill
germs that are not wanted.
For bacterial research, a room that is as far as possible
free from dust is desirable. Glycerine when smeared on
plates, and on the inside of Bell-jars used in connection
with cultivations, will arrest floating dust in an effective
manner. A supply of wide-mouthed bottles, test-tubes,
and flasks for a stock of gelatine, with a few other small
pieces of apparatus, will enable one to grow ordinary
bacteria. Such things as sand-baths, water-baths, drying-
ovens, incubators, etc., can with a little ingenuity, easily be
contrived out of every-day appliances, if one does not care
to incur the expense attending their purchase.
There are several methods of obtaining a pure cultivation
of one particular organism. Speaking generally, they
commence with the excessive dilution (described in
Chap. V., page 63), of a liquid containing a preponderating
quantity of the organism sought. The Ranvier or Bottcher
moist chamber may be used with gelatine ; or " plate
cultivation " (which has of late years been developed in
connection with water analysis) may be carried out with
the same medium, as follows :
A portion of the liquid containing the organisms it is
desired to cultivate, is withdrawn by a sterilized pipette
and run into sterilized gelatine-peptone (Appendix C i),
which has been melted in the test-tube containing it, by
immersing in a water bath at 86 F. Complete mixture is
effected by shaking, and the fluid is run on to a clean,
The Bacteria or Schizomycetes. 107
sterilized, uncoated photographic plate, resting in a perfectly
horizontal position (secured previously by use of a spirit
level) on a glass tripod standing on a soup plate. The
arrangement is immediately covered by a glass shade. A
2 / solution of mercuric chloride, standing to a slight depth
in the soup-plate, acts as an antiseptic seal. The glass
plates are preferably sterilized by heating in a shallow metal
box ; the rest of the apparatus by rinsing with mercuric
The whole arrangement is next placed in a chamber
maintained at 58 77 F. for incubation, which extends
over three to five days. The plates are daily inspected,
without removing the glass cover, and the appearance and
growth of any colonies watched ; before these last coalesce,
the plates are withdrawn for microscopical examination.
The points to be noted are
(1) The number of colonies conveniently ascertained
with a hand-lens and a superimposed glass plate ruled in
(2) The effect of the growth on the gelatine itself.
(3) The nature of the organisms forming the colony, as
ascertained by the microscope.
Marked peculiarities are at times, met with in gelatine
cultivations ; for instance, the formation of gas bubbles,
usually of lenticular shape, but varying according to the
density of the gelatine ; and the appearance of spherical or
pear-shaped liquid cavities, whose contents are usually acid.
A greatly improved definition under the microscope of
the membranes, and of the internal parts of Bacteria, is
obtained by staining with various dyes, a process very
elaborately described in some of the works on Bacteriology.
Staining in a simple form may be carried out as follows :
Two or three drops of the liquid on a slide (free, if possible,
from matters other than bacteria) are dried off gradually on
a metal plate, at a temperature of about 90 100 F. A
io8 The Bacteria or Schizomycetes.
drop of very weak Rosaniline or Methyl-violet solution is
put on to each of the dried spots, and evaporated to
dryness as before. The surplus dye can be removed with
weak alcohol or dilute nitric acid, which are in turn washed
away with a little water, and some clove oil can be put on
the spots, followed by Canada Balsam (Appendix B).
If the slide be wanted for immediate examination, it is
unnecessary to remove the surplus dye ; in such a case a
little turpentine, followed by clove oil, will give very good
specimens. Eosine is a good dye for immediate examina-
tion, but fades on keeping. We have already alluded to
the use of Iodine and Osmic acid for rendering bacterial
structures more plainly visible : they are both more suitable
as mere reagents than for permanent specimens. The
so-called pathogenic organisms, or bacteria associated with
diseases of men and animals, interesting though they may
be, are of course outside our province.
It is a matter of certainty that Bacteria have existed on
this earth from some very distant period of its history :
Van Tieghem found them in the fossil roots of Coniferae
and other fossilized vegetable remains from the coal-
The relationship of Bacteria to the Moulds would seem
to be much stronger than to the Alcoholic ferments, turning
on this point more especially, that the Saccharomycetes do
not exhibit any motile forms provided with Cilia ; whereas
in certain stages of their growth the moulds do. All three
classes of organisms may form spores, but the Saccha-
romycetes do so under somewhat exceptional conditions.
Bacteria, as a rule, require more complex forms of
nourishment than Moulds or Saccharomycetes ; for the two
last-mentioned will thrive fairly well in a mineral solution
in which the carbon and nitrogen are represented by
ammonic tartrate, whilst Bacteria grow but feebly in the
same. Bacteria then may be ranked higher than moulds or
The Bacteria or Schizomycetes. 109
alcoholic ferments, for although they show characteristics
which at each end of the scale join them to separate
kingdoms, making it a question between animal and
vegetable life, the weight of evidence seems to us to point
out a much closer alliance to the former than the latter
condition of existence. Before proceeding to discuss the
various forms of Bacteria that are associated with fermented
liquids, a few words as regards the immediate source of
these organisms will not be out of place. It is to the air we
have to look, and it is not difficult to account for their
presence in it, as Bacteria are constantly being produced in
myriads by all kinds of decomposition of animal and vege-
table substances in free contact with air. The products of
decomposition or putrefaction becoming dried up are, with
the myriad organisms and spores that they include, spread
broadcast, the infinitesimal weight and size of the bacteria
and their spores causing them to be carried to great
distances, and easily kept in suspension by currents of air.
In all populous districts Bacteria are everywhere, and on
pretty well everything, and as a consequence we swallow
them probably by thousands daily. Where the air is per-
fectly calm, as in small enclosed spaces, bacteria settle
down completely. Some interesting results relative to
organisms in the air were obtained by Miquel from observa-
tions made at Montsouris. In a cubic metre of air he found
In the Autumn ... ... 142 organisms.
,, Summer 105
In a cubic metre of air in the Rue de Rivoli, Paris,
he found at one time 5,500 organisms. The experiments
of Tyndall, Miquel, and others, have shown that the air at
high elevations for instance in the Alps is free from
Bacteria. We may then consider that the air is the
1 10 The Bacteria or Schizomycetes.
reservoir from which the foreign organisms appearing in
beer and other fermented liquids, are derived ; though
naturally we have to reckon on their possible and probable
multiplication in the afore-mentioned media. Hansen, in
the course of experiments that we have already alluded to,
found that the air of Carlsberg contained a large number of
organisms capable of growing in Beer-wort, and included
forms of Bacteria that will be spoken of later.
We purpose dealing categorically with the Bacteria that
may be associated with the process of brewing, and will
group them thus:
Coccus OR MICROCOCCUS (including chains of Micrococci).
The Viscous ferments.
MICRO- BACTERIA (short rods).
Pasteur's lactic ferment.
Bacterium Butyricum (also called Clostridium
Butyricum and B. Amylobacter).
DESMO- BACTERIA (including long and sliort threads).
THE SARCINA GROUP.
Some very interesting and suggestive work has lately been
published by Paul Lindner,* on this group of organisms,
* Nachrichten iiber den Verein Versuchs = und Lehranstalt fiir Brauerei in Berlin.
Die Sarcina-organismen, etc.
The Bacteria or Schizomycetes. 1 1 1
which systematizes the information that was extant
before the experiments commenced, and adds thereto much
fresh matter. We will make some brief extracts : An
organism of the Sarcina type but not a true Sarcina, seems
to have been alluded to by Pasteur,* as causing when
present in beer, a peculiar rough acidity and characteristic
odour. Berscht mentions a definite Sarcina disease of
beers, causing a cloudiness which passed off in a few days
leaving the beer clear but with a disagreeable smell.
Hansen found Sarcina in yeast water : P. Lindner has
seen it in pitching yeast itself: and several observers,
amongst them Brown and Heron, have found it in malt
extracts. S. Von Huth has sought to establish a connection
between the fact of Sarcina growing readily in horse-urine
and stable-manure, and its appearance in beers : tracing
the contamination through air, water, ice, vessels, etc. He
maintains that Sarcina does not grow in liquids that readily
acidify, and notices that Sarcina-beers after a time lose their
characteristic taste and smell, but become vinous ; and
infers that when the development of acid reaches a certain
point the growth is arrested. P. Lindner, using Hansen's
moist chamber and gelatine mode of cultivation, with
decoctions of chopped hay (which favour the growth of
Sarcina), or malt extract solutions, and infecting these with
material from various sources, managed to separate and
identify several kinds of Sarcina, viz. :
Pediococcus acidi lactici.
* " Studies on Fermentation," trans. Faulkner and Robb. p. 6. Plate I., Fig. 7.
f "Die Bierbrauerei," 1881, p. 214.
1 1 2 The Bacteria or Schizomycetes.
Pediococcus cerevisiae seems to be the one investigated
by S. Von Huth, whose observations as to its presence in
stable-manure are corroborated by P. Lindner : the latter
has also seen it in well water used for cleansing purposes in
a Brewery. It occurs in German beers, notably in Berlin
Weissbier in the viscous condition, when it is probably the
cause of the viscosity.
Pediococcus acidi lactici probably the same as an
organism seen by Hansen in the form of many-celled
cubical packets or groups gives rise to a considerable
quantity of lactic acid. The diameter of the single coccus
= 0*6 to i M. Both this organism and Ped. cerevisiae are
by no means uncommon in German beer, and Lindner says
that the intentional souring of worts in German distilleries
is often carried out by Pediococcus acidi lactici.
Pediococcus albus was found in two spring waters ;
resembles the foregoing forms ; it can give rise to a white
Sarcina Candida ; a form observed by Reinke in a
Brewery water-tank ; gives brilliant white growths. Dia-
meter of coccus 1*5 17 ju-
Sarcina aurantiaca ; produces an orange coloured growth
on gelatine ; found in Berlin Weissbier. Mentioned by
Sarcina flava (de Bary) ; a Sarcina producing a yellow
pigment, found during some of the experiments on Ped.
cerevisiae, previously described by De Bary, and probably
the same as Schrceter's Sarcina lutea. Diameter of coccus,
8 fi tO 2 2'5 j".
Sarcina maxima [Plate X., Fig. i] ; packet-forms met
with in malt mashes. Diameter 3 4 /u.
P. Lindner summarizes his observations thus :
i. The Sarcina group is represented by numerous kinds
associated with fermentation. It is almost impossible to
* Grundriss der Bacterienkunde. 1887, p. 166.
Sarcina Maxima '
Fed. Acidi. Lactici (?
Viscous Ferment- *-*- a
Lactic Ferment T*
Bacterium Bufyricum 3f.
Bac. Subtil is
BEMROSE & SONS. LIT
The Bacteria or Schizomycetes. 113
identify them by mere microscopical examination. Culti-
vation in different media is necessary.
2. Some of the organisms show a two-dimensional
growth, viz., Fed. cerevisiae, Fed. albus, and Fed. acidi
3. Others show a three-dimensional growth, but only
in hay-decoction, they are Sarcina Candida, S. aurantiaca,
and a kind identified by Schrceter, S. rosea.
4. Others grow almost exclusively in the typical Sarcina
form Sarcina flava and S. maxima.
5. None of the varieties forms spores. P. cerevisise
gives abnormal or involution forms. P. albus, P. cerevisiae,
and S. aurantiaca can form films.
6. With the exception of S. maxima, which was not
investigated in this respect, the different kinds produce
varying quantities of lactic acid, with traces of formic acid.
7. Nearly all kinds liquefy gelatine sooner or later.
8. A temperature of 60 C. (140 F.) kills any of them
in a short time.
In addition to the kinds mentioned by Lindner, as
investigated by himself and other workers, there remain
some few forms of Sarcina which we will merely mention,
as they have not, as far as we know, any traceable
connection with the Brewing process. They are
S. Reitenbachii (Caspary), found on water plants.
S. Hyalina (Kutzing), in marshes.
S. Litoralis (already mentioned in connection with the
mode of growth of Bacteria), found in spring water
and putrefying sea-water.
Sarcina, as observed in English beers, is found in groups
of four or tetracocci ; also as diplococci ; and may be
disassociated into separate coccus forms. Sometimes the
cocci are grouped symmetrically, at other times irregularly
[Plate X., Fig. 2]. We have seen Sarcina not unfrequently
in " forced " ales ; also in ales returned to the Brewer ; and
ii4 The Bacteria or Schizomycetes.
lately we have seen some good examples of it in cask ales,
some of which had become acid and vinous in store. The
chief results of a free growth seem to be a high acidity
probably from lactic acid sometimes preceded and accom-
panied by a vinous flavour, a harsh bitter, or else a
peculiar woody taste. The Sarcina growth is generally
accompanied by other bacteria. We are inclined to believe
that two forms of Sarcina are met with in English beers :
One, a more symmetrical and less easily growing organism,
probably Lindner's Pediococcus cerevisiae ; the other, in
less symmetrical forms, appearing in greater quantity, and
accompanied by acid production is, we think, Lindner's
Pediococcus acidi lactici. Plate X., Fig. 2, furnishes, in
our opinion, an example of the latter. We have made
experiments to determine whence infection from Sarcina
may proceed, and have convinced ourselves that very old
wooden vessels constitute one source ; the organisms being
not unfrequently discoverable in the spongy deteriorated
wood. How they effected a lodgment there, and whence
derived, are questions not so easily answered ; impure air
or cleansing water, may in some cases furnish a solution.
Apart from direct infection of beers which show Sarcina,
there must be a predisposition to nourish the particular
organism ; and as regards this point, the following remarks
We have encountered Sarcina in ales which were brewed
with a large percentage of inferior moist sugar containing
nitrogenous organic matter and phosphates. Various
experimenters have shown that neutrality or alkalinity of
nutrient solutions favours the growth of Sarcina ; a deduc-
tion from this being that reduction of the normal acidity of
beer might be a predisposing condition. Amongst possible
causes are included under-cured malt, especially if slack and
otherwise of inferior quality. It is rarely the case that
Sarcina gains any headway in English beers, though we
The Bacteria or Schizomycetes. 115
have encountered it more frequently this year (1889) than
at any previous time in the last twelve years ; and it would
appear to have some direct connection with the character
of the season's malt. Lager beers seem much more liable
to Sarcina, owing very possibly, to the low temperature of
malt-curing and the light hopping.
Or the passing of fermented liquids into a viscous or
"ropy" condition, is by no means an uncommon phenomenon.
Peligot^ seems to have been the first to notice a special
ferment capable of producing it.
Pasteur t subsequently speaks of the viscous state in
connection with wort and beer, and describes a special
ferment [Plate X., Fig. 3], which is capable of transforming
certain sugars into a kind of gum, together with Mannite
and carbonic acid gas. Any acid formed such as Lactic
and Butyric, resulting probably from other organisms
present at the same time.
Viscous Beers are fortunately, comparatively rare. In
most of the cases we have encountered, the quantity of the
organism present seemed to bear a very slight relation to
the effect produced. In one or two cases we have seen
the organism in the chain form, but more generally in the
coccus condition or with a tendency to form tetracocci, the
latter fact rendering it probable that there is a relationship
to one of the Sarcina forms described by Lindner, possibly
Pediococcus cerevisiae. The diameter of the cocci is 1.2 to
1.4 n- By infection we have frequently excited marked
viscosity in cane sugar solutions with very little clouding
and with the production of an exceedingly small quantity
of the organism, which strengthens our view that the
* Traite de Chimie de Dumas, vol. vi., p. 335, 1843.
f "Studies on Fermentation," trans. Faulkner and Robb, p. 5.
1 1 6 The Bacteria or Schizomycetes.
viscosity is more especially the result of some unorganized
ferment eliminated by the Bacterium.
Very little of a definite character can be advanced as to
the causes which favour viscous fermentation in Beer ; it
is probable that inferior and very slack malt, light hopping,
and imperfect cleansing owing to the nature of the worts
and the weakness of the yeast all tend to do so. Direct
infection from cask seems to us quite a possibility, where
ropiness only declares itself occasionally and not in con-
nection with a whole brewing.
Various artificial solutions can be made, which favour the
growth of Sarcina, for instance : Yeast-water, made by boil-
ing up yeast with water and filtering ; aqueous extracts of
wheat flour, barley and rice, with some added sugar ; and the
liquids mentioned by Lindner, viz. : sweet wort, and a
decoction made by treating chopped hay with boiling water.
Neutralisation of any free acid in the solutions seems to
materially aid the growth, especially if any acid subse-
quently produced be neutralized as it is formed, by introducing
powdered chalk, marble, etc. According to Pasteur the
amount of gum produced does not stand in constant
relation to the sugar decomposed, and he therefore thinks
that there are different viscous ferments, one of which forms
only gum. At the present time there is considerable scope
for investigation of viscous fermentation as there is com-
paratively little known about it. Before leaving this subject
an interesting fact may be mentioned, viz. : that the
phenomena of viscous fermentation are exhibited by an
organism called Leuconostoc mesenteriodes, which has the
power of converting large quantities of the juice of the
sugar-beet into a mucilaginous mass, in a comparatively
short space of time ; causing complete loss of the material.
We merely mention this without wishing it to be inferred
that there is any connection proper between Leuconostoc
and the process of Brewing,
Tlie Bacteria or Schizomycetes. 1 1 7
Or Bacterium Aceti, as it is perhaps preferably termed,
also popularly known as " Mother" of Vinegar, is the
organism commonly associated with a change that alco-
holic liquids are liable to undergo, during which the
alcohol is converted into acetic acid, and this last subse-
quently into water and carbonic acid gas. The appearance
of a film or pellicle on the surface of the liquid is a very
ordinary accompaniment of its growth. Pasteur was the
first to establish the known relation of the organism to its
products : he showed, moreover, that if the action of the
ferment was weakened, Aldehyde may be first produced
from the alcohol ; the consequence of which would, as
regards beer, be a vinous flavour. Acetic ether may also be
produced at the same time and considerably enhance this
On referring to Plate X., Fig. 4, the organism is seen in
the characteristic chain and diplococcus form, the smaller
dimension of the latter being about i p. Bact. Aceti is
coloured yellow by Iodine.
Bact. Aceti has been made the subject of a very careful
investigation by Adrian Brown * who took all precautions
to secure pure cultivations. He describes it as forming a
greasy pellicle, inclined in the early stages of its growth to
climb up the moist surface of the containing vessel. The
liquid below the pellicle is usually turbid from suspended
cells. In liquids free from oxygen it does not increase but
keeps alive for a long time. It forms figure-of-8 cells 2 /*
long, united into chains of varying length and sometimes
the chains are composed of distinct cocci. Adrian Brown
also observed abnormal or involution forms 10 15 n long,
and of a dark grey colour. The shorter rods and cells
of B. aceti, when floating freely in the liquid, are motile.
* J. Chem. Soc. Transactions, 1886, p. 172, and 1887, p. 638.
1 1 8 . The Bacteria or Schizomycetes.
Acetic acid is the one and only acid formed by a pure
growth of B. aceti, and it may be further decomposed
into Carbonic anhydride and water, thus substantiating
Pasteur's statements. Where alcohols other than ordinary
or Ethylic alcohol, are present, B. aceti produces acids
corresponding to them, and it seems to us that this fact
is calculated to throw some light on the variety of flavours
produced by the ageing and incipient decomposition of
alcoholic liquids, which last may be considered as being
more or less prone to the incursion of Bact. Aceti on
exposure to the air, and especially so where the liquids
are directly infected, as for instance, by an acid cask. The
organism is made use of in vinegar factories ; the liquids
to be acetified being passed through vessels containing
porous material, such as shavings, etc., strongly infected
with the Bacterium. Liquids that contain over 10 /o f
alcohol do not allow this organism to thrive. Tem-
peratures approaching 80 90 F. are very favourable to
Bact. Aceti figures very often in ales returned in partially
filled casks, the free exposure to air being the determining
factor of its growth. In imperfectly-corked bottled ales
it sometimes appears as a film, as also in defectively
stoppered forcing flasks. A very moderate infection of
B. Aceti will cause marked acidity and deterioration of ale;
and there is no mistaking the presence of its product,
acetic acid, with its highly characteristic flavour. With a
normal process, and due attention to cleanliness of vessels
especially cask plant there is comparatively little risk
from B. Aceti.
Hansen^ has given the above name to a form of Micro-
coccus which has the same appearance as B. Aceti, and
* Meddelels.-r fra Carlslx-rg Laboratoriet, Andet Hefte, 1879, pp. 73 and 96.
T/ie Bacteria or Schizomycetes. 119
like it, produces acetic acid: it is in fact, only distin-
guishable by its giving a blue, colouration with Iodine, this
characteristic displaying itself however, through successive
Is an acetic ferment which forms cellulose. It was
discovered by Adrian Brown, and described by him* as
being identical with the so-called vinegar plant. It was
grown in red wine diluted with half its bulk of water, and
rendered acid with i / of acetic acid in the form of
vinegar. Beyond the production of acetic acid, the main
peculiarity in connection with the growth of the organism
is the formation of a surface membrane of cellulose, which
if shaken down, is renewed time after time, and appears
to be the only form in which the ferment develops,
though the membrane may in some cases be dispersed
through the liquid, giving a jelly-like appearance.
Microscopically, the organism exhibits itself in lines,
embedded in a transparent, structureless film. The bacteria
are most commonly rods about 2 ju in length, several often
being united together. It is sometimes seen in a micro-
coccus form, which Adrian Brown suggests may be spores ;
also in long twisted threads, 10 30 n in length, of a
Leptothrix nature. It does not exhibit the large swollen
involution forms of B. aceti. A temperature of 28 C.
(82*4 F.) is most favourable for its growth. Gives rise to
the same chemical changes as B. aceti. The formation of
the membrane constitutes the chief difference between the
PASTEUR'S LACTIC FERMENT,
Shown in Plate X., Fig. 5 ; occurs as a small rod
bacterium generally contracted in the middle, giving some-
what of a figure-of-8 shape. It often occurs in short
* J. Chem. Soc., 1886, Trans., p. 432.
I2O The Bacteria or Schizomycetes.
chains of 2 or 3 individuals. It is a question whether
this bacterium is the same as the short rod form seen in
beers, which we are accustomed to regard as B. lactis, but
for our present purposes it will be convenient to consider
them under the same title.
By lactic fermentation is understood the transformation
of certain substances into lactic acid, the presence of which
in liquids becomes evident by a sharp acidity not necessarily
accompanied by any distinct flavour, as in the case of acetic
acid. When milk turns sour spontaneously, the sugar it
contains is converted into lactic acid, and it was from this
source that the acid was first extracted. It would appear
that the presence of nitrogenous albuminoid matter is, in
addition to sugar, required for lactic acid fermentation. The
temperature most favourable to action is 120 F., and the
souring of a liquid such as wheaten flour and water, goes
on with extraordinary rapidity at this temperature, a large
amount of acid being formed before the action is arrested.
By neutralisation of the liquid with chalk, etc., a much larger
quantity of the acid is produced. B. lactis is said to be
able to grow without free oxygen : if it does so, it is
probably only to a limited extent in comparison to its
growth with free access of oxygen.
The German distillers believe that a small percentage
of lactic acid in the worts secures a more vigorous fer-
mentation, and one less likely to develop bacteria. The
presence of lactic acid is secured by exposing a small
green-malt or other mash, infected with lactic ferment, to
a process of souring for many hours at the favourable
temperature 120 F. ; it is then mixed with the mash proper.
It is more than probable that a considerable variety of
organisms produce lactic acid ; thus it will be remembered
that Lindner has observed lactic acid production with
organisms of the Sarcina group, especially with Fed. acidi
TJie Bacteria or Sckizoniycetes. 121
It is generally assumed that a small quantity of lactic
and acetic acids is always present in beer ; we do not
think, however, that the free acid of beer necessarily
consists of these. Bact. lactis as seen in beers is generally
in the form of small rods, 2 to 3 M in length (see Plate X.,
Fig. 6), and sometimes in threads containing from 2 to 5
individuals ; it is not certain, however, that this form is
B. lactis. The single rods are often motile.
Bacterium lactis is the most commonly occurring disease-
organism encountered in the brewing process, for it is
exceptional to meet with beers and yeasts that do not
show an individual here and there when submitted
to microscopical investigation ; and in most breweries it is
discernible at all times in varying quantity. The degree
of risk attending its presence depends mainly on the
destination of the ales ; that is to say, whether they are
for "stock" or for a " quick " trade; for objectionable as
bacterial contamination in a brewery is, there is a much
greater margin for it in the latter case than in the
former, the beers not having time to turn sour unless the
contamination and yeast deterioration are so marked as to
place the source of the existing trouble beyond a doubt.
In the case of stock ales it goes without saying that too
much care cannot be taken to ensure freedom of yeast and
beer from B. lactis or other disease organisms. With the
present method of brewing there must be contamination in
various ways, but it may be reduced to a minimum by
careful selection of yeast, and by due attention to the
process ; and with proper precautions, beers of such
character can be brewed, that the few Bacteria remaining
in them are almost inert, normal secondary fermentation
being the only change,
A small cylindrical bacterium about i "5 to 2 n long,
122 The Bacteria or Schizoinycetes.
having a central constriction, giving it somewhat of the
diplococcus or .figure-of-8 appearance. It is about the
commonest accompaniment of rapid putrefaction and
decomposition, especially in meat infusions. It is actively
motile, having a cilium or flagellum at each end. This
organism was investigated by Cohn, who describes amongst
other things the well-marked Zooglcea state, which it
enters into [Plate IX., Fig. 7], alluded to earlier in this
chapter. Bact. termo can multiply with enormous rapidity.
In its ordinary state it is seldom noted in Beer and yeast,
but may be found in the slime of pipes, accumulations in
the corners of fermenting and cleansing vessels, etc., etc.
It is possible that when present in worts its habit and form
become somewhat modified, rendering it perhaps similar in
appearance to B. lactis.
Known also as Bacillus amylobacter and Clostridium
butyricum, is an organism consisting of short cylindrical
or slightly ovalled rods of somewhat varying length, their
smaller dimension being about i ^. [Plate X., Fig. 7.]
Motile forms have been observed by Pasteur, who observed
also that the organism sometimes formed chains com-
posed of the smaller individuals : he also investigated
the. chemical functions of the organism. B. butyricum
very readily enters into the sporulating state, forming
well-defined highly refractive spores, which as the original
cell wall of the bacterium shrinks in and disappears, show up
very plainly. At certain stages of its growth the organism
may give a blue colouration with Iodine.
As its name implies, this bacterium is commonly asso-
ciated with fermentations in which the production of butyric
acid is the main feature ; the presence of the acid being
declared by the peculiarly disgusting odour which is one
of its attributes,: Butyric acid is produced from substances
The Bacteria or Schizomycetes. 123
capable of undergoing lactic fermentation, e.g., Sugars,
Carbohydrates, Fruit-acids, and Albuminoid substances.
The temperature favouring its action most, is about 100 F.,
but like other organisms, it will grow at temperatures
somewhat above, and considerably below this point. The
organism must be pretty liberally dispersed in the air, as
solutions of Cane Sugar, with the addition of a little
phosphate of soda or potash, usually develop Butyric acid
when placed on the forcing tray (see Heisch's test,
As regards the connection between Bacterium butyricum
and the process of Brewing : The organism is not
discoverable in the yeast and beer associated with a
normal process. It may however, be present in greatly
deteriorated yeast, but is difficult to identify. Its presence
in some stinking returned ales is indubitable, but this
can hardly ever arise from circumstances that the Brewer
is able to control ; that is to say, it is not usually con-
nected with any fault in the process, or if so, the fault or
faults must be glaring indeed. Other examples of this
organism are furnished by putrid grains and decomposing
spent hops. The growth of B. butyricum appears to be
arrested by a very moderate development of Butyric acid,
but the extraordinarily powerful and disgusting smell of
the latter renders traces of it plainly evident. If, as in the
case of B. lactis, the acid produced is neutralized by chalk
or marble, as formed, it gives rise to a large quantity of a
corresponding salt, calcium lactate or butyrate as the case
may be. Small quantities of either Lactic or Butyric acid
i -5% of the former and -05 % of the latter retard alco-
holic fermentation.* The figures if correct show, that
butyric acid exercises a far more powerful effect than lactic
acid. Acetic acid occupies an intermediate position in this
respect, as '5 / retards alcoholic fermentation.* It is
* Marcker : " Spiritusfabrikation," p. 493, et seq.
124 The Bacteria or Schizomycetes.
probable that organisms other than B. butyricum may give
rise to butyric acid.
Synonymous with Ehrenberg's Vibrio Subtilis and Cohn's
hay-bacterium. It is usually seen as long rods, straight or
somewhat curved, the width of which is about i M and the
length from 6 ju upwards [Plate X., Fig. 8.] In a free
growth the rods exhibit wavy and other movements, being
provided with a flagellum at each end. They enter readily
into the sporulating condition, as mentioned earlier in the
A pure growth of Bac. Subtilis may be obtained by
raising an aqueous decoction of hay to boiling, plugging
the flask with cotton wool, and putting aside in a warm
place ; the spores of Bac. Subtilis survive the treatment.
There can be little doubt that this organism is found in
association with beer and yeast, as the result of an improper
process. It is to be seen in racking beer sediments,
barms, forced ales and returned sour ales, and the motile
form may be sometimes observed. We have seen one or
two doubtful cases of sporulation in forced ales. According
to Cohn the organism produces butyric acid, but this has
been disputed by other observers : it seems to us probable
that lactic acid is one of its products and possibly butyric
acid under exceptional conditions; but there is no active pro-
duction of either in beer. The presence of the organism in
beer is no doubt connected with the following conditions :
a. Direct aerial contamination, especially in the autumn,
when the air is teeming with germs.
d. Uncleanliness of plant and process generally.
c. Deteriorated store yeast and a faulty process, including
wrong temperatures, etc.
It not uncommonly appears in quantity in some
The Bacteria or Schizomycetes. 125
breweries during the summer and autumn, and must be met
with extra care, and attention to salient points like those
Forced samples of ale sometimes exhibit "fields"
swarming with this organism. In these cases it is rather
curious to observe that there is not always a degree of
acidity corresponding with the growth, the deficiency of
oxygen may have a connection with this ; its appearance
would, nevertheless, cause one to be very suspicious of the
stability of the beer.
Discovered by Cohn, occurs in long or short, but very
broad cylinders or threads, 2 n broad, and in a free growth
as much as IOM long. [Plate X., Fig. 9.] It is found in
certain infusions, such as of white-of-egg. We have
obtained it as a fortuitous growth in gelatine cultivations, in
which it formed liquid cavities. It is occasionally to be
found in beers and yeast, in which case we usually ascribe
it, for ascertained reasons, to dirty vessels and pipes. It
does not appear to grow in beer, at least to any extent, and
may, we think, be regarded simply as an index of unclean-
liness. In some cultivations it seems to differ comparatively
little in form from B. Subtilis ; it should however, we
believe, be regarded as an essentially different organism.
Occurs in long threads, which are sometimes of great
length, and twisted on themselves. [Plate X., Fig. 10.]
It is found in liquids such as putrefying sweet wort, etc.,
and in decomposing masses such as the slime that collects
in wort- and water-pipes, etc. We have seen it in racking
beers, into which it probably found its way from dirty
vessels. It is possible that it is only a particular form
of Bac, subtilis.
126 The Bacteria or Schizomycetes.
SPIRILLUM TENUE AND SPIRILLUM UNDULA.
The spirillum forms, though common in rapidly putrefying
liquids and moist masses, are however, in our experience,
uncommon in connection with Brewing. We have seen
Sp. tenue in returned sour ales, and once or twice in
forced samples ; and both forms in spontaneously decom-
posing sweet wort, and in waters treated by Heisch's
test. Spirillum undula we have also seen in putrid grains,
and slime from pipes and dripping water-taps. The
morphological differences between Sp. tenue and Sp.
undula are so very slight, that many observers regard
them as the same species. Plate X., Fig. n, represents
Sp. tenue, which is about i /* thick, and 4 15 n long.
The same plate, Fig. 12, shows Sp. undula, about 1.4 ju
thick, and 8 12 /u long ; it has wider spirals than Sp. tenue,
and an active movement, at times, by means of flagella.
A few other kinds of bacteria have been observed by
Hansen* as appearing in malt worts exposed to air
infection. They are
Bacillus ruber (Frank.)
,, fusiforme (Warming).
,, Carlsbergense (resembling B. butyricum).
They do not appear to us, however, to call for more than
We will now touch briefly on the subject of Antiseptics
from the general point of view. The substances most
noxious to bacteria seem to be Chlorine, Bromine, and
Mercuric Chloride, especially the latter ; they are of
course quite inapplicable to Brewing. Amongst the less
powerful but still effective antiseptics are Salicylic acid
and Sulphurous acid, with their various combinations.
Sulphurous acid combined as bisulphite of lime is, as is
* Meddelser fra Carlsberg Laboratoriet. Andet Hefte, 1878, p. 73.
The Bacteria or Schizomycetes. 127
well known, of high value for cleansing purposes in the
brewery, and also, but to a less extent, in the makings.
Other bodies exercising a, well-marked antiseptic action
are alcohol, common salt, alum, various metallic salts,
tannin, creosote, carbolic acid, lime water, and thymol. One
or two of these are naturally associated with beers, the
remainder, however, are not so connected, and would in
the majority of cases be quite unsuitable for cleansing
plant : we mention them as having a specific effect on
bacteria generally. Moulds, generally speaking, resist
the action of antiseptics more than bacteria, and bacteria
have greater resisting powers than the saccharomycetes.
We will bring this chapter to a close with a few hints as
to the examination of beers and yeasts for bacteria. Aver-
age samples should in all cases be obtained, and many
" fields" should be examined, the slide being moved syste-
matically so as to constantly present fresh parts to view.
The results of observation should be noted down, so as to
specify in some way the number and kind of bacteria present;
actual counting is sometimes out of the question. Note
book terms may be applied to beer and yeast as follows:
Clean. Moderately clean. Not very clean. Not clean.
Whilst the quantity of bacteria may be represented
arbitrarily by the numerals i, 2, 3 ; anything over the
standard of 3 being marked, Quantity. In the note-book,
positions may be allotted to different kinds of bacteria.
The following entry serves as an example :
Beer -g Not very clean, i o i uK
which we should interpret : One of Bacterium lactis per
two or three " fields." No Bac. subtilis^ and i Bacillus
ulna: the verbal description of course speaks for itself.
As brewing processes usually vary so much in their state
of cleanliness as regards bacteria, such a means of record
as we have tried to describe must be adjusted or made
relative to each process, the results not being exactly
THE FORCING PROCESS,
WE have already in Chapters III. and IV. made
frequent reference to Pasteur's classical researches
into the fermentation of Beer and Wine, and we now
wish to explain how the methods first employed in those
researches, may with advantage be practically applied by
the scientific brewer to the regular examination of his
Briefly, Pasteur's method of investigation may be said
to consist of experimental fermentations with fermentable
liquids which had been completely sterilized by repeated
boiling in glass vessels, whose outlets were either shut off
from the air, or so plugged with cotton wool as only to
admit thoroughly filtered air. When the liquid in
the glass vessels was found to remain free from change, it
was inoculated with minute portions of the purest growths
obtainable by the methods employed. We thus purposely
define Pasteur's pure growths, because Hansen's recent
work has shown conclusively that the separation of the
Saccharomyces by shape alone is impossible, and it is
therefore more than probable that many of Pasteur's
experiments were conducted with more than one variety
forcing Tray in working order,
(from a photograph]
BE.MROSZ- & SONS. LIT'.
The Forcing Process. 129
One of the chief results of Pasteur's work was, that
working under the conditions above-named, his fermented
liquids usually remained free from Bacteria, and therefore
free from those acid changes which under less favourable
conditions are found to accompany, or more correctly
speaking follow, alcoholic fermentation. Pasteur had
very carefully investigated some of these Bacteria, more
especially those producing Acetic and Lactic acids, and it
was the consideration of his published works on Vinegar
and Wine* that induced the leading Burton chemists to
apply his methods of investigation to the systematic
examination of Beer, prior to the publication of the well-
known work " Etudes sur la Biere," in i876.f One of
the most earnest and indefatigable workers in this direc-
tion was Horace T. Brown, and he may be said to have
first systematized the method of beer examination by
It is to the consideration of this method of testing the
keeping qualities of ales and worts depending as it does
so materially on the use of the microscope that we intend
to devote this chapter ; and in the first place we will
describe the piece of apparatus employed first in Burton,
and now generally used throughout England, known as the
Forcing Tray [Plate XL] It is an oblong vessel, made
preferably of copper ; the size varies somewhat, but we
find the following dimensions very convenient : 2 ft. 9 in.
by i ft. 9 in., and 3 in. deep ; the upper surface may be
turned up about \ in. all round to form a rim.
The want of attention to certain details, and to the fitting
of various accessories, may very considerably vitiate any
results obtained by the use of this apparatus ; so that we
shall now describe in some detail the apparatus itself and
the method of using it, before entering upon a description
* Etudes sur le Vin, 1866, and Etudes sur le Vinaigre, 1868.
f Translated by Faulkner and Robb, 1879.
130 The Forcing Process.
of the varied microscopical observations, which are the
principal sources of information gained by its use.
It is advisable to have an oblong sheet of thin copper or
block tin, brazed or soldered on the under side of the tray,
in order that the gases given off by the burner used for
heating it, may not corrode the actual surface of the tray.
When this protecting piece is found to be seriously corroded
it may be easily replaced by a fresh one. Inside the tray
it is usual to have another sheet of copper covering the
central part, and supported about \\ inches from the bottom;
this is called the Disperser, and extends to within about 3 or
4 inches of the sides of the tray ; its purpose is to prevent
the water directly heated by the burners rising at once to
the top of the tray, and so causing an unequal heating of
its upper surface. A fair sized tubular opening should be
provided for filling the tray, and this may be loosely
covered by a cap, or plugged with cotton wool. A tap
or bib-cock may conveniently be fixed at one end or
underneath for emptying when repairs are required.
The heating, which is all important, should whenever
possible be with gas, as the regulation of any other source
of heat is difficult. A piece of ordinary f-inch gas-piping
about one foot long, with six porcelain-tipped nipples (size
No. 2), screwed in at equal distances, is as suitable a burner
as any (see illustration), and should the tray be square the
gas piping may with advantage be bent into a circle. This
burner is fixed so that the surfaces of the nipples are not
less than three inches from the plate on the underside of
the tray, and it is directly connected with the Regulator by
india-rubber or " composition " tubing.
The usual form of Regulator is that known as Page's
(Fig. 24), which may be described as follows :
The bulb B and about an inch of the tube A is filled
with clean mercury, which may conveniently be done by
pouring small quantities of mercury at a time, into a small
The Forcing Process.
cone of stout writing paper with a good sized pinhole in
the point, placed in the upper end of the tube A, or in the
side tube K ; closing the opening not used, with the finger.
The regulator is now placed in a small flask of water on the
tray, as shown in Plate XI.
The tray being quite filled with water at a temperature
sufficient to keep the thermometer on the tray about two
Fig. 24. Fig. 25.
METAL GAS CONNECTION.
degrees below the required temperature, a pint or two of
water may be drawn off to allow for expansion. The
sliding tube C of the regulator is now connected by india-
rubber tubing to the gas main, and the outlet tube K
similarly connected to the burner ; gas passes to the latter
down the quill tube D, a small amount, sufficient only to
keep the burner from going out, going direct through the
pin hole S, the main portion through the end T
which in some cases is bevelled and up the tube A into
K. Under these conditions too much gas passes to the
burners, and the temperature of the tray rises. When the
132 The Forcing Process.
thermometer on the tray indicates the required temperature
(about 80 F.), the sliding tube C is pressed down until the
lower end of the quill tube T just touches the surface of
the mercury. If too much gas is thus cut off, the tem-
perature of the tray falls slightly, the mercury in the
regulator contracts and falls in the tube A, thus allowing
more gas to pass through the quill tube at T, and so
to the burners.
In an older form of this regulator, which is somewhat more
reliable with a large amount of variation in the gas pressure
(frequently the case in large works like breweries), the small
hole in the side of the quill tube is replaced by a metal H
piece (Fig. 25) with a tap in the centre ; the two lower
ends are connected respectively with the main and the
burner, and the two upper ends with the quill tube and
the side tube of the regulator. In use, the tap in the H
piece is opened sufficiently to allow the same amount of
gas to pass direct to the burner, as does the small hole in
the previously described instrument ; the remainder has first
to pass through the quill tube of the regulator, the only
passage being through the end T, which is directly con-
trolled by the expansion and contraction of the mercury
in the bulb. A modification of this arrangement is shown
in Plate XL, the main gaspipe forming practically one
limb of the H piece.
The flasks hold preferably about 120 cubic centimetres,
and we find the pattern given in Fig. 26 more satisfactory
to work with than any other ; the old form with loose side
tubes to be joined by india-rubber tubing being the cause
of much waste of time, and therefore not to be recom-
mended. In cleaning these flasks the greatest care must
be taken to put no pressure on the side tube, as it is very
liable to break off: well made flasks, however, stand
ordinary handling well, and we have many that have
been in regular use several years.
The Forcing Process. 133
It will be as well now to consider the precautions
necessary when collecting samples :
Beer samples are best taken from the racking vessel :
when beer is racked direct from
cleansing casks, the samples may
be taken from them or from the
trade casks as soon as filled.
Ordinary 10 oz. stoppered bottles
are quite suitable for collecting these
samples, and may also be used
for obtaining the sediment of the
racking sample to be microscopically
Each bottle should be carefully
cleaned, and first rinsed out with the beer to be sampled,
before filling ; it should also be labelled as soon as taken.
With regard to cleaning : The bottles should be
thoroughly rinsed round with a solution of caustic soda,
then well washed out and allowed to drain neck downwards ;
forcing-flasks may have a few cubic centimetres of a dilute
solution of caustic soda boiled in them, followed by a
thorough washing in clean water; draining as in the case of
the bottles, taking place neck downwards.
A good draining-rack for forcing-flasks is made by
stretching two stout copper wires about \\ to 2 inches
apart over the sink. It is well to fill the forcing-flasks
within twenty-four hours of taking the sample, and before
filling they should be washed out twice with the beer to
be sampled. When filled, the neck of the bottle is closed
by a small India-rubber stopper which has first had some of
the beer poured over it. It is better to leave about \ inch
or so between the level of the beer in the neck of the flask,
and the side outlet.
When placed on the tray, the side tube should dip not
less than \ inch into mercury conveniently placed in small
134 T/ le Forcing Process.
beakers, each of which will take five or six flasks standing
round it [Plate XL] Another method is to have the side
tubes dipping into little troughs of wood or porcelain, filled
with mercury ; this allows of double rows of flasks on the
tray, and utilizes a larger proportion of its surface.
The thermometer on the tray may be placed in a flask
of water with some mercury at the bottom, so that the
temperature indicated is practically that to which the beer
in the forcing flasks is subjected.
As the object of these experiments is to see how far
a beer may be expected to withstand the variations of
temperature to which trade casks are subjected, the tem-
perature at which these samples are maintained is in excess
of that usually met with, and the growth of Bacteria and
forms other than healthy Saccharomyces is thus consider-
The thermometer on the tray showing a constant
temperature of 80 F., and the samples duly placed, certain
observations may be made during the first few days ; thus
it is useful to note how long the beer takes to drop bright ;
if a large quantity of gas is given off quickly, or if the
beer remains a long time before secondary fermentation
Next, as to the length of time it is desirable to submit
beers to this process. For Stock ales and it is chiefly for
this class of beers that the method of examination is of
value we find three weeks the shortest time practically
useful, and where possible should advise four weeks.
When the flask is taken off the tray, the appearance
of the sample should be noted, whether bright or not, and
especially if there be any growth on the surface of the
liquid. The liquid when cool should be decanted, and the
specific gravity taken with a small saccharometer ; the
taste, amount of acidity, and any peculiarity of flavour are
The Forcing Process. 135
The sediment should be shaken up with the few drops of
beer remaining in the flask, * and a small drop examined in
the usual way under the microscope. The chief points to
be observed in the microscopic examination of these
samples are :
i st. The condition of the original yeast (S. cerevisiae).
2nd. The amount of new yeast.
3rd. The variety of secondary and wild forms present.
4th. The presence or absence of Bacteria.
5th. The forms of Bacteria present.
The inter-comparison of such observations will lead
anyone very quickly to form an opinion as to the relative
keeping quality of the beers examined, and it is chiefly this
relative value that is of service to the practical brewer, as
it enables him to decide as to the order in which to send
out his stock.
On Plate XII. may be seen examples of forced beer
sediments, and it will be noted that the relationship of
Saccharomyces to Bacterial forms is variable. From what
we have already stated under the separate headings of the
Bacteria and Saccharomycetes, it will be concluded that
there must necessarily be a great diversity of appearance.
We have found it most convenient to group all forced
samples into three classes, I., II., and III., and two sub-
classes I. to II. and II. to III. All beers that taste sour
when they come off the tray, and that have a high
acidity (that is, above the normal but not actually sour),
together with a deficiency of new yeast cells, and
swarming with short and long Bacterial forms, we mark
Class III., and should not consider it safe to keep such
beers over six weeks from rack, unless treated with
some antiseptic. Beers that have no objectionable pecu-
liarity in flavour, and that when examined exhibit a fair
* Occasionally these sediments are very dark, almost black ; we have reason to
believe this is due to a decomposition of the lead glass of which forcing flasks are often
made, and the production of Sulphide of Lead, which is taken up by the cells.
136 The Forcing Process.
amount of new normal yeast forms, yet containing a
considerable number of Bacteria, we mark Class II., and
should advise them to be put into the trade at an early
date, anticipating difficulty with such beers if kept over
two months. Sound-tasting beers exhibiting only normal
secondary forms of yeast, or no new yeast, and free from
Bacteria, or containing only a few Lactic or Bacillus forms
in each field, we should mark Class I., and expect to stand
well through the summer. Beers that on examination
appear too good for Class II. and not good enough for
Class I. we mark I. to II., and the same applies to the
The six examples given on Plate XII. are fairly typical
of this arbitrary but convenient classification :
Fig. i. A normal clean residue of S. Cerevisse ; the
large size of some of the cells is probably a result of
the forcing tray temperature = Class I.
Fig. 2. A mixed growth of wild yeasts, chiefly S.
Pastorianus and S. Ellipsoideus = Class I. to II.
Fig. 3. An active growth of what is probably Pasteur's
Caseous ferment (S. Coagulatus I.) in a form it is not
infrequently met with in forced samples = Class I. to 1 1.
Fig. 4. Few ferment cells, and a vigorous growth of
Bacillus subtilis, in the form most frequently seen in
these deposits = Class II.
Fig. 5. A few yeast cells and Bacteria and a con-
siderable growth of Sarcina, probably Pediococcus
acidi lactici = Class II.
Fig. 6. Hardly any yeast growth, and swarming with
rod and Bacillus forms, probably B. lactis and B.
subtilis. If not above normal acidity = Class II. to
III. If markedly acid = Class III. '
The gas supply should be of a uniform and steady
character, as one of the effects of the gas going out, and
the tray consequently falling in temperature, is that mercury
"Forced Beer'' sediments
West , Newman & Co. Sc.
The Forcing Process. 137
is driven back into the flasks, especially in the case of
flat ales. In so far as the effect of the mercury itself is
concerned, we have some reason to believe that it acts as
an antiseptic, deterring the production and growth of
Bacteria, and possibly of Saccharomyces ; but it is a dif-
ferent thing if air enters as well, as a clouding of the beer
and film growth on the surface, together with acidity and
occasionally ropiness, may ensue, and the experiment be
We have also found the tray a suitable apparatus for
testing the tendency of malt extracts to become acid, by
comparison of the amount of acidity formed in a given
number of hours from 72 to 120 with the normal acidity
of the malt extract ; a free exposure to air and consequent
infection being first permitted. We are of opinion that a
useful factor in the determination of the quality of various
samples of malt is thus obtained.
Another useful purpose to which the forcing tray may
be placed is testing samples of water for purity by the so-
called Heisch's test; in so far as the amount of Phosphates
in a water is indicative of contamination. (See Chapter X.)
THE ANATOMY OF THE BARLEY-CORN,
IN the selection of a sample of barley, the Brewer or
Maltster is guided by various features that are visible
to the unaided senses, such as the general appearance of
the corn, the nature of its skin and the state of the starchy
portion ; but to comprehend the minute internal and
external structure of the seed, we must apply a somewhat
closer inspection by means of the microscope. Let us
consider first in brief the more general attributes of the
Barley-corn. We have a spindle-shaped body, somewhat
more pointed at the germinal end, enveloped by a strong
skin or husk (the Palece), which is fairly smooth and flat
on the dorsal side, but considerably wrinkled and
rounded on the other the ventral. The dorsal side is
traversed from end to end by five small ridges, caused by
vascular bundles in the husk, and this latter is drawn down
into a furrow, which extends along the corn on the ventral
side. On looking closely into this furrow at the germ end,
we discern in the perfect corn a small spike or bristle,
which on being separated and placed under the microscope
shows itself to be a bundle of fibres packed very closely
together, with other small fibres or hairs standing out on all
sides, presenting under a low power the appearance shown
The Anatomy of the Barley-Corn. 139
in Fig. 27 a. This is called the Corn-bristle. Now if,
instead of breaking off this bristle, it is carefully dissected
out under a hand-lens, from a steeped corn, or one that has
been on the "floors" some days damp corns being far
more easily dissected than dry ones it may be removed
together with certain small processes attached to its base.
To do this a sharp penknife or the sharpened needles
previously mentioned may be employed, and the outer
coating removed according to Fig. 28, the dotted lines
being those of incision.
On examining this structure under a moderate power it
presents the appearance indicated in Fig. 27 b b, the
portions so marked are known as Lodicules. They are oval
transparent processes, somewhat resembling a hand with out-
stretched fingers, the fingers being hairs or spines, similar
to those on the bristle itself. The attachment between the
Lodicules and the bristle is complete at c, where they unite
with the inner Pale^e. Both these portions appear to be
remnants of the flower of the Barley.
Now it is a property of minute tubes and bundles of
fibres having small interstitial spaces, to absorb liquids
freely, and this power is called Capillary attraction ; it may
The Anatomy of the Bar ley -Corn.
be seen to advantage if a glass tube be heated in a flame
till it can be puljed out into a thread, and portions of this
thread dipped at one end into a coloured fluid, such as red
ink. The passage of the fluid up the capillary tube is
plainly seen, the height to which it rises being determined
by the diameter of the tube and nature of the liquid.
It has been argued* that the Corn-bristle and Lodicules
together constitute an arrangement adapted for the capillary
absorption of liquids, and it is on the face of it probable,
that whether destined for this purpose or not, they are able
to absorb water and carry it into the corn. It is however,
evident that absorption can go on without the intervention
of the bristle, as corns from which it has become detached
behave in the usual way on steeping ; the Lodicules, being
protected by the husk, may nevertheless still convey water
to the corn.
These views as to the function of the bristle and
lodicules have been definitely refuted by recent researches,
and experiments of our own indicate that the corn will take
up water equally well at either end.
The husk of the Barley-corn, consisting of two leaf-like
bodies, known as the Palece, may next be taken into
* "Die Anatomic des Gersten Kornes," Lorenz Enzinger.
Port/ on of Pa/ BO, x J f l
F, 3 . 4.
Outer /cuer of PU/&O,
Disintegrated fibres of Pcu/eoe
O MATTHEWS . DEL.
BMfiO$ & SONS.L/Tf
The Anatomy of the Bar ley -Corn. 141
consideration, and to do this effectively it is better to
separate portions of and digest them for some days in
warm dilute acid, dilute Caustic alkali, or Bromine water;
they are then easily dissected and will be seen to
consist of two distinct layers of cellulose fibres which when
"in situ" lie in the direction of the length of the corn.
This skin, magnified to a very moderate extent, is shown
on Plate XIII., Fig. i. The upper layer consists of toothed
or corrugated fibres (Fig. 2), the corrugations dovetailing
together as in Fig. 3, the round portions occurring at
intervals being, as it were, pegs which connect the two
layers, the lower of which is more distinctly fibrous, the
fibres interlacing as at Fig. 4. Both layers are indicated
in Fig. i in the position they naturally occupy. The
whole forms a very strong and dense layer, yet possessing
sufficient elasticity to meet the swell of the corn on steeping.
The dorsal Palea, which in the unthrashed corn is
continuous with the so-called " beard" or awn, just
overlaps the ventral one at an equal distance on either
side of the furrow.
The Germ which in sound corns becomes the young
barley plant, lies beneath the inner transparent skin on the
opposite side to the corn-bristle, and when the Palea is
removed, appears as a small waxy yellow substance.
Beneath the Paleae are two coats or skins, the one*
immediately underneath, called the Pericarp, is shown in
Plate XIV., Fig. i. It is a very fine integument, and
exhibits when magnified a nearly transparent cellular
structure, the cells having a general tendency to a
rectangular form. The cells appear for the most part
to be separated by minute spaces, and occupy a position
with the longer axis of the cell in the same line as the
longer axis of the corn. It is pretty certain that this
second skin, by the nature of its structure and position,
allows liquids to pass freely from end to end of the seed,
142 The Anatomy of the Barley-Corn.
and can take up water directly at either end where it is, so
to speak, fractured by separation from the point of
attachment to the ear and the "awn" respectively. The true
covering of the seed or third skin, known as the Testa,
is, like the Pericarp, a very fine layer of cellular matter ;
the cells in this case having a decided tendency to a
prismatic form, their longer axis being at right angles to a
line drawn from end to end of the corn [Plate XIV.,
Fig. 2]. Here also the cells are separated by minute
spaces which doubtless act as capillary tubes, and convey
moisture around the inner seed. These two skins can be
separated into various layers, but we consider it sufficient
in this work to describe their main features only.
ifr/The inner Palea, together with the Pericarp and Testa,
pass some way into the corn-furrow and fold there, but the
layer of cells immediately underlying the testa passes con-
siderably further into a central channel which extends the
whole length of the corn, and is well seen in Plate
XVI., Figs, i and 2, which represent transverse sections,
Fig. i before germination has commenced, and Fig. 2
when it has proceeded some days. The channel thus
formed completes the arrangement for the moistening of
the interior of the seed, and for the circulation of liquids
during the process of germination ; for being in direct com-
munication with the absorbing tissues it can become filled
with the water conveyed by them; and moisture being thus
applied very completely to the starchy portions of the corn,
all the inter-cellular spaces become filled up.
Having now considered the outer coatings, let us direct
our attention to the inner seed, and refer to the longitudinal
section of the barley-corn given in Plate XV. This section
is supposed to be through the furrow.
A, represents the coatings generally, which have been
already sufficiently described. The starchy portion or
Endosperm B, is seen to be situated above the germinal
Fig. I. Pericarp
Fi g <*>. Diagram Section,
p.s Paleou Superior, p.i Palea inferior
al. A /euronG layer. e.n.d. Endosperm.
e.m. Embryo d. Basal bristle
p. Pericarp ouw. Awn, i. Testcu.
SflrfiO$ & SOf/S.L/TP
Sect /on of a Bar/ey Corn in the p/ane of the
ax/s and trough She -furrow.
Reduced from C.
D Corn bristle
F. Pigment siring
6 1 A/eurone layer
62 Starchy mattet
6s Empty cells
C Germ 1 - pourts
ce A cr asp/re
B/*#0$ & SOf/S.l/r?
From a Photograph
Transverse sections of Barleycorn
The Anatomy of the Bar ley-Corn.
parts or Germ C. The Endosperm and the main bulk of
the Germ are bounded by a peculiar layer known as the
Aleurone cells, as well as by the Testa and Pericarp (see
Plate XIV., Fig. 3). These cells, some of which are
shown highly magnified in Fig. 29, contain finely granulated
proteid or nitrogenous matter, and small spherules of fat
or oil ; it is not clear what their immediate function is,
but seeing that they are in contact with the starch cells of
the Endosperm and the great bulk of the Germ, they may
take some active part in the transfer of food from the
former to the latter.
The Endosperm itself is a mass of Starch cells, of
which there are two kinds in the Barley-corn, large and
small, intermingled with irregular and spherical particles
of nitrogenous and mineral matter ; the whole contained in
radial compartments of cellulose, and forming a store of
food stuff to supply the germ until it is grown sufficiently to
enable it to draw nourishment through its roots and leaves.
On disintegrating a portion of the Endosperm and
examining microscopically, the larger starch granules are
144 The Anatomy of the Bar ley-Corn.
easily distinguished, and can be rendered even more
distinct by staining with a little of the weak Iodine
solution (see Appendix), a drop or two being applied to
one side of the cover-glass, whilst a small piece of blotting
paper is held against the other side ; the Iodine solution
is thus carried across under the cover-glass. The starchy
portions assume a deep blue tint, and portions of matter
faintly coloured, or not coloured at all, are something other
than starch : owing to the diffusion of a small amount of
soluble starch in the corn, the non-starchy portions some-
times exhibit a shade of blue when thus treated.
The two kinds of Starch are shown in Plate XVII.,
Fig. i. With oblique illumination obtained by suitable
openings in the diaphragm, or other means such as
staining with a solution of Chromic acid, concentric lines
are rendered visible on the starch granules, but they are
much more plainly seen on some other kinds of starch,
more especially Potato starch [Plate XVII., Fig. 2],
Examples of wheat, maize, and rice starches are given on
the same plate, and it will be seen that there is a considerable
variety in appearance.
The germ proper, which in the dried barley-corn forms
only a very small portion of the whole (about ^V), is
separated from the Endosperm by a sheath called the
Scutellum [Plate XV.], consisting of a dense Epithelium
of " palisade-like cells," upon which is usually found a layer
of compressed empty cells from which the starchy contents
have been dissolved.
Immediately underlying the upper end of the Scutellum
is the Plumula or Acrospire which, as germination proceeds,
gradually increases in size by cell multiplication, forces
its way beneath the Testa, and eventually emerges from the
upper end of the corn if its progress be not checked by
some such means as that adopted in malting ; at the same
time the embryo rootlets expand, separate, and descend
PL A TE2VJT.
J.E. WRIGHT DEL
BMflOS & SONS
The Anatomy of the Bar ley-Corn. 145
through the base of the corn. The number of rootlets
varies according to the kind of barley, some barleys
having only three, others as many as eight rootlets. As
before stated the Endosperm contains the supply of food
required by the germ, and the alteration of this supply
from the almost insoluble non-diffusible state in which it
originally exists, into a liquid that can be easily conveyed to
the growing germ, is a point of very considerable chemical
and biological interest. Horace T. Brown, in a most
interesting paper on "A Grain of Barley," * says that
40 % of the total reserve nitrogen originally present in the
Endosperm, passed to the young growing plant in eleven
It has been noticed that during the growth of the
Acrospire, the starch cells in its immediate vicinity are
strongly influenced by some solvent, probably akin to
Diastase,- which dissolves away portions of them, creating
an appearance called pitting. Two such pitted or eroded
granules are shown in Plate XVII., Barley Starch. Of
the soluble matters thus formed, a portion probably goes to
nourish the germ, and it is not improbable that an active
circulation is kept up by means of the various enveloping
coats of the corn and the central channel, whereby a
modification of the contents is continually going on so
long as the corn is kept moist, the end result being the
formation of fermentable sugars and diastase. Interesting,
however, as these chemical changes may be, it would be
plainly out of our scope to enter more fully into them,
our object having been to describe the apparatus by which
they are effected and which is beautifully adapted for the
In this sketch of the anatomy of the Barley-corn we have
not attempted to go into detail as to the mode of develop-
ment of the corn in the ear, nor to enter into considerations
* Transactions of the Burton Natural History and Archaeological Society, 1889, p. 108.
146 The Anatomy of the Bar ley-Corn.
that would appear to be purely of Botanical interest ; if,
however, the reader would wish for further information he
will find the subject exhaustively treated by Johannsen,*
and lately by Holzner and Lermer,t who have practically
worked out the minute anatomy of the grain. A concise
epitome of this work is given in the paper by H. T.
Brown, just referred to. We might add that it is not only
useful but instructive for the student to make sections of
the Barley-corn at different stages of its growth, and
suggestions as to the preparation and permanent mounting
of these sections will be found in the Appendix.
* Carlsberg Report, Vol. II., part 3.
t Beitrage zur Kentniss der Gerste.
HOPS, SUGAR, AND WATER.
IN connection with hops there is comparatively little
scope for the use of the microscope, seeing that the
salient features of any given sample are, with the necessary
experience, taken in by examination with eye and hand.
We have in Chapter VI. alluded to the identification of
moulds on the surface of hops, and we will now devote a
little space to the consideration of one or two points in
connection with the structure of the hop-cone, also known
as the catkin or strobile, which, botanically considered,
consists of a number of small bracts, with two ovaries at
their base, each being accompanied by a rounded bractlet.
Both bracts and bractlets enlarge greatly during the
development of the ovary, and form, when fully grown, the
membranous scales of the strobile.
The microscopic structure of the leafy portions of the
Hop-cone has no direct interest for the Brewer apart from
any appearance of mould, ravages of blight, or anything of
a purely superficial character ; for the extractible substances
that are of value in beers do not reside here, they are
found in the " condition" or "lupulin." If the golden
grains forming the latter be examined under a very
moderate power, they are seen to consist of little vesicles
148 Hops, Sugar, and Water.
or capsules, the form and structure of which is rendered
quite plainly visible 'if their contents be exhausted by
immersion in a small quantity of hot alcohol before
placing on the slide. Fig. 30 shows the symmetrically-
shaped capsule in its ordinary position at the base of the
leaflet or bract. If a few of the capsules in their original
state from new or recent hops, be broken on a glass
slide by pressure on the cover-glass, the oily and resinous
contents may be seen surrounding the broken capsule.
This escaped matter includes the Hop-oil or Aroma,
Hop-bitter proper, Resin, Fat, and astringent matter
of the nature of Tannin. As hops ' age,' the contents of
the capsules become gradually less oily and more highly
coloured, till at length, in hops that are two or three years
old, only hard dark-coloured matter is left, where formerly
was a golden oily substance ; the Brewer well knows the
changes in the nature of the Hops accompanying such
appearance. Interspersed amongst the capsules proper are
found smaller vesicular bodies, consisting of four to eight
cells grouped together, very much enlarged at the upper
end ; these vesicles are usually colourless. The nature of
their contents has not, so far as we know, been definitely
ascertained : in comparison with the large capsules, they
would appear to be of quite secondary importance from a
brewing point of view.
It is astonishing what a diverse collection of objects
Hops, Sugar, and Water. 149
may be removed from Hops by shaking them up several
times with water, pouring the water off quickly, and by a
fractional separation dividing the lighter objects from the
heavier. Most hops thus treated show Bacteria, Crystals
(probably Malate and Oxalate of Lime), Cells of Sac-
charomyces, Infusoria, and Protococcus. Many samples
yield Mould-spores, and some few show these last in
In Plate XVIII. are shown examples of most of these
a. Ferment cells.
d. Particles of Earth and Siliceous matter.
e. Spicules, probably part of the Hop plant.
f. Mould-spores, probably of Ustilago and some species
g. Probably Protococcus.
k. Probably Pollen cells.
i. Portions of Mould hyphse.
By treating barley in a somewhat similar manner, and
making a microscopic examination of the sediment, a
variety of organisms, etc., is exhibited, which seems to be
even greater than is obtained from hops. Plate XIX.
shows the following objects so obtained :
i. Starch cells.
2 and 4. Cells of protococcus.
3. Spicules, probably part of the corn.
5. Cells of Saccharomyces.
6, 7, 10, 13. Mould-spores (simple and compound), pro-
bably Ustilago Segetum and other species.
8, 9. Diatoms.
1 1 a. Pasteur's lactic ferment, b. Bact. aceti.
1 2 a. Bact. lactis, b. Bact. termo.
150 Hops, Sugar, and Water.
14. Pollen cells.
15 a. B. leptothrix, 6. Bacillus subtilis.
1 6. Compound spores of red mould.
The water first run off from steeping barley is a good
source from whence the above and other organisms may
be obtained ; the coarser particles should be separated by
a short settling, and the liquid may then be left to deposit
the finer particles for examination. No doubt most of
the organisms found on Barley and Hops are discernible
on other forms of vegetation freely exposed to the air
during their growth.
It will from previous considerations be obvious that
"dry-hopping" has its disadvantages as well as advan-
tages, for many of the living cells, more especially
those of Saccharomycetes, are able to, and often do set
up in Beers a characteristic secondary fermentation,
the so-called "hop-sickness," which in its early stages is
sometimes attended by a very unpleasant smell. If the
ale is inherently sound it will recover from this, but a
faultily-brewed ale may not only support the alcoholic
ferments introduced by hops giving a persistent and
awkward fret but after these have had their sway, may
have its decline hastened by the considerable addition
of Bacteria beyond those it possibly contained at Racking.
Any mould-spores introduced by dry hops would probably
remain dormant till the Beer was drawn off, but might,
under favourable conditions of growth, develop in the
dregs and help to produce a mouldy cask.
In cases where Brewing sugars do not dissolve to a clear
solution in water, and give perhaps a well defined sediment,
it is desirable to ascertain by the Microscope what this
suspended or sedimentary matter may be ; more often
than not, in the case of Glucoses or of Invert Sugar, it is
Organisms & c found in Hop dust,
J. . WRIGHT.DEL.
BF.MflOSf & SON3.1-IT'.
/ 1 *
Organisms found in basleu dust.
G.G MATTHEWS. DEL.
Hops, Sugar, and Water. 151
Sulphate of Lime left from the neutralizing ; the sulphate
being soluble to a considerable extent, and perhaps
crystallizing out in the concentrated syrup before solidifi-
cation. There is nothing particularly objectionable in this,
except that it does not indicate the most careful manufacture.
Raw, unrefined, or partially refined Cane Sugars may show
some diversity of extraneous objects, e.g., Mould-spores,
Saccharomyces, etc., and the insect Acarus sacchari is not
unfrequently met with : in the latter case it is well that we
have some confidence in the destructive action of the heat
of the boiling copper, for it would be unpleasant to
contemplate the possible survival of such organisms. Sugar
solutions may be tested as to their power of supporting
Bacteria, by dissolving one or two grams of the sugar in
250 c.c. of distilled water and putting in a clean corked or
stoppered bottle on the forcing tray for a day or two. Sugars
containing Phosphates or Phosphorus in organic combination
develop Bacteria freely, and if a perceptible amount of
phosphates be present, a Butyric fermentation will be set
up. Such a state of things as this last, though not exactly
indicating that the sugar is quite undesirable for all
purposes, would nevertheless, we think, afford good ground
for not using it in ales that were destined for " stock."
The microscope may be employed to ascertain the nature
of the organisms that have developed in the solution treated
The method of examining sugars just mentioned leads
us to Heisch's test for potable waters, of which it is a
modification. It is performed by taking about 250 c.c. of
the water to be tested, and adding to it i to 1*5 grain of
pure re-crystallized Cane Sugar. The bottle containing these
is put on the Forcing Tank, and the appearance noted at
different intervals during several days. Some waters remain
quite clear, others become opalescent or milky, whilst those
of the worst class go turbid and smell strongly of Butyric
152 Hops, S^lgar, and Water.
acid. The microscope will show the nature of the Bacteria
present. The test, according to Prof. E. Frankland,
indicates phosphates in the water, and this contention has
been sustained by one of us in a series of experiments on
a great many samples of water, * and as a rider to it, the
fact has been established that Butyric fermentations occur
in the waters containing most phosphates, other marked
signs of contamination being at the same time afforded
by chemical analysis.
Let us now speak of the suspended matters frequently
contained by Brewing and other waters: Besides mere
earthy matter, we not unfrequently have to deal with
a variety of organisms, including Bacteria, Moulds, and
obviously living forms classed generally as Infusoria. The
best treatment, of a water which appears likely to yield a
sediment, is to shake up the containing vessel and pour
a quantity of the water into a glass funnel holding
about half-a-pint, closed at the narrow end by an inch or
two of caoutchouc tubing, terminating in a small glass test-
tube. After some hours settlement, most of the water may
be poured off from the top ; the little tube is then
quickly removed, and if necessary the supernatant water
poured off from it separately, so as to leave the residue in
a few drops of water only : this is shaken up and put on a
slide. Plate XX. represents some of the objects we have
thus obtained from a sample of town-supply water, which
when freed from suspended matter was by no means
a = a Diatom.
b = a Desmid, (?) in various stages of development.
c = Monads (active).
d= Earthy particles.
e = portion of a Desmid.
* Jour. Soc. Chem. Ind , July 3Oth, 1887, Vol. VI., p. 495.
Organisms ^ found in sample* of Drinking Water.
J . Wff/CH T. DEL .
Hops, Sugar, and Water. 153
f = Protococcus, in various forms.
g = Diatoms.
h = (?) Protococcus or Desmid.
i = Desmids.
k = piece of Mould growth.
The presence of these bodies may, and often does mean,
that the containing reservoir, well, or tank is in an unclean
state, and this of course ought to be remedied. The
influx of sewage matter into a well by percolation is a
rather distinct matter ; here chemical analysis is the
chief guide to the actual state of the water, but there
are no doubt interesting and instructive results to be
obtained by a Bacteriological investigation carried out by
some process of cultivation in gelatine, such as the plate
method we have already alluded to, and which has been
lately described in detail by Dr. Percy Frankland.*
As an example of organisms in water we may quote
Miquel, who found :
35 germs per c.c. in rain-water caught as it fell.
62 ,, in river water from the Vanne.
1,400 ,, ,, ,, Seine above Paris.
3,200 ,, ,, ,, below Paris.
Dr. Percy Franklandf in November, 1885, found :
1,866 germs per c.c. in Thames water at Hampton.
954 ,, in river Lea water at Chingford Mill.
Later he gives further figures representing the organisms
present in i c.c. of the London water-supplies taken under
different conditions ; the results show more especially
perhaps, how large a proportion of the organisms present
(96% to 98%) is removed by the filtration carried out by
the respective companies.
* Jour. Soc. Chem. Ind., Vol. IV., page 698.
t Ibid, page 706.
154 Hops, Sugar, and Water.
Koch holds that a good water never contains more than
150 individual mixed organisms in i c.c., and that the
presence of any number much exceeding this is suspicious ;
1,000 per c.c. rendering it unfit for drinking. According to
other observers, this seems however to be a very arbitrary
classification. Our own opinion is that this method of
testing waters is at present only of the most general
application, but that it may, as the knowledge of Bacteria
advances, become of more importance.
Seeing that to all intents and purposes organisms
contained in Brewing waters must either be killed by heat
in the water itself or destroyed later in the Wort-copper, it
is of more importance that the chemical constitution of the
supply should be ascertained, than the fact that it contains
so many Bacteria per cubic centimetre or per gallon.
Doubtless a water containing Bacteria in plenty would, in
many cases, prove on analysis to be contaminated ; but it
does not follow as a matter of course that it would be so.
Some waters, such as the Sulphur waters of certain
springs, seem to afford a very suitable plasma for Bacteria
and Microscopic fungi ; varieties of Beggiatoa are for
instance found in them, the growths being mainly long
threads from 3 to 3.5 n thick. The threads contain secreted
Sulphur in grains, and by a process of decomposition give
off Sulphuretted Hydrogen, causing the characteristic
smell of certain waters.
Impure waters standing in wooden and even in metal
tanks will, especially in warm weather, throw up a scum
of living organisms ; portions of this scum sink from time
to time, eventually forming a layer of some thickness on
A few words about the filtration of Brewery waters.
Where any slight suspended matter is merely of an
earthy character, filtration is hardly necessary, as such
waters generally draw clear in time. If the suspended
Hops, Sugar, and Water. 155
matter, however, consist of animalculae, etc., it is more
serious, and the state of the well and character of the
supply should be investigated. If the supply must be
used, an efficient filter is desirable. Amongst the best
filtering media are Coke and Spongy Iron, whilst unglazed
porcelain in the shape of the Chamberland filter seems to
perform its office most perfectly.
Although the chemical constitution of a water may be
somewhat changed by filtration, it is almost idle to suppose
that it can turn a badly contaminated water into a pure and
useful one ; at any rate, this amount of work is not yielded
by any known filter on a practical scale. It is of the
highest importance that a filter should not have its power
overtaxed or be allowed to get clogged, for water after
passage through filters in this condition, is generally rather
more impure than before filtration.
BREWERY VESSELS, ETC., ETC.
HAVING, as we believe, given due consideration to
the more direct applications of the Microscope to
the brewing process, it remains for us to speak of cases
where the instrument may be of service as accompanying
or supplementing other modes of observation.
It has already been indicated that the air constitutes
the immediate source of the organisms that may cause
serious trouble in brewing, and so long as the present
method of brewing obtains, aerial contamination may be
regarded as a constant, and must be met by all proper
precautions as to the employment of good materials and a
well-considered method, thereby reducing the risk to a
The quantity of germs floating in the air of any given
neighbourhood is as we have seen (page 109) very variable ;
depending mainly on actual contaminating influences, such
as a dense population, free exposure of decomposing animal
and vegetable matters, and prevailing dirt. Apart from
these, certain atmospheric conditions have according to
Miquel, corresponding effects, for instance :
Prolonged rain purifies the air from bacteria, washing
them into the soil ; but they are re-dispersed when dust is
Brewery Vessels, etc., etc. 157
With a high barometer the number of germs in the air is
proportionately greater, and less with a low barometer.
Less also with a decrease in the amount of moisture. The
proportion of ozone, and changes of temperature and of
the direction of the wind, also affect the number. At sea
the air is practically germ-free.
We have already had occasion to make passing
mention of a series of experiments carried out by Hansen,
to ascertain the nature of the organisms present in the air
surrounding the Carlsberg Brewery, and in the buildings
themselves.* For this purpose flasks of sterilized beer-
wort were exposed to air infection, and the following
organisms were identified, many of which are well known,
and others have been already spoken of, but we think it
desirable to reproduce the whole list.
Eurotium aspergillus glaucus.
* Meddelelser fra Carlsberg Laboratoriet, 1879 and 1882, vol. I, part 4.
158 Brewery Vessels, etc., etc.
A species of Dendrochium.
,, ,, Monilia.
,, ,, Arthrobotrys.
FORMS NOT CLASSIFIED, POSSIBLY MOULDS.
Cells like Saccharomyces cerevisiae.
Red cells resembling Saccharomycetes.
Small round cells of a "torula" form.
Micro-bacteria and Micrococcus.
Some parts of the Brewery showed more organisms than
others. An elevated temperature favoured the production
of organisms in the flasks exposed, and some of the
organisms appeared even at 42 C. (107.6 F.), but such
an elevated temperature more especially favoured Myco-
derma Vini. Bacteria were particularly favoured by a
temperature of 26 C. (78.8 F.)
A practical application of these researches has been
made by washing and purifying the air entering the
Brewery Vessels, etc., etc. 159
fermenting cellars of the Alt Carlsberg Brewery. The
filtering and cleansing medium is brine, through which
the air is allowed to pass, leaving behind the germs it
In cases where fermenting worts were aerated by
pumping machinery, we have seen filtration carried out
by tying thicknesses of canvas over the inlet for air; or the
air may be filtered through a kind of cushion containing
cotton-wool not too tightly packed.
From foregoing matters it will be plainly recognized that
from the time that worts on the " cooler" fall below a
certain temperature, fully developed organisms finding their
way into such worts, may retain their vitality unimpaired.
The spores of some bacteria and probably of moulds,
would resist even the highest temperature of "cooler"
wort. When the opportunity arrives, these air-borne germs
take effect, and such an opportunity is provided when the
vitality of the yeast has been lowered by some of the
various possible causes which we shall touch upon in the
next chapter. A healthy, vigorous fermentation may be
considered as precluding the development of disease
organisms, and where the materials and process are good,
and the pitching yeast clean that is, free from bacteria
and wild yeasts air-borne germs are of little consequence,
unless the air of the particular locality conveys an
overwhelming number. As regards spores of moulds or
bacteria surviving the boiling in copper, or introduced
from the air, it may be said that malt actually having
mould on it, is likely to be a cause of far more trouble
than these, as it carries in itself the results of mould
deterioration. In the same way a contaminated yeast
carries its character stamped on it, and will, apart from the
contained organisms, prove an inferior ferment.
Floors on which beer or wort is being constantly spilt
are, if neglected, likely to get into a most offensive condition
160 Brewery Vessels, etc., etc.
and may engender bacteria freely. Hot water is doubtless
the best agent for cleansing wooden floors, and it is a good
thing to occasionally follow up its use by mopping over
with Bisulphite of lime. Old brick, cement, or tile floors
that have become cracked or broken-up by age, may
harbour all sorts of abominations in the way of bacteria,
mould, etc. Renewal is about the only cure, but till this
be effected bisulphite of lime or sulphurous acid may
mitigate the evil.
The walls of fermenting and cleansing rooms should be
kept in as good order as possible : no damp, mouldy, or
clammy places should be allowed, but a clean surface
free from dust and dirt provided. The surface of walls at
the back of fermenting vessels, especially of '"squares,"
sometimes gets into a deplorable state of dirt, or perhaps
the wordy/// more correctly expresses the condition. This
is usually as much a fault of construction as anything else,
the places spoken of being almost inaccessible.
It is really astonishing how contaminated the air of
racking rooms, tun-houses, etc., may become by neglect of
thorough cleanliness, and good ventilation. For example :
our attention was on one occasion called to the state of a
water-tank used for purposes of general supply in a tun-
house or cleansing room. The water in this tank smelt
badly although it emanated from a good source, and was
not unfrequently renewed. On examination, a black sludge
was found at the bottom, consisting of bacteria and yeast
cells, most of the latter being stained black by contact
with iron. The whole mass of sludge was developing
sulphuretted hydrogen freely. The yeast and bacteria had
doubtless mainly come from the air of the place, and had
fallen into the tank, whose only covering consisted of a
few loose boards.
It is of no little importance that the drains of a brewery
should be in good working order and effectively " trapped."
Brewery Vessels, etc., etc. 161
Pipes for waste liquids from upper floors should, where
convenient, discharge into properly constructed open
gratings on the ground level, thus helping to avoid direct
communication with the sewer ; for sewer-gas is bad
anywhere and must, if discharged into the brewery, help to
convey organisms that have their proper place elsewhere.
A point Worth noting in connection with the con-
tamination of beers by foreign organisms is, that whilst
the present method of "dry hopping" is pursued, it would
be almost absurd to rigidly exclude bacteria, etc., during
the manufacture of the beer, and subsequently introduce
them with dry hops, by myriads, to the finished article :
at the same time, all reasonable precautions are worthy
of observance, to ensure freedom from excessive aerial
The most scrupulous cleanliness is, in our opinion, called
for in the case of the surfaces of vessels more especially
the wooden ones with which the worts and beer are in
actual contact. In the first place, moist wooden surfaces
seem to provide a not unsuitable habitat for bacteria
and moulds,, which may not only retain their vitality
for a long time in the pores of the wood, but even
multiply there ; and thus a liquid contained in the vessels
may, by its movements, detach and carry away active
organisms from the surfaces under consideration. We
have frequently had cause to examine shavings and portions
of wood taken from old fermenting vessels, unions, union
troughs, and tunning casks. By breaking these pieces up ;
soaking in water ; pouring off the latter, and examining the
sediment formed on standing a little while ; a motley array
of organisms is frequently exhibited, amongst which we
have seen the following :
1 62 Brewery Vessels, etc., etc.
Ordinary rod and thread bacteria, probably B. lactis
and Bac. subtilis.
Moulds growing in the torula form.
Mould hyphse and spores.
Even with the greatest care, wooden vessels must of
course deteriorate in time by wear and tear, and when the
wood becomes spongy it is almost impossible to secure
cleanliness. Decay is greatly hastened, however, by
imperfect cleansing ; for then bacteria, etc., have a better
chance of disintegrating the woody tissue. The rational
course to pursue, is regular and thorough cleansing ; replac-
ing the vessels when really old, by new ones.
The foregoing remarks on brewery utensils apply quite
as strongly to cask plant, of which we have already spoken
in connection with moulds.
It is almost beyond question that of all disinfectants
bisulphite of lime and sulphurous acid but preferably the
former are the most effective and convenient for use in
connection with the cleansing of wooden vessels, for they
have a powerful action on both moulds and bacteria,
more especially perhaps on the latter.
The metal vessels of a brewery are, with the exception
of pipes, pretty easily cleansed ; but pipes require special
attention and methods. It often happens that a gelatinous
or leathery film is formed in pipes used for the convey-
ance of worts, etc., which film is not adequately removed
by brushing, and indeed can only be detached and cleared
away by strong, hot, caustic alkali. Such films generally
contain bacteria in swarms, besides other organisms.
1 6 3
GENERAL REMARKS ON THE BREWING PROCESS.
A LTHOUGH we shall presently be travelling beyond
/X the scope of the immediate application of the
Microscope to the Brewing process, we do not think it
will be altogether out of place if we offer some remarks
on certain side issues that appear to us from their general
interest to call for notice. We think it worth while at
the same time to recapitulate some points already treated
As we have already shown in Chap. IV., all store
yeasts may be regarded as mixtures, in which one type
or species of Saccharomyces predominates according to the
nature of the process ; and where the results of this last
are the most satisfactory, there is doubtless a greater
persistency, and consequently a larger proportion of the
ferment best adapted to the method of brewing pursued :
in other words, the yeast is in unison with the character
of the materials and process.
With a method unsuited to the persistence of a desirable
species of yeast, there must be deterioration of the latter ;
and the same state of things is arrived at, if a fresh
pitching yeast be employed that is unsuitable to the process
pursued; as for example, trying to carry out a " Stone
1 64 General Remarks on the Brewing Process.
square" fermentation with Burton yeast, or pitching
Burton worts with London yeast, and attempting to work
them on the Burton system.
Deterioration of the store-yeast may be discovered by
the change of character or inferiority of the ales produced,
before it is apparent by the microscopical examination of
the yeast itself. When traceable by the latter means, it
may exhibit itself as follows: (i) By the alteration in
appearance of the cells of S. Cerevisiae. (2) By the
incursion of bacteria. (3) By tEe presence of wild yeast.
The two former conditions are more easily distinguishable
than the latter, which is sometimes only to be ascertained
by fractional cultivation according to Hansen's method,
or some modification of it ; as an example : Some few
years ago, one of us in conjunction with Mr. Wall is
Evershed,* experimented on a reasonably pure-looking
sample of Burton yeast, and by a process of separation,
based on the degree of temperature at which different
species of yeast were killed, the presence in the sample
of S. Minor, S. Coagulatus No. 2, and spores of Mucor
Racemosus, was demonstrated ; besides which, some
very curious large pointed cells of yeast were obtained,
which may, however, have been only modifications of
S. Cerevisiae, induced by the high temperatures to which
the yeast was submitted to effect the differentiation.
Now this being possible with a good average Burton
yeast, it is clearly obvious that yeast from an irregular
and faulty process would contain a large proportion of
wild ferments ; and that it does so, is well-nigh a certainty
in the majority of cases. We have met with pitching
yeast that contained a large quantity of S. Pastorianus,
and ascertained that the beers of the Brewery in which this
particular yeast was produced, were liable to S. Pastorianus
frets of a marked kind. Considering the variety of alcoholic
* "Brewer's Guardian," vol. xiv., page 181.
General Remarks on the Brewing Process. 165
ferments existing in nature, it is not surprising that store-
yeasts are liable under suitable conditions, to become mix-
tures of them. Spontaneous fermentations of saccharine
liquids exposed to air are nearly always carried out by a
variety of ferments, though possibly one or more forms
may preponderate according to the nature of the liquid ; for
example, S. Apiculatus often appears and grows readily
in the expressed juice of the grape, but grows only with
difficulty in beer-wort even when freely sown therein. A
natural selection has doubtless taken place in the case of
brewers' yeast which, from a general point of view, may be
regarded as an educated or modified form from spontaneous
or air-sown fermentation in the distant past ; all normal
yeasts containing a predominating quantity of this naturally
selected form. We may remark in dealing with this
subject, that if fermentation of beer- wort be inaugurated
by means of barley-dust, a moderately pure and regular
growth of yeast is generally obtained, which when separated
from extraneous matters, dirt, etc., is indistinguishable from
some ordinary pitching yeasts. It seems to us probable
therefore, that S. Cerevisise is one of the ferment forms to
be found on barley ; our experiments, although incomplete,
point at least to this.
We have distinctly to insist upon the fact that brewery
yeasts that appear pure and homogeneous may, and gene-
rally do, contain different species of Saccharomycetes of
different degrees of persistency, according to the nature
of the process. These species are often almost identical
in appearance, and in one or two cases not very dissimilar
in their fermentative action, and it is not until an abnormal
percentage of one or other species appears that the presence
of these foreign organisms is easily demonstrable ; though
some time before this, the yeast may exhibit peculiarities
and irregularities in its mode of action.
We have already alluded to the question of a possible
1 66 General Remarks on the Brewing Process.
introduction into this country of pure yeast cultivation, and
some points that arise in connection therewith. Whatever
may be done in this direction, a considerable time must
elapse before even the preliminaries of a practical issue are
decided : in the meantime, the aim of every brewer should
obviously be to study the conditions best suited to the
production of a required type of yeast, and thus secure its
continued reproduction in a state of relative purity. That
this can be done, hardly admits of a doubt, for there are
breweries in the United Kingdom producing an almost
unvarying type of yeast, rendering any resort to outside
" changes" practically unnecessary.
To treat of all the known or speculative causes of yeast
deterioration would be going far beyond the province of
this work ; at the same time it will occupy but little space
to summarize the main causes, and the foregoing chapters
will perhaps have indicated how far the Microscope is able
to assist in identifying them. We may classify the causes
as follows :
i. Those connected with materials : Water, Malt,
Hops, Sugar, etc.
2. Those in connection with the process: Temperatures
employed. Periods of duration of certain opera-
tions. State of vessels, etc.
3. The condition of the pitching yeast at any given
time ; dependent mainly on the first two sets of
The well-known causes of mishap to the brewer stated
above in general terms, are :
Impure steep water.
Indifferent or bad barley.
Contaminated brewing water.
Unsuitable mashing temperatures.
General Remarks on the Brewing Process. 167
Unsuitable fermenting temperatures, and inadequate
control of the fermentations.
Markedly impure pitching yeast.
A few remarks on some points arising from the above.
We have already taken cognizance of the fact that
organisms bacteria, moulds, etc. occur on the surface
of barley, and have also alluded to their presence in
numbers in ordinary steep-water ; so that it will be
readily understood, that an impure steep-water may not
only bring these organisms much more quickly into
active vitality, but may also furnish a supply of its
own : a free growth of mould on the "floors" would be
a very natural sequence, especially in mild or warm
weather. In the case of impure brewing-waters, any
contained organisms would in all probability be killed
during the heating up for mashing : any deteriorating
influence resulting from the constitution of the water
being, of course, a purely chemical question.
In connection with fermentation, certain abnormal results
are obtained from time to time, that seem to be traceable
to "materials," rather than to the yeast itself. We may
mention, more especially, "boiling'' or "bladdery" fer-
mentations, and " stenchy " fermentations. We have
carefully examined yeast accompanying cases of this kind,
without detecting anything distinctly unusual in its appear-
ance. One or two cases of "bladdery" fermentation
we have traced with certainty to slack malt, and one
case of " stenchy " fermentation to sulphured hops ; but
it is almost certain that other and more obscure influ-
ences may tend to produce " stench," this being caused
by some modification of the fermentative action of
the yeast not traceable by the microscope. It is hardly
necessary to say that a "bladdery" fermentation does not
produce a good crop of yeast, either as regards quality or
1 68 General Remarks on the Brewing Process.
One of the chief conditions regulating the production of
a yeast of uniform type is a reasonable uniformity in the
character of the worts, and the mode of fermentation.
The yeast must by careful selection, be kept in a
certain state of equilibrium as regards chemical con-
stituents ; it must neither be impoverished by want
of adequate nutrient matter, nor repleted by excess
of the same, for instance : if a quick yeast like that of
Burton be carried through consecutive worts of high
gravity, a marked deterioration in fermentative vigour
ensues, owing doubtless, to a repleted state of the ferment,
which has become so rich in protoplasmic contents that
saccharine solutions no longer exert their normal stimulating
effect ; and it is quite possible that in addition, the cells are
alcoholized or partially asphyxiated. Yeast thus deteriorated
may be restored to activity by fermenting in a compara-
tively weak wort, and it therefore seems a fair argument that
the surplus cell-constituents go to form new cells, without
drawing so much on the cell-forming constituents of the
wort. In contradistinction to the above, it not unfrequently
happens that yeast becomes impoverished by consecutive
growth in weak or average-gravity worts from a poor class
of material, as also from the excessive use of sugar ; in
the latter case an occasional all-malt brewing helps to
restore the vigour of the yeast : in the former case, the
same may be effected by putting the yeast through
stronger worts, or worts from a better class of malt.
One of the most important influences on the well-being
of yeast and its degree of activity, is that exercised by
aeration or oxygenation. Yeast from quick fermentations
will bear with advantage a very thorough exposure to air
before being set in succeeding fermentations, and there can
be no doubt that the worts should have a short but complete
exposure to the air during cooling. These conditions are
certainly found in the Burton system. With medium and
General Remarks on the Brewing Process. 169
slow fermentations caused by corresponding ferments, initial
aeration does not seem to be quite so important ; the
fermenting liquids, especially in the cases of the Scotch
and Yorkshire Stone-square systems, receiving supplies of
oxygen in detail by rousing in the first case, and rousing
and pumping in the second ; the action of the yeast being
also modified by low pitching heats and attemperation.
The yeasts produced by essentially different methods
have an undoubted tendency to retain their particular habit,
and consequently it is practically impossible to transform a
fast yeast into a slow one, or vice versa, in one operation.
We may now consider briefly the chief effects produced
by yeast deterioration in beer itself, that is to say, effects
more directly connected with the actual state of the pitching
yeast. We have
Imperfect attenuation and cleansing.
Faulty behaviour in cask, e.g., flatness, fret, persistent
cloudiness, followed possibly by bacterial deteriora-
tion and finally, acidity.
The causes of many of these changes are well summed
up in Pasteur's proposition ; "that every unhealthy change
in the quality of beer coincides with the development
of microscopic organisms which are alien to the pure
ferment of beer." We have already described in some
detail in previous chapters, the alcoholic ferments and
bacteria associated with many of the changes for the worse,
that beer undergoes ; in all such cases of change the
microscope may be well applied as a first aid : at the same
time it is evident that a final solution of the question must
generally be sought in the chemistry and physics of the
process, the microscope being, nevertheless, a valuable
adjunct as a means of investigation.
MICRO-PHOTOGRAPHY, also and perhaps more
correctly termed Photo-micrography, is for those
who have the inclination and leisure, not only a most
interesting pursuit, but a far readier means of obtaining
durable records of microscopic objects than can be secured
The following apparatus is desirable : a |-plate Camera,
without a lens, or from which the lens can be readily
detached, and the usual photographic accessories, including
Dry-plates, Chemicals, Dark room, etc., or instead of this
latter, the developing may be performed at night in a dark
apartment, using a ruby lamp as source of light.
It is more convenient for the Camera to be placed
vertically over the Microscope, and for this purpose two
forms of stand are to be recommended. The first, which
we ourselves use [Plate XXL], has two upright iron rods
carrying a movable wooden platform covered with cloth,
having a circular hole about two inches in diameter in the
centre, and side ledges which allow the camera to pass
between, with little brass buckles to secure it firmly in
position. A small distance is preserved between the
camera face and platform by an inch-wide strip of thin
cardboard or vulcanite close against each ledge ; this raises
the Camera a trifle, and allows a thin sheet of vulcanite
about three inches wide to be moved backwards and
forwards freely between the Camera and platform. This
FROM A PHOTOGRAPH
BMflOS & SONS. LIT'.
Appendix A. 171
movable piece acts as a shutter, regulating the admission
of light from the microscope tube to the ground-glass of
The microscope, as will be seen by reference to the
Plate, stands vertically under the platform, the end of the
tube being enclosed in a black-velvet cylindrical bag, which
at the upper end is fastened light-tight to the under side
of the platform, and around its central opening. This bag
allows various distances between the microscope tube and
the platform, but does not interfere with the passage of
The other form of stand, which is simpler than ours, but
must be strongly and firmly made to prevent shake, is
virtually a large retort-stand. It consists of a platform
having a strong metal rod fastened to it ; on this rod an arm
can be adjusted at various heights by a clamping screw.
The velvet bag may be used as before, and some arrange-
ment is desirable for quickly fastening and unfastening the
Both these stands allow the observer to handle the
adjustments of the microscope conveniently, and to look
straight down on the image formed on the ground-glass
screen of the Camera.
Moderate sunlight or fairly strong artificial light is
adequate for magnification up to about 200 diams., but
from 250 and upwards, a very powerful paraffin or
incandescent gas burner is at least necessary. Direct
sunlight sometimes serves, but is as a rule very destructive
of definition. An Oxy-hydrogen or Oxy-coal-gas lantern,
though an expensive luxury, seems to be the most satis-
factory source of illumination for high powers. A useful
form of paraffin lamp was described in the November
number of the " Society of Chemical Industry" for 1888 ;
it is said to give very good results, and would we think,
certainly do so with moderate magnifications.
172 Appendix B.
The Microscope can be used with or without the
eyepiece, according to the size of the disc obtained on
the screen of the Camera, and the definition accom-
panying either condition. The actual magnification can
be determined, as in Chapter II., for any distance of
Camera-screen from the top of the microscope tube, by
photographing an ordinary micrometer scale, and com-
paring the value of the micrometer divisions with the lines
depicted on the negative.
Space does not allow us to enter into details of ordinary
photographic manipulation, they may well be gathered from
a good handbook on photography, and better still by a
practical exposition from some experienced photographer ;
for to see the operations skilfully performed is better than
any amount of reading.
ON PREPARING AND MOUNTING OBJECTS FOR THE
The objects encountered in the Brewing Process,
permanent specimens of which may be desired, are :
Sections and dissected portions of the Barley-corn, Alco-
holic ferments, Moulds, and Bacteria : any other objects
being probably amenable to the treatment necessary for
the forms mentioned.
If it be required to keep water-mounted objects such as
yeast, etc. for some hours, and it is a case where glycerine
is not advisable, we have found it a good plan to brush a
little cedar-oil round the edge of the cover-glass, so as to
seal in the water. Specimens may be preserved for some
Appendix B. 173
days and even weeks by this method. The oil can
subsequently be easily removed with a little turpentine.
Sections of the Barley-corn are best made by embedding
corns in the desired position in melted wax or paraffin-wax
contained in an instrument called a Microtome, and then
taking off shavings with a keen razor dipped in cold
methylated spirit. The sections may be detached carefully
from the surrounding wax, any remaining wax being
dissolved away by immersing them in turpentine.
They may be mounted in Canada Balsam, but in this
case the definition is not good. Glycerine is a better
medium, but it is very difficult to find a cement for the
cover-glass edges. Gum dammar seems to stand fairly
well. With Canada balsam the ordinary method of
mounting would be as follows : a scrupulously clean
cover-glass and slide are taken, and on the latter a drop of
Canada balsam is placed, which is judged sufficient to just
extend to the margin of the cover-glass when this last is
pressed down on it. The slide is gently warmed, and any
air-bubbles are skimmed off the Balsam with a heated
needle mounted in a wooden handle ; the section is taken
out of the turpentine, the excess of the latter being removed
by clean blotting paper, and is then introduced into the
Balsam drop, any fresh air-bubbles being removed as
The cover-glass being warmed is now carefully put on,
pressed down, and held by a small spring clip for some
hours, until the Balsam has set. Any excess of Balsam
may be removed by careful scraping, and after the
lapse of a day or two, by careful cleaning round the edges
of the cover-glass with an old silk-handkerchief dipped in
In the case of glycerine mounting, the wax is mechanically
removed from the sections, which are carefully immersed
in a drop of slightly warmed glycerine ; air-bubbles being
174 Appendix B.
skimmed off, a cover-glass is pressed on, excess of glycerine
wiped away, and the sealing medium applied with a brush
on a Shadbolt turn-table. We have not tried it ourselves,
but think it likely that sections might be preserved in a
raised cell, or a glass cavity-cell, in a solution such as
Goadby's (see Appendix C. III.), and finally sealed off on
the turn-table with water-tight cement.
So far as we know there is no really satisfactory way of
mounting yeast. Glycerine alters the appearance very
markedly. Goadby's solution might answer, but would
probably give opacity. A solid transparent medium yielded
by a strong solution of white gelatine would enable
specimens to be kept for a time. Possibly, drying off
gradually in a drop of levulose solution might also serve.
Bacteria, after staining by some such method as that
mentioned in Chap. VII., and drying off, can be moistened
with a little turpentine or aniline oil, and a drop of Canada
balsam laid on and treated in the manner described for
mounting Barley sections. The Bacteria should previously
have been diffused in a liquid which will not leave a
residue of its own, otherwise the definition is not good.
Mould specimens, can like many others, be mounted dry
in raised glass or wax cells ; the latter are made by cutting
or punching out rings from a thin sheet of wax, paraffin-
wax, or waxed cardboard, by means of sharp " cork borers "
or punches dipped in methylated spirit : cardboard or paper
rings dipped in melted wax may also be employed. The
wax rings are dried and attached to the slide by slightly
warming it to a temperature a little short of melting point
of wax, and pressing the rings down gently with some flat
surface. The growth may now be attached to the slide by
the least touch of Canada balsam, and then the cover-glass
slightly warmed and pressed down on the wax-ring. A
protecting varnish can be laid on by means of the turn-table.
The appliances required for simple mounting are :
Appendix C. 175
Small quantities of Canada-balsam, Glycerine, Gum-
dammar, Gold-size and Asphalt-varnish, solutions of Methyl-
violet, Aniline magenta, and perhaps one or two other
aniline dyes, Slides and medium-sized Cover-glasses,
some wax and waxed-cardboard rings, a pair of small
brass forceps, two or three needles in handles, one or two
spring-clips for holding down cover-glasses, a spirit lamp or
some other source of heat, a small copper or brass plate for
drying off and warming, and a turn-table. Many of the
accessories for mounting can, with a little ingenuity, be
If further detail be desired, we should advise the student
to consult some special work on the subject : a very
useful little hand-book is " The Preparation and Mounting
of Microscopic Objects," by Thomas Davies.
VARIOUS PREPARATIONS FOR THE CULTIVATION AND
PRESERVATION OF ORGANISMS.
I. GELATINE FOR CULTIVATIONS. In making this
preparation, use preferably the transparent white thin-
First make a test solution to ascertain the consistency
resulting ; using i oz. of gelatine to about 10 oz. of water in
the following manner : Break the plates of gelatine into
small pieces, and soak for a few hours in cold water ; add
the remainder of the water hot, and digest on a sand or
water bath at about 160 F. till completely dissolved. The
liquid filtered clear through felt bags can be collected in
176 Appendix C.
flasks, test-tubes, or in whatever vessels it may be required.
The mouths of the vessels being closed with cotton wool,
the gelatine may be completely sterilized by heating in an
oven or water-bath to about 180 F. for about an hour or
so. The original gelatine solution may be mixed with
hopped or unhopped malt-wort, peptone, or other substances
according to the purpose for which it is destined.
In connection with this subject we may refer to the
"Jour. Soc. Chem. Ind.," 1885, p. 698, Percy Frankland.
Ibid, 1886, p. 114,
Ibid, 1887, p. 113, G. H. Morris.
"Brewers' Guardian," June i2th, 1886, C. G. Matthews.
Ibid, July 26th, 1887, J. G. Nasmyth.
II. NUTRIENT SOLUTIONS.
Parts by weight.
Water ... 1,500*0
Sugar Candy ... ... ... 70*0
Tartaric Acid ... ... ... 4*0
Nitrate of Ammonia ... ... 4*0
Phosphate of Ammonia ... ... 0*6
Carbonate of Potassium O'6
Carbonate of Magnesia ... ... 0*4
Sulphate of Ammonia ... ... 0*25
Sulphate of Zinc ... ... ... 0*07
Sulphate of Iron ... ... ... 0*07
Silicate of Potassium ... ... 0*07
150 cc. of a 10 % solution of pure Sugar Candy,
0*5 gramme of Yeast Ash obtained in a cupel furnace,
0*2 grm. of Ammonio-dextro-tartrate, and 0*2 grm. of
Appendix C. 177
Pasteur's fluid, with Yeast Ash replaced by Chemicals.*
Water ... ... ... ... 8,576 parts.
Cane Sugar ... ... ... 1,500 ,,
Ammonium Tartrate ... ... 100 ,,
Potassium Phosphate ... ... 2 ,,
Calcium Phosphate ... ... 2 ,,
Magnesium Sulphate ... ... 2 ,,
As Ammonium Salts rather inadequately replace Organic
Nitrogen, the Ammonium Tartrate may well be replaced
by a smaller quantity of Pepsin.
III. PRESERVATIVE SOLUTIONS FOR VEGETABLE TISSUES.
Glycerine and Gum.
Pure Gum Arabic ... ... i oz.
Glycerine ... ... i ,,
Distilled water ... ... ... i ,,
Arsenious acid ... ... ... ingrains.
Dissolve the Arsenious acid in the cold water, then the
gum, finally add the Glycerine, and mix without bubbles.
Rock Salt i oz.
Alum ... ... ^ ,,
Corrosive sublimate ... ... i grain.
Dissolve in i pint of boiling water and filter. We found
this last to answer well for keeping some specimens of
IV. CEMENT FOR RING-CELLS OR FINISHING.
India rubber ... \ drachm.
Asphaltum ... 4 oz.
Mineral Naphtha ... ... 10 ,,
Dissolve the India-rubber in the naphtha, then add the
asphaltum. If necessary, heat must be employed, but only
with great precaution.
* " Elementary Biology." Huxley and Martin, 1875.
178 Appendix D.
REAGENTS OR TESTING LIQUIDS.
(For Starch granules, Bacteria, etc.)
To \ oz. of water and J oz. of alcohol add a few crystals
of Potassic Iodide and a few grains of Iodine. A portion
of this solution may be diluted with water, till the colour is
that of a full golden sherry.
(For staining yeast or Bacteria.)
Dissolve a small piece of violet copying-pencil lead, or
the dye itself which may be easily procured in distilled
water ; dilute till quite transparent.
Solutions of Bismark brown, Eosene, Aniline magenta,
and Picric acid are all easily made, if required. Where
the substance is not readily soluble in water, a little
alcohol may be added as well.
(For clearing away resin.)
A few drops of strong Ammonia per i oz. water. A
very weak Caustic Soda or Caustic Potash solution may be
employed for the same purpose : the Ammonia solution,
however, keeps better.
Appendix E. 179
THE STORAGE OF PITCHING YEAST
Seems to us a matter well deserving of notice. Cool
vessels such as slate in a clean, cool, dust-free position,
are desirable at all times, but more especially so in summer
and autumn, when, as we know, there is the greatest risk
of aerial contamination. Attemperators are a useful adjunct
to yeast storage vessels, if a low temperature cannot
otherwise be secured.
Where yeast has deteriorated to such an extent that
some cleansing operation is necessary before it is used for
pitching, it is obvious that an immediate change is the
most desirable thing ; still a brewer may be so situated
that he is obliged to go on with his own yeast, and in
such a case the following observations may prove of
some service :
In the first place, when yeast is left to itself and is
slightly " on the work," there is a tendency for the bacteria
to come to the surface, owing possibly to their affinity for
oxygen ; consequently, if a vessel of store yeast that has
been standing some time is skimmed, a proportion of the
disease organisms may be removed. A further purification
may be effected by mixing the yeast with about ten times
its volume of cold water in a somewhat shallow vessel.
After standing an hour or two, amorphous matter and dead
cells are deposited, the remaining yeast and water being run
off from this layer. A further settling of 6 to 8 hours in a
cold place once more running off the liquid provides a
moderately clean yeast, which may be re-invigorated for
use by mixing with a little sweet wort of about 1030 Sp.
Gr. at a low temperature, some hours before pitching.
Where yeast is very impure, Salicylic acid dissolved in
a little Carbonate of Soda or Borax solution, may be
180 Appendix F.
employed with advantage in the proportion of about i oz.
per Barrel of wash water.
FOREIGN PRESSED YEAST
Varies so markedly in its appearance under the Microscope,
that only the most general description can be given. The
cells are of varying size and shape, generally well vacuoled
and nucleated, with sometimes a considerable tendency to
elliptic forms. The impurities are usually, Bacteria (often
B. lactis) and admixed starch, generally of Potato. The
power of pressed yeast as a panification ferment can only
be determined by actual experiment, being a function
connected with the temperatures at which the yeast has
been grown, and more especially connected with the
particular species of Saccharomycetes, some species being
naturally good panification ferments, whilst it is only with
difficulty that the power can be developed in others.
We may here remark that samples of pressed yeast,
wrapped in sterilized blotting paper, may be kept for a
considerable length of time in a state of comparative purity.
Hansen uses alcohol and a TO % solution of Cane Sugar
for preserving yeast.
Samples of yeast may be kept for many months or even
years, by careful air-drying and intimate admixture with
plaster of Paris ; or by a suitable mixture of whole meal
and wheat or potato starch with the liquid yeast, prior to
pressing and air-drying. In each case the success of the
operation depends upon the dried samples being kept
absolutely free from moisture, it is therefore advisable to
cover the corks of the bottles in which they are kept
EXPLANATION OF SCIENTIFIC AND TECHNICAL TERMS.
NOTE. Syn. = Synonymous ivith.
ABERRATION, an unequal deviation of the rays of light.
,, CHROMATIC, a fault in lenses which causes them to split up
white light into its component colours, giving images with
,, SPHERICAL, a fault in lenses and mirrors which causes them
to concentrate light to more than one focus, giving images
with indistinct or blurred outlines.
ACARUS SACCHARI, a small animal allied to the cheesemite, found in
common raw sugars.
ACHROMATIC, applied to a lens free from chromatic aberration.
ACROSPIRE, the bud of a germinating barley-corn. Syn. Plumule.
AEROBIAN, term applied to ferment forms induced by growth with free
access of air.
AECIDIUM BERBERIS, a mould occurring on the Berberry plant, derived
from Puccinia graminis or "rust" of corn.
ALBUMEN, botanically speaking, the contents of the barley-corn and other
seeds. Applied by chemists to white of egg, and allied
substances found in many living bodies.
ALEURONE, a peculiar layer of cells surrounding and partly constituting the
mealy portion of the barley-corn and other seeds.
ALTERNATION OF GENERATION, the occurrence at definite intervals of a
distinctly different form of growth in the consecutive genera-
tions of living things, e.g., moulds.
1 82 Glossary.
AMPLIFICATION, the enlargement of a magnified image.
ANTISEPTIC, a substance that prevents or delays putrefaction.
APLANATIC, applied to a lens free from spherical aberration.
ARTHROBOTRYS, a mould having a clustered appearance.
ASCOSPORES, spores formed in a sac-like cell called an ascus.
Ascus, a cell or sac in which spores are formed.
ASPERGILLUS, a group of moulds, the spores of which are readily
ASPERGILLUS FUMIGATUS, a mould having a smoky appearance.
,, GLAUCUS, a mould having a bluish green appearance.
,, NIGER, a black mould.
AWN, the beard or spike of a barley-corn.
BACILLUS, a name given to short rod forms of Bacteria.
BACILLUS AMYLOBACTER, the starch-producing bacterium. Syn. Clostridium
LEPTOTHRIX, a long, thin, hair-like bacterium.
RUBER, a bacterium having a red appearance in cultivations.
SUBTILIS, a thin rod-bacterium. Syn. the hay bacillus.
ULNA, a thick jointed rod-bacterium.
BACTERIUM-A, a general term applied to the Schizomycetes or fission-
BACTERIACE^E, term applied by Zopf in his classification of the Bacteria, to
a group including a variety of forms, and amongst them short
BACTERIUM ACETI, a bacterium producing acetic acid.
,, BUTYRICUM, a bacterium producing butyric acid. Syn. Bacillus
amylobacter; Clostridium butyricum.
,, FUSIFORME, a bacterium having a spindle shape.
PYRIFORME, a bacterium having a pear shape.
XYLINUM, a bacterium producing cellulose.
BEGGIATOA, a microscopic organism found in certain waters.
BRACT and BRACTLET, a small leaf more or less changed in form, from
which a flower or flowers proceed.
CAMERA LUCIDA, a light-reflecting apparatus, applied to the microscope
for drawing objects.
Glossary. 1 83
CAPSULES, in botany applied to a seed-case, sometimes applied to the
resin glands or lupulin of the Hop.
CARBOHYDRATE, a chemical term for substances such as Sugar, Starch, etc.,
which contain Carbon, and Oxygen and Hydrogen in the
proportions in which they exist in water.
CASEOUS, a term applied to certain yeasts which have a tendency to fall
from a liquid as a curdy precipitate.
CATKIN, in botany, a form of flower like that of the willow and hop. Syn.
CELLULOSE, a carbohydrate forming the main constituent of all vegetable
cells. Pith is nearly pure cellulose.
CHALARA MYCODERMA, a mould forming a loose white or grey film on
CHLOROPHYLL, the green colouring matter of plants.
CHROMATIC ABERRATION, See Aberration.
CHROMOGENOUS, applied to the bacteria having the power of producing
CILIUM-A, minute hair-like filaments which act as the motile organs of
CLADOSPORIUM HERBARUM, a mould found on plants.
CLADOTHRIX DICHOTOMA, a thread-like bacterium, exhibiting the pecu-
liarity known as false-branching.
CLADOTRICHE.E, term applied by Zopf in his classification of bacteria, to
the forms exhibiting false-branching.
CLEANSING CASKS, technical term for vessels in which beer is cleansed of
CLOSTRIDIUM BUTYRICUM, a short thread bacterium. Syn. Bacterium
butyricum ; Bacillus amylobacter.
COCCACE.E, term applied by Zopf in his classification of the bacteria, to the
forms which chiefly appear as small rounded cells, cocci or
Coccus (a berry), term applied to the small rounded form of many
CONCAVE (hollowed), applied to lenses arid mirrors having a hollowed
CONDENSER, an apparatus for concentrating light on an object under
BULL'S-EYE, formed of a glass like that in a bull's-eye lantern.
CONDITION, term applied to the yellow resin-glands of the hop ; also to
beers in a state fit for consumption.
CONIFERS, an order of plants, like the fir and pine, which bear their seeds
1 84 Glossary.
CONVEX, a term applied to curved lenses and mirrors, the curve falling
away or downwards from the centre.
COOLER, technical term for a flat shallow vessel in which beer-wort is
CRENOTHRIX KUHNIANA, a bacterium occurring in wells and drain-pipes.
CRYPTOGAMIA, one of the two great divisions of the vegetable kingdom,
consisting of the flowerless plants.
CULTIVATION, the growth of any .particular organism which has been sown
in a prepared medium.
DEMATIUM PULLULANS, a mould frequently occurring in ripe fruit.
DENDROCHIUM, a white arborescent mould.
DESMID, a microscopic organism found in water.
DESMOBACTERIA, term applied by Cohn in his classification of the bacteria,
to the thread-like forms.
DIASTASE, a soluble ferment produced in germinating seeds, which is
capable of converting starch into sugar and gum.
DIASTATIC, the property of diastase.
DIATOM, a microscopic fresh-water Alga (seaweed), having a cell wall or
" valve" formed largely of Silica (sand), with regular geometric
DIPLOCOCCUS, two rounded bacteria more or less closely joined together.
DORSAL, applied to the outward side of a seed in situ.
ENDOSPERM, the internal matter of seeds such as the barley-corn upon
which the young plant feeds during its early growth.
ENDOSPORE, a spore formed in an ascus or in the body of a ferment cell.
EPICARP, term applied to the outer layer of the pericarp or seed case.
EPITHELIUM, the fine membranous lining of the internal organs of all
ERYSIPHE TUCKERI, a mould on cereals and vines. Syn. Oidium Vini.
EUROTIUM ASPERGILLUS GLAUCUS, an alternation form of Asp. Glaucus.
ORYZ^E, a mould, the spores of which are found in Koji, the
FIELD, term applied by microscopists to that part of the slide under
observation, seen at any given time through the instrument.
FLAGELLUM, a whip-like appendage possessed by many microscopic
organisms, enabling them to move freely in liquids. Syn.
Focus, the point to which rays of light or heat are concentrated by a lens
FORCING TRAY, apparatus used for keeping vessels at a constant degree of
FORCING FLASK, a glass vessel for testing beer or other liquids on the
FUNGUS, a class of non-flowering, leafless plants (Thallophytes).
FUSARIUM HORDEI, the red mould of barley, having spindle-shaped or
GLANDS, applied, in botany, to special cells containing particular substances,
such as oil, resin, etc.
H^MATIMETER, a glass slide, so ruled and fitted, that microscopic objects
placed on it may be measured or counted ; originally used for
counting blood corpuscles.
HYPHA, the tube-like, stem-forming cells of moulds or fungi, often forming
a web or net-work.
INFUSORIUM-A, microscopic organisms found in water and other liquids.
KOJJ, macerated rice containing fungus spores, used by the Japanese as a
ferment in making Sake, and bread ; also in the manufacture
LAGER, term applied to store beer brewed on the " low'' or bottom " fer-
LEPTOTRICHE^E, term used by Zopf, in his classification of Bacteria, to the
long thread and spiral forms.
LEUCONOSTOC MESENTERIODES, a bacterium which occurs in white
gelatinous masses in the expressed juice of beet- root.
LODICULE, a dried-up part of the flower of grasses, etc., which remains
attached to the seed or grain.
LUPULIN, term applied to the resin-glands of the hop flower.
1 86 Glossary.
METRE, the standard of length of the French metric system : approximately
MESOCARP, the middle layer of the Pericarp or seed-case.
MICROBACTERIA, term used by Cohn, in his classification of Bacteria,
for oblong cells which at times occur in gelatinous groups.
MICROBE, general term for microscopic organisms of the nature of bacteria.
MICROMETER, an instrument applied to the microscope for measuring
small objects or spaces.
MICRON, term now used to express the thousandth of a millimetre.
Syn. Micromillimetre of Botanists and Biologists.
MICROTOME, an instrument used for cutting extremely fine slices of objects
for examination under the microscope.
MILLIMETRE, the thousandth part of a metre.
MOLECULAR, belonging to, or consisting of the groups of atoms, of which
all substances are believed to consist.
MONAD, a microscopic animalcule found in water.
MONILIA CANDIDA, a white film-forming mould.
MONOCULAR, a microscope having one tube and eyepiece.
MUCEDINES, term applied to the moulds generally, but more correctly to a
small division of them.
MUCORINI, term applied by Nageli to the moulds ; by De Bary to one
group of them only.
MUCOR MUCEDO, a mould of very common occurrence.
,, RACEMOSUS, a mould very similar to M. Mucedo, forming a
clustering mycelium in liquids.
STOLONIFER, a mould bearing black sporangia ; the hyphae tend to
re-enter the nutrient stratum.
MYCELIUM, that part of a fungus or mould formed usually of interlaced
hyphae which corresponds with the root of other plants.
MYCODERMA ACETI, a film or " mother" forming organism.
,, VINI, an aerobian ferment ; forms what is usually called
" mother " of wine and beer.
MYCOPROTEIN, an albuminous or nitrogenous substance forming an
essential part of living cells, more especially of fungi.
NUCLEUS, term applied to granules found in the vacuoles of the yeast cell ;
and to somewhat similar granules, in living cells generally,
which originate new cells.
OIDIUM LACTIS, a mould occurring on stale milk.
,, LUPULI, a mould occurring on spent hops.
,, VINI, a mould found on the vine, and not unfrequently appearing
in wine. Syn. Erysiphe Tuckeri.
OVARY, that part of a flower in which the seeds are formed.
PALEA-JE, small leaf-like bodies attached to many flowers ; in the case of
barley, forming the outer coating of the corn : they form the
" chaff" of other' cereals.
PAPPUS, the downy hairs at the summit of the ovary in certain plants,
PASTEURIZED, sterilized by heat as recommended by Pasteur.
PATHOGENIC, that which causes disease ; applied to the bacteria associated
with certain definite diseases.
PEDIOCOCCUS ACIDI LACTICI, a small bacterium which produces lactic acid.
,, ALBUS, a small bacterium giving white cultivations.
,, CEREVISI^E, a small bacterium.
PELLICLE, a thin film ; term applied by Hansen to the surface growth of
PENICILLIUM GLAUCUM, a mould of a bluish-green colour.
CLADOSPORIOIDES, a mould occurring on the shoots of plants.
PERICARP, that part of a fruit covering the seeds ; one of the thin coatings
of the barley-corn.
PERITHECIUM, a flask or cup-shaped receptacle, containing the spore-sacs
or asci of a mould or fungus.
PITCHING YEAST, technical term for yeast used for starting a fermentation.
PLANE, a perfectly level surface, which may be at any inclination.
PLASMA, material giving rise to living matter.
PLEOMORPHY, existence of an organism in more than one form.
PLUMULE, or stem-bud, that part of the germ of a seed which ultimately
becomes the stem of the young plant. Syn. Acrospire
POLLEN, the fertilizing powder on the stamens or male organs of flowers.
POLYMORPHISM, the existence of an organism in many forms. Syn.
Alternation of generation.
PROTEID, similar in composition to protein.
PROTEIN, a substance containing Nitrogen and various other constituents
found in living things.
PROTOCOCCUS, a single-celled fresh-water alga (seaweed) : the green dust on
tree stems, old wood, etc., and the green slime in water.
1 88 Glossary.
PROTOPLASM, an albuminous or nitrogenous substance forming an essential
part of all living cells.
PSEUDOSPORES, false spores.
PUCCINIA GRAMINIS, a mould found on wheat and other cereals. Syn.
" rust " of wheat.
RAY, a single line of light or heat.
REAGENT, chemical term for any liquid or solid substance used to detect
the presence of other substances.
REFLECTION, the turning back of a ray of light or heat from a polished or
REFRACTION, the bending of a ray of light on passing into a medium of
ROUND, technical term for a vessel in which fermentation takes place.
SACCHAROMYCETES, the ferments which split up sugar and form alcohol.
SACCHAROMYCES APICULATUS, a ferment having a pointed form.
,, CEREVISLE, the usual ferment of beer.
,, COAGULATUS, a ferment having a curdy appearance when
suspended in liquids. Syn. Caseous yeast.
,, CONGLOMERATE, a ferment in which the cells are clubbed
together in a curious manner.
,, ELLIPSOIDEUS or ELLiPTicus, a ferment having elliptical
,, EXIGUUS, a ferment of small size.
,, MARXIANUS, a ferment described by Marx.
,, MEMBRANjEFACiENS, a ferment forming a film or mem-
,, MINOR, a ferment of a small rounded form.
,, PASTORIANUS, a ferment first described in detail by
,, GLUTINIS, a ferment giving rose-coloured slimy spots on
SAKE, a fermented liquid made in Japan.
SARCINA AURANTIACA, a small bacterium producing a golden yellow
,, CANDIDA, a small bacterium giving snow-white cultivations.
,, FLAVA, a small bacterium producing a yellow colour.
Glossary. 1 89
SARCINA GLUTINIS, a small bacterium.
,, LITORALIS, a small bacterium occurring in sea- water.
,, MAXIMA, the largest bacterium of the Sarcina family.
SCHIZOMYCETES, the Bacteria or fission-fungi.
SCUTELLUM, the membrane dividing the starchy part (endosperm) of the
barley-corn from the germ.
SEPTUM, a partition or division.
SPH^ROBACTERIA, term applied by Cohn in his classification of bacteria,
to round cells which at times occur in gelatinous groups.
SPH^EROTHECUM CASTAGNEI, a mould occurring on the hop- plant. Syn.
SPICULE, a minute slender point.
SPIRILLUM TENUE, a thin spiral bacterium found in decomposing liquids.
,, VOLUTANS, a spiral revolving bacterium found in decomposing
SPIROBACTERIA, term applied by Cohn, in his classification of bacteria, to
the spiral forms.
SPORANGIUM, a receptacle containing spores.
SPORES, the seeds of flowerless plants, and of the lowest forms of animal
SPORULATION, the act of forming spores.
SQUARES, technical term for vessels in which fermentation takes place.
STERILIZE, to render free from living organisms of any kind.
STILLIONS, technical term for vessels in which beer is cleansed of yeast.
STROBILE, a form of flower such as that of the hop. Syn. Catkin.
TESTA, the true skin of a seed.
TETRACOCCUS, a group of four cocci or minute bead-like cells.
THALLOPHYTES, a group of leafless, non-flowering plants, including algae,
fungi, and lichens.
TUNS, technical term for vessels in which beer is cleansed ; also applied to
Brewing vessels generally.
UNIONS, trade term for vessels in which beer is cleansed of yeast.
USTILAGO CARBO, a black mould, the " smut " or " brand " of corn.
SEGETUM, a black mould, the " smut" of corn ; found especially
VACUOLE, cavity in the protoplasm of most cells filled with cell sap.
VENTRAL, applied to the inward side of a seed in situ.
VESICLE, a little bladder ; any small membranous cavity in animals or
VIBRIO, a term applied to the short bacteria which have a rapid movement.
YEAST-FLASKS. Syn. forcing-flasks : a misnomer.
ZOOGLCEA, term applied to a gelatinous colony of bacteria.
ZOOSPORE, a motile spore of certain moulds.
ZYGOSPORE, a large spore produced in some moulds by a kind of sexual
Aberration, Chromatic - - - 10
,, Spherical - - 9
Abnormal fermentations - 167
Absorption of Oxygen by Bacteria - 104
Yeast - 38
,, Water by Barley-corn - 140
Acarus sacchari 151
Accessories, small, required to work
with the Microscope in a Brewery 20
Acetic Acid in Beer - - - - 118
,, produced by Bacteria - 103
Acetic ferment 117
Achromatic condenser ... 4
,, lens - - - - 10
Acidity of Malt, development of on tray 137
Acids formed by Bacteria - - - 103
Acrospire - - 144
Adjustment of Focus - - - - 20
,, Object glass - - 13
Adjustments, coarse and fine - - 2
Aecidium Berberris - - - -83
Aeration of wort
Age of Yeast ....
Air, contamination of in Brewery
,, filtration of
,, organisms in
Albuminoid matter -
Aleurone cells - ...
Alt Carlsberg Brewery
Alternation of generation -
Ammonia, for clearing resin
,, production and oxidation
by Bacteria -
Amplification - - ,
Amthor on S. Apiculatus -
Analyser - ....
Anatomy of Barley-corn -
Angular aperture of Object glasses
Aniline colours for staining
Animalcules in water
Appert's process ....
Aroma of Hops .....
Artificial illumination for Microscope -
38, 1 68
,, formation, table of -
,, of Moulds -
,, glaucus -
,, ,, eurotium form
Asphalt varnish ...
Assay flask ....
Awn of the Barley-corn
Bacillus amylobacter -
,, ruber -
,, ulna ....
,, formation of spores
,, affinity for Oxygen
,, associated with Brewing
,, Cohn's classification of -
- 8 9
- 8 9
- 8 9
- 8 9
" 6 7
disintegrating woody-tissues - 162
early observations of -
effects of antiseptics on -
,, electricity on -
,, plasma on
,, substances on -
Flugge's classification of
gelatine cultivation of -
growth arrested by products - 103
in air 109
in fossil remains - - - 108
involution forms of - - 101
modes of cultivation - - 105
,, reproduction - - 99
,, research - - 1 06
movements due to cilia - - 98
plate-cultivation of - - 106
products of decomposition - 103
pure growth of 106
relationship to alcoholic fer-
ments, and moulds - - 108
reproduction by fission - 101
research - - - - 106
retrograde forms - - - 101
spore formation - - - 102
Bacteria, spores of, not easily killed - 105
staining .... 107
structure - - - - 98
to - - - - 105, 158
variation of form - - - 99
zoogloea form - - -102
Zopfs classification of - - 100
Bacteriological examination of water 153
Bacterium aceti -
Kochii - - -
,, in beer
Baker's yeast ....
Barley, black mould of
,, blue mould of
,, red mould of
Barley-corn, absorption of water by
changes during germina
external structure -
general appearance of
germinal parts of -
internal structure -
number of rootlets -
starchy part -
Barley dust, organisms in -
Bary, De, on Sarcina
Beale's neutral tint reflector
Beer, Belgian -
forced samples -
Belgian Breweries, apiculatus in -
Bersch on Sarcina in beer -
Bisulphite of Lime as an antiseptic
,, ,, use in brewery
Black mould of Barley and Hop
Body of the Microscope
Boiling, for sterilization
Borax, use of
Botrytis cinerea - - - -
Bottled beer, sediments
Bottom yeast ....
Bract and Bractlet of Hop -
Brefeld on Alcoholic ferments
Brewers' yeast, microscopic
- 45. 47
Brewery drains - - - - 160
Brewing process - -163
,, vessels - - 156, 161
Brightness of field - - - - 13
Brown, Adrian - - - - 117, 119
,, Horace T. - - - 129, 145
,, and Morris - - - 45, 78
Brownian movement - 56
Budding of yeast - - - -34
Bull's-eye condenser 6
Burton Yeast 42
,, ,, wild forms in - - 164
Butyric acid fermentation - - 122, 151
Cagniard Latour, early researches in
fermentation - - - - 28
Camera applied to microscope - - 170
,, lucida 7
,, ,, position of microscope
when in use - - 21
Canada Balsam - - - n, 175
Capillary attraction - - 139
Capsule of Hop .... 148
Carbonic acid produced by fermentation 41
,, ,, bacterial growth 103
Carlsberg brewery - - 74, 76, 157
Caseous ferments - - - - 46
,, ,, suggested name for
41 f.n., 48
Caspary on Sarcina - - - - 113
Casks, mould on - - - - 81
,, cleanliness necessary - - 162
Catkin of Hop - - - 147
Cells, appearance of when dead - - 43
,, for mounting objects - - 174
,, for observing growths - - 68
,, power of endurance - - "33
Cell, Bottcher's - - - - 68
,, Ranvier's - 69
Cell-juice or cell-sap - - - '33
Cell-wall, appearance of 32
,, composition of - - -31
Cements for mounting - - - 177
Chalara mycoderma - - - - 86
Chamberland filter - - - - 155
,, flask - - - 66
Cheese, ripening of, due to bacteria - 97
Chemical nature of yeast - - -31
Chlorophyll - 81
Chromatic aberration - - - 10
,, ,, correction for - n
Cilia of bacteria - - - - 98
,, moulds - - - - 82
Circulation of liquids in barley-corn - 141
Cladosporium herbarum - - - 157
Cladothrix dichotoma - - - 100
Classification of bacteria - - - 98
,, forced beers - - 135
,, moulds - - 80
,, organisms met in the
brewing process - - - 26
Cleanliness of microscopic glasses - 16
,, brewers' vessels, impor-
tance of 160
Cleansing media - - - 162
Clostridium butyricum - - 122
Coagulatus, S. - - - 48
Coarse adjustment of microscope - 2
Coccacese - - 100
Cohn, classification of Bacteria - - 98
,, on B. subtilis - - - - 124
,, on B. termo - 122
Coke for filtering - - - 155
Collecting samples of beer - - - 133
Collins' diaphragm .... 4
Colour-producing bacteria - - - 102
Comparison of standards of measure-
ment - - - - - 25
Compound Microscope, mechanical
construction of - - - I
Compound Microscope, optical prin-
ciples of 9
Concave lenses 9
,, mirrors - - - - 5, 8
Condenser, achromatic ... 4
,, bull's-eye 6
Condition of hop - 147
Conglomerate, S. - - - - 77
Coniferse, bacteria in fossil - 108
Convex lenses ----- 9
Coolers, aeration by - - - 168
Correction for chromatic aberration - 10
,, spherical aberration - 10
,, thickness of cover-glass 13
Crenothrix Kuhniana - - - 101
Cultivation of bacteria - - - 105
,, ,, gelatine for - 175
,, pure growths
Dallinger, Dr., recent work of
Dammar, for mounting
Decomposition due to Bacteria
De Bary, Dr. -
D^e Seynes on Ascospores -
Defining power of object-glass
Dematium pullulans -
Desmids in water
Deteriorated yeast, effects of using
Deterioration of yeast
,, ,, causes of -
Development of yeast
Diameter of objects, method of ascer-
Diatoms in water
Diseases produced by the Schizomy-
Disinfectants in a Brewery
Dissection of Barley-corn -
Dorsal side of Barley-corn -
Drams of Brewery - - 160
Draw-tube of Microscope - - - 6
Drawing, desk for - - 22
,, objects from the microscope 23
Dry-hopping, effects of - 46, 150, 161
Dumas, experiments on fermentation - 30
Dust, atmospheric - - - 109
,, barley - - . - -149
,, hop 149
,, of breweries - - - - 62
Ehrenberg on subtilis - 124
Ellipsoideus, S., or eliipticus, S. - 45, 49
Embryo rootlets of Barley-corn - - 144
Endogenous spore formation - 36
Endosperm - - - 142
Engel on S. Minor - - - - 50
,, spore formation - - - 36
English beer, the alcoholic ferments of 40
Erysiphe Tuckeri - - - - 87
Eurotium aspergillus glaucus - - 89
,, Oryzse ... 85
Evershed, VVallis - - - - 164
Exiguus, S. 52, 77
Eye-lens ------ 2
,, ,, action of - - n
,, ,, micrometer - - - 24
,, ,, mode of designating - - 12
Ferment, definition of term - - 40
Fermentation, abnormal - - - 167
acetic- - - - 117
alcoholic - - - 40
"bladdery" - - 167
" bottom " or " low " 57
butyric - - - 122
cause of - . - 28
conditions favourable to 37
"high" or "top" - 57
lactic - - - - 120
moulds producing 85, 90
of beer - - 27
of milk - - - 97
- I5 2
of wine - - 27, 44, 49
products of - 41
spontaneous 27, 165
secondary - - - 45
stenchy - - - 167
Ferments, species identified by Hansen 70
in Brewers' yeast 41, 164
,, unorganised - - -41
Field lens 2
Film formation 72
- !5 2
table .... 74
Film of dirt in Brewery pipes - - 162
Filtration of water - - - 154
Fine adjustment of Microscope - - 2
Fission-fungi - - - - - 96
Flagella of bacteria - - - - 98
,, moulds 83
Flask, assay - - - 67
,, Chamberland ... 66
,, forcing - - - - 132
,, Pasteur - - - - 65
,, method of sterilizing in - - 133
,, vacuum ' - - - - 66
Flatness of Field of Microscope - - 13
Flavour of beer, partly due to species
of Ferment 41
Flint glass for lenses - - - - n
Floors of Brewery and Makings, clean-
ing .... . 160
Fluid, Pasteur's - - - - 176
,, Raulin's - - - - - 176
Fliigge's classification of the Bacteria - 100
Focal length - - - 9, 12
,, ,, adjustment of - - - 13
Forced-beer samples, classification of - 135
,, ,, description of 136
,, ,, examination of - 135
Forcing flasks - - 132
,, ,, cleaning of - - 133
Forcing process - - - - 128
Forcing tray, construction, etc. - - 129
heating- - 130
other uses - - - 137
period on - 134
regulator for- - - 130
samples for - - 1 33
temperature for - 134
Foreign pressed yeast - 180
Foreign yeasts - - 57, 74
Fortuitous fermentation - - -27
Fractional cultivation- 164
Frankland, Prof. E., phosphates in
waters - - - - 152
Dr. Percy, bacteriological
examination of water - 153
Fret - 39
,, ellipsoideus - - 49
,, exiguus 52
,, Pastorianus ' - - '45; 164
Fungi ...... go
Fusarium hordei - - - - 93
Gelatine, for cultures of bacteria, etc.
68, 106, 175
,, of Barley-corn - - - 141
Germinal spot on ferment cell - 34
Germs, hardiness of - - - - 105
,, in air 109
,, ,, conditions influencing - 157
Glass, flint 1 1
,, lead, in forcing flasks - 135 f.n.
Glycerine, for mounting - - - 177
,, produced in fermentations - 41
Goadby's solution - - - - 177
Grains, bacteria in - - - 97
Granules in Yeast - - - -33
Gum-dammar - 175
Hand-lens, use of - i f.n.
Hansenascospore formation - -70
,, early researches - - - 62
,, life-history of S. Apiculatus - 51
,, organisms in air of breweries,
etc. 62, no, 157
,, pellicle or " film " formation - 72
,, pure yeast culture - - - 61
>, ,, practical ap-
plication - - - -76
,, variation of ferments - - 70
Heat, effects on yeast, etc. 28, 30, 37
,, for sterilizing - - - 20, 30
Heisch's test for water - - KI
" High " fermentation
Holm & Poulson, detection of wild
Holzner & Lermer, work on barley
com - ....
black mould of -
dust, organisms in
microscopic examination of -
mildew - ...
oil, change due to age
yellow mould of -
1 1 op -sickness - ...
Huth, S. Von, on Sarcina -
Identification of yeast, historical sketch 28
Illumination of opaque objects - - 6
,, of transparent objects - 5
Immersion lenses - - 14
Infusoria in water .... 152
Inoculating sterilized liquids - - 67
Instrument makers - - - - 14
Invertin in yeast - - - - 41
Inverting of images by microscope - 18
Involution forms of bacteria - 101
Iodine solution 178
,, action on some bacteria
Joliannsen, work on barley-corn - 146
Klebs on pure cultivations, etc. - 63, 101
Koch on pure cultivations, etc. - 63, 154
Koji, preparation of - - - "85
Kutzing on Sarcina - - -113
Lactic Acid - 120
,, ,, produced by B, Subtilis - 124
,, ,, Sarcina - 113
,, ,, use of in distilleries - 120
Lactic ferment, ordinary - 120
,, of Pasteur - - 119
Lager-beer process - - - " 5&
, , recent researches in - - 57
yeast - 57
Lamp for microscope 7
,, shade ... 7
Lechartier and Bellamy, fermentation
of fruits 29
Lenses, correction of - - - - 10
,, action of 9
,, used in microscope - - 9
Leuconostoc mesenteroides - - 116
Leuwenhoek, early microscopic obser-
vations - - 28, 96
Liebig's views of fermentation - - 30
Life-history of yeast cell - - - 34
Light, arrangement for transparent ob-
jects - 5, 18
,, opaque objects 6, 1 8
,, polarized 5
,, sources of - - - 6
,, suitable for microscopic work
generally - 18
Lime, bisulphite of use in brewery - 126
Lindner, Paul, on Sarcina - no
,, ,, ,, Summary of
observations - - - - 112
Lister on pure cultivations - - 63
London yeast - - - 42
Low fermentation - - 57
Lupulin, microscopic examination of - 147
,, changes in, caused by age - 148
Magnifying power of a microscope - 24
Manipulation of microscope - - 16
Malto-dextrin, fermentation of - - 45
Malts tested on forcing tray - - 137
Maize beer 27
Marsh gas produced by bacteria- - 103
Meat-extract for bacterial growths - 106
Method of calculating number of cells 64
Methyl-violet for staining organisms - 178
Micrometer eyepiece - - 24
,, lines - - - 23
Micromillimetre - - - - 25
Micron - - - - 25 f.n.
Micro-organism - - - - 96
Microphotography, apparatus for - 170
,, light for - - 171
,, methods of - - 172
Microscope, binocular - - - 2
choice of a - - 14
magnifying power - - 24
makers - - - - 14
Microscope, powers for different ob-
jects - - - - 18
principal parts - i
qualities of a good - 14
requirements of a brewers' 7
simple - - - i f.n.
small accessories of - 7
small accessories of a
brewers' - - - 20
Microscopic fungi - - - - 80
Microtome - - - - 173
Milk, fermentation of - - 120
Minor, S. 50, 77
Miquel's experiments, organisms in
air - - 109, 156
Miquel's experiments, organisms in
Miquel's experiments, conclusions - 156
Mirrors used in the microscope - - 5
,, ,, ,, mode
of action 8
Monads in water - - 152
Monilia Candida - - - 93
Monocular microscope - - - 2
Morris, Dr. G. H. - - -71
"Mother" of Vinegar - - - 117
Moulds or microscopic fungi - - 80
,, alternation of generation - 83
,, components of - - - 84
,, cultivation of - - - 94
,, details of structure - - - 82
,, effects of antiseptics on - - 127
,, ferment form of - 85
,, general microscopic appear-
ance of - - - - 82
,, general occurrence - - - 81
growth arrested by products - 103
,, ,, in mineral solutions - 83
,, ,, on malting floors, etc. 167
,, industrial application of- - 85
,, modes of reproduction - - 82
, ,, mounting for the
microscope - - - 174
,, motile spores of - - - 82
,, position in vegetable kingdom 81
,, products of growth of - - 84
,, sporulation of - - - 82
, , variety of forms - - - 80
Mouldy malt causing faulty beer - 1 59
Mounting objects for the microscope - 172
,, ,, appliances for - 175
Mucorini 80, 101
Mucor mucedo 90
,, ,, submerged as a ferment 91
,, racemosus - - - - 89
,, ,, submerged as a ferment
Must, fermentation of
Nageli, theory of fermentation - - 30
,, ,, bacterial life - - 103
,, classification of the bacteria - 100
Neutral tint reflector - - 7
,, ,, use of - - 22
Nicol's prism 5
Nitric acid produced by bacteria- - 103
Nucleus - 34
Nutrient solutions - - - - 176
Object glasses or objectives - - 2
,, ,, action of - - - n
,, ,, adjustment of high
power - 13
,, ,, aperture - - 12
,, ,, ascertaining magnifying
,, ,, modes of designating - 12
,, ,, penetration of - - 13
,, ,, resolving power - 13
Oidium lactis 85
,, lupuli 86
>, vini 87
Organisms in air at Old Carlsberg
Brewery - - - 157
in old wooden vessels - 161
in air - - - - 109
in water - - - 152
on barley - - - - 149
on hops - .-- 149
Ovary of hop ... - 147
Oxidation of hop resin - - - 148
Oxygen, influence on fermentation 38, 168
,, necessary to bacterial life - 104
Oxygenation of worts - - 38, 168
Page's gas regulator - - 130
Palea of barley-corn - - 138, 140
Panum, Prof. 63
Pasteur, L., methods of investigation - 128
,, researches in bacterial life 95
,, researches in fermentation
,, different types of brewing
yeast - - - - 59
Pasteur's flasks - - - - 65
,, lactic ftrment - - - 119
,, solution - - - - 176
,, viscous ferment - - - 115
Pasteurizing - - - - - 59
Pastorianus, S. - - 44, 74
fret - - - - 46, 164
Pedersen, Dr. .... -64
Pediococcus acidi lactici, albus and
Peligot on viscous fermentation - - 115
Pellicle formation - - - -72
Penetration of object glass - - - 13
Penicillium cladosporioides - 157
,, glaucum - - - - 87
Pericarp of barley-corn - - - 141
Phosphates in water and sugars - - 151
Phosphoretted hydrogen produced by
bacteria - - - - 103
Physical nature of yeast - - 27
Pipes, necessity for cleaning - 162
Pitching yeast appearance under micro-
scope - - 43
j } storage of - - - 179
wild yeasts in - -76
Pitted starch cells - 145
Plane Mirror ----- 9
Plaster of Paris, formation of Ascos-
pores on - -70
,, ,, storage of yeast with 180
Plate cultivation - - - 107, 153
Polarizing apparatus - - - - 5
Pollen cells on hops, etc. - - - 149
Preparing objects for the microscope - 19
Preservation of objects for the micro-
scope - - - 172
yeast - - - 180
Pressed yeast - - - - 180
Products of fermentation - - 41
Protein and proteid matter - - 31
Protococcus - - - 149, 153
Protoplasm 30, 84, 98
Puccinia graminis - - - - 83
Pure yeast culture - - - - 63
,, ,, ,, application to Eng-
lish process - 78
,, ,, ,, for use in brewery - 67
,, ,, ,, Hansen's work on - 64
,, ,, ,, Brown and Morris's
work on - - 78
Racking beer sediments, examination
Ranvitr Chamber - - - - 69
Raulin's fluid 176
Reagents, action on yeast - - - 36
,, or testing liquids - - 178
Red-rust of cereals - - - - 83
Reess, Dr., on the Saccharomycetes
44, 49, 5 2
,, "low" and "high" yeast,
varieties of one species 60
Regulator, Page's - - - - 130
,, ,, modified form - 132
Reinke on Sarcina - - - - 112
Resolving power - - - - 13
Retrograde forms of bacteria - - 101
Revival of old yeast - - - 168,179
Saccharomycetes - - - - 26
Saccharomyces apiculatus - - 50
hibernation of 51
Cerevisise - - 42
I. (Hansen) - 74
Coagulatus I. and II. - 47
Conglomeratus - 77
Ellipticus - - 45, 49
Ellipsoideus - - 49
I. and II.
Saccharomyces Exiguus - - 52, 77
glutinis - - - 157
Marxianus - - - 77
membransefaciens - 77
minor - - 50, 77
mycoderma - - 53
Pastorianus - - 44
I., II., and
III. (Hansen) - 74
,, Pastorianus fret - 45, 164
Sake - - - - - 85
Salicylic acid - - - 104, 126, 179
Sampling beer 55
Sarcina group no
,, aurantiaca, Candida, flava, and
maxima - - - - 112
,, hyalina, Reitenbachii, and
litoralis - - - - 113
,, found in English beers - - 113
,, conditions favourable to - 114
Schwann work on yeast - - - 29
Scotch yeast 42
Scutellum - - 144
Secondary fermentation of beers 39, 45
Sedimentary yeast - - - - 57
Sewage, decomposition by bacteria - 103
Sewer-gas in a brewery - - - 161
Sexual reproduction of moulds - - 83
Seynes De, ascospore formation - 36
" Sickness " caused by Ellipsoideus - 49
Slack malt, cause of faulty beer - - 167
Slime on water taps, organisms in - 97
Sphserotheca Castagnei - - - 92
Spherical aberration - - - - 9
Spirillum forms of bacteria - - 99
,, tenue and undula - - 126
Spongy iron as a filter - - - 155
Spontaneous fermentation - - 27, 165
,, ,, in Belgian
Spores of bacteria, germination of - 102
,, ,, probable effect of
electricity on 104
Sporulation of bacteria - - - 102
,, moulds - - 82
Stage condenser 4
,, movements - - - - 3
, , of microscope - - - - 1 , 3
Staining bacteria .... 107
Stand of microscope, I
Starch barley 143
,, in bacteria ? - - - 1 19, 122
,, other than barley starch - - 144
Steep-water, organisms in - - 97, 150
Stenchy fermentation - - - 167
Sterilized liquids - - - "3
Sterilizing liquids - - - - 65
Stops in microscope - - - - 4
Stone-square yeast - 42
Storage of pitching yeast - - - 179
Store yeasts considered as a mixture of
ferments - - 163
,, ,, signs of deterioration in - 164
Strobile of hop 147
Submerged Mucor - - - 90
,, Mycoderma Vini - 53
Sub-stage and condenser - - - 4
Succinic acid produced in fermentation 41
Sugar, used in brewing - - 150
,, ,, ,, microscopic ex-
amination of - - - - 151
Sulphur, alcohols in beer - - - 49
, , in waters - - - - 1 54
Sulphuretted hydrogen produced by
bacteria - - - 103, 154, 160
Sulphurous acid - - 104, 126, 162
"Surface" yeast - - - - 57
Swarm spores 83
Temperature favourable to growth of
Temperature favourable to growth of
High Yeast 58
Temperature favourable to growth of
Low Yeast - - - -37
Testa of barley-corn - - - 142
Testing-liquids - - 178
"Top "yeast 57
Torula forms ... - 91
Tyndall on bacteria in air - - 109
Tuborg brewery - - - - 63
Unit of measurement for microscopic
Uniformity of wort produces uniform
Ustilago carbo and segetum - - 91
Vacuum flasks - -66
Van Tieghem on fossil bacteria - - 108
Varieties of Yeast - - - - 42
Vegetable tissues, preservative solu-
tions for 177
Velten, M., on normal yeast - 77
Vesicles of hop - - - - 148
Vessels, brewery - - - - 156
Vibrio subtilis 124
Vinegar plant 119
Viscous ferments - - - - 115
in beer - - - 116
Water, bacteriological examination of- 153
,, filtration of - - - - 154
,, Heisch's test for - - 151
,, examination of sediments from - 152
,, scum on 154
Wild yeasts 75
,, ,, cause of faulty beer - - 165
Wine, barley 50
,, must, fermentation of - 104
Wooden vessels, danger when old - 161
Working distance of microscope -
Wort, variation in composition of
> oxygenation of
action of reagents on
behaviour during fermentation -
Burton, London, Scotch, Stone-
Carlsberg Low, No. I
,, No. 2
culture in gelatine wort
deterioration of - 35
,, effects on beer
effects of temperature on -
examination for wild forms
fractional ion of
Hansen's test for
" high " in relation to " low "
Yeast, history of identification -
,, ,, identification -
persistency of form -
,, physical nature of -
restoration of -
preserving samples -
,, signs of degeneration
views on foreign pressed -
Yellow mould of hops
Zopf, forms of bacteria
,, classification of bacteria -
57 Zygospores -
BEMROSE AND SONS, PRINTERS, DERBY AND 23, OLD BAILEY, LONDON.
THIS BOOK IS DUE ON THE LAST DATE
AN INITIAL FINE OF 25 CENTS
WILL BE ASSESSED FOR FAILURE TO RETURN
THIS BOOK ON THE DATE DUE. THE PENALTY
WILL INCREASE TO SO CENTS ON THE FOURTH
DAY AND TO $1.OO ON THE SEVENTH DAY
ri j O
LD 21-10m-5,'43 (6061s)