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Full text of "The microscope in the brewery and malt-house"

THE MICROSCOPE 



IN THE 



BREWERY AND MALT-HOUSE 




! 



FRONTISPIECE. 



THE MICROSCOPE 



IN THE 



BREWERY AND MALT-HOUSE 



BY 



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 
Chromo- Lithographs. 




X o n t> o n : 

BEMROSE & SONS, 23, OLD BAILEY; AND DERBY. 

1889. 

[ALL RIGHTS RESERVED.} 



Co 

,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. 

September, 1889. 



TABLE OF CONTENTS. 



CHAPTER I. 

PAGE 

THE MECHANICAL ARRANGEMENTS OF THE MICRO- 
SCOPE i 

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 



c.m.m 



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. 

CHAPTER IV. 

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. 

CHAPTER V. 
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. 

CHAPTER VI. 
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. 

CHAPTER VII. 
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. 

CHAPTER VIII. 
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. 

CHAPTER IX. 
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 

CHAPTER X. 

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. 

CHAPTER XI. 
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. 

CHAPTER XII. 
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 
Deteriorated Yeast. 

APPENDIX. 

A. - 170 

Microphotography apparatus, method. 

B. 172 

Preparing and Mounting objects for the Microscope. 

c. .75 

Various Preparations for Cultivation and Preservation of Organisms, 
etc. 

1. Gelatine for Cultivations. 

2. Nutrient Solutions, Raulin's fluid, Pasteur's solution. 

3. Preservative Solutions for Vegetable tissues. 

4. Cement for Mounting. 

D. 178 

Reagents or Testing Liquids, Dyes, Solvents, &c. 

E. i79 

Storage of Pitching Yeast. 

F. - - - 180 

Foreign Pressed Yeast. 

GLOSSARY 181 

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. 
2. Ditto. 

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). 
Sedimentary form. 
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). 

Barley Starch. 
Potato ,, 
Wheat 
Maize 
Rice ,, 

PLATE XVIII. (to face page 150). 
Hop dust. 

PLATE XIX. (to face page 150). 
Barley washings. 

PLATE XX. (to face page 152). 
Organisms, etc., in a water. 

PLATE XXI. (tofacepage 170). 
Micro-photograph Stand. 



DESCRIPTION OF WOODCUTS. 



PAGE 

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 

IA 



LITERATURE CONSULTED DURING THE 
PREPARATION OF THIS WORK. 



BOOKS. 

" How to work with the Microscope." Lionel S. Beale. 
11 The Microscope." Dr. Carpenter. 

" The Microscope in Theory and Practice." Nageli and 
Schwendener. 

" The Student's Handbook to the Microscope." A Quekett 
Club man. 

" Preparing and Mounting Microscopic Objects." Thomas 
Davies. 

" 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." 
Dr. Reess. 

" 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 
Balfour. 

" 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 
Chr. Hansen. 

" Infusoria." A. Pritchard. 

Transactions of The Laboratory Club, Vol. I. 

Transactions of The Burtonon-Trent Natural History Society, 
Vol. I. 



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. 



INTRODUCTORY PREFACE. 



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. 



Bridge Chambers, 

Burton-on- Trent. 



CHAPTER I. 



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 
adjustment. 

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- 
ment. 

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 
desirable. 

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 
is less. 

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 



Fig. 9. 

B. 






FAULTY. 



CORRECT. 



FAULTY. 



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 
Achromatic. 

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- 
formance. 

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 
unsuitable article. 

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. 



i6 



CHAPTER II. 



ON MANIPULATION 



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. 
3 



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 
draining rack. 

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, 
etc. 




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 
check. 

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 
eye. 

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 




PLATE I. 



A. eyep/ece & /'" object 



A. to B eyepiece & / '" object. . 



A ' foB eyepiece */6'" object, 
or B eyepiece &/6 '? object. - . 



A eyepiece 



immersion, . . _ 



j =/nches 






/ 


p 


y 


4 


HI! 






1 1 1 1 1 1 1 1 1 




































.-fanh'mfitr*.*; and Mi///metres 



--=i 00*% /coo* Inch x 40 



< f -' inch x too 



hs Inch 



Comparison of M/crometer lines with Metric asid inch Sca/es 



C.G.MATTHEWS.OEL. 



Bf!flO$. & 



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 
examination. 

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 
Society. 



26 



CHAPTER III. 



ALCOHOLIC FERMENTATION. 



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 
general character. 

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- 
mentation. 

(2) That this property of yeast is destroyed by a high 
temperature. 

(3) That the property is associated with particles that 
may be separated from the fluid containing them by an 
efficient filter, 

(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 
identified. 

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 
Protoplasm. 

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. 



BUD. 




VACUOLE 



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 
take place. 

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 

4 



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 
is considerable. 

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 



PLATE!!. 







Deuelopment of Yeast. 




i 



Sporulatton of Yeast . 

(after Reess) 



. 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 
deterioration. 

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, 



Alcoholic Fermentation. 



39 



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- 
aerated. 

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- 
gressing simultaneously. 

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. 



CHAPTER IV. 



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- 
ing science. 

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, 
etc. 

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 : 
Saccharomyces Cerevisiae, 
,, Pastorianus, 

,, Coagulatus,^ 

,, Ellipsoideus, 

,, Minor, 

and one or two species of rarer occurrence, 
Saccharomyces Apiculatus, . 

Exiguus, 

besides certain organisms which may at times act as alco- 
holic ferments, viz. : 

Mycoderma Vini, 
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 
present time. 

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 



PLATE ZZZ 




/. 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 
the former. 

Abnormal clearness and largeness of the vacuoles. 



44 Alcoholic Ferments of the English Process. 

Very distinct nuclei (except under certain conditions 
mentioned). 

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 
cells. 

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 

SACCHAROMYCES PASTORIANUS. 

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. 




Fig. 2. 




J.L.Wright, del. 



Deteriorated Yeast 

X 350 cjiamr' 



West, Newman 



PLATE: V 



Fiq.i. 




S . Pastor i an us. x 3f>O. 



Fig2 




Caseous Yeasts, x 360. 

L.H. N? I. ff.W. N2. 



Fig. 3. 





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 
very distinct. 

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 
form re-appeared. 

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 
order. 

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 

SACCHAROMYCES ELLIPSOIDEUS. 

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. 

SACCHAROMYCES MINOR. 

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 
said. 

SACCHAROMYCES APICULATUS, 

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, 

Fig. 17. 




J.E.W 



SACCHAROMYCES APICULATUS. 



though occasionally doubtful specimens of it occur in forced 
samples. 

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. 

SACCHAROMYCES EXIGUUS. 

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. 



MYCODERMA VINI. 

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 
same way. 

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. 

MUCOR RACEMOSUS. 

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. 



PLATE VI. 



Fiq. I. 




J C.Wright. del. 



Beer Deposit (Wild Yeasts &c.) 
x 300 



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 
forms. 



57 



CHAPTER V. 



RECENT RESEARCHES IN CONNECTION WITH LAGER-BEER 

YEAST, ETC. 



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 
dis-associated condition. 

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. 



rLATE. VIL. 



Fie I. 




300 



FIG 2. 



Sedimentary Form. 





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. 



J-E.WRIGHT. DEL. 



A. SONS.LITt 



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 
condition. 

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' 
yeast. 

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 
temperature. 

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 
of purity. 

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. 




PASTEUR FLASK. 



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. 



Fig. 19. 





Fig. 20. 




CHAMBERLAND FLASK. 



VACUUM FLASKS. 



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 




BOTTCHER CHAMBER. 

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 

Fig. 23. 




RANVIER CHAMBER. 

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 

ferments 

S. Cerevisise I. 

S. Pastorianus I. 

ii. 
in. 

S. Ellipsoideus I. 

II. 

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. 

ASCOSPORE FORMATION. 



Tempera- 
ture. 
Fah'. 


Tem- 
perature. 
C. 


S. Cerev. 
I. 
(Hansen.) 


S. Past. 
I. 
(Hansen.) 


S. Past. 
II. 

(Hansen.) 


S. Past. 
III. 
(Hansen.) 


S. Ellips. 
I. 
(Hansen.) 


S. Ellips. 
II. 
(Hansen.) 


99'5 


37-5 C. 


None. 

















96-898-6 


36-37 


29 hours. 

















95 


35 


25 














None. 


92-3 


33'5 


23 n 











None. 


31 hours. 


88-7 


3i-5 





None. 








36 hours. 


23 


86 


30 


20 hours. 


30 hours. 














84-2 


29 





27 


None. 


None. 


23 hours. 


22 hours. 


81-5 


27-5 





24 


34 hours. 


35 hours. 








797 


26-5 











30 








77 


25 


23 





25 hours. 


28 


21 hours. 


27 hours. 


73*4 


23 


27 


26 hours. 


27 











71-6 


22 











29 hours. 








64-4 


18 


50 


35 hours. 


36 hours. 


44 i> 


33 hours. 


42 hours. 


617 


16-5 


65 








53 








59 


15 





50 hours. 


48 hours. 





45 hours. 





51-8-53-6 


11-12 


10 days. 





77 n 








5'5 days. 


50 


IO 





89 hours. 





7 days. 


4-5 days. 





47'3 


8'5 


None. 


5 days. 





9 , 





9 days. 


44 '6 


7 





7 ., 


7 days. 





II days. 





37-4-39-2 


34 





H >, 


17 


None. 


None. 


None. 


32-9 


o-5 





None. 


None. 












* " 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- 
peratures. 

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 
very soon. 

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., 
4tneLiv. 1886. 

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. 
Ellips. I. 

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. 
FILM FORMATION. 



Tempera- 
ture. 
Fah 1 . 


Tem- 
perature. 
Gen 4 . 


S. Cerev. 
I. 

(Hansen.) 


S. Past. 
I. 
(Hansen.) 


S. Past. 
II. 
(Hansen.) 


S. Past. 
III. 
(Hansen.) 


S. Ellips. 
(Hansen.) 


S. Ellips. 
II. 
(Hansen.) 


104 


400 C. 

















None. 


96-8 100 '4 


36-38 


None. 











None. 


8-12 dys. 


91-493-2 


3334 


9-18 dys. 


None. 


None. 


None. 


8-12 dys. 


3-4 


78-882-4 


2628 


7-1 1 n 


7-10 dys. 


7-10 dys. 


7-10 dys. 


9-16 


4-5 


6871-6 


2O 22 


7-io 


8-15 


8-15 


9-12 


10-17 n 


4-6 


55 '4-59 


13-15 


15-30 


15-30 


10-25 n 


10-20 


15-30 


8-10 


42-8 44' 6 


6-7 


2-3 mths. 


1-2 mths. 


1-2 mths. 


1-2 mths. 


2-3 mths. 


1-2 mths. 


37'4-4i 


35 


None. 


5-6 


5-6 


5-6 


None. 


5-6 


35 '6 37'4 


2-3 





None. 


None. 


None. 





None. 



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 
pitching yeast. 

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 
shape. 

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 
Maltose. 

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 
process. 

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 
fermentation. 

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." 



8o 



CHAPTER VI. 



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 
same cause. 

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 
7 



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 
air. 

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 
distinctly unpleasant. 

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 
ferment. 

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- 
yeast. 

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 



F/C.l. 



FlC.2. 





Oidium Laciis(Reess& l M& l L) 
F/c-J 



Pen/oil Hum Glaucum (Maddox) 
r/c.4. 




Mucor Racemosus. 



Fie 5. 



Mucor Racemosus (Submerged) 






b c 

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 
atmospheric conditions. 

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 
cells. 

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 
Sporangia. 

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 
alcohol. 

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 
in question. 

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 
subsist. 

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 
unassisted eye. 

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 
facilitated. 

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 
Racemosus. 

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 
a film. 

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 
mould growth. 

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. 



95 



CHAPTER VII. 



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 
product. 

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 
ferments. 

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- 
fication. 

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 
enormous length. 



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 

cocci. 

,, II. BACTERIACE^: Cocci, short rods (Bacteria), long 
rods (Bacilli), long threads (Leptothrix) ; no 
spirals. 

,, 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 
exhibiting false-branching. 

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 : 



Fie. I. 



FIG. 2. 



> V 



/' I / 



\\ \ \i 

\ \ ', 



s ', 




-ix Dichoiomcu $OQ Clcud. Dichotomy : 

(after ZopfJ (aft". z opf) 

:. J. F/c.4. FIG. 5. 



* 



98 

ii ; 

99990996 



Fie. 6 



F/c.7. 




Crenothrix Kuhmasia 
(after Zopf) 



Bacterium Termo 6 -^ 
(after Cohn) 



J E WRIGHT DEL. 



Stf/-/.y /./T" 



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 
organism 

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 
threads. 

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 
magnified. 

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 
use. 

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 
range. 

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 

bacteria. 
4. The behaviour of the organism in relation to 

Oxygen. 

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 
chloride solution. 

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 
equal squares. 

(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- 
measures. 

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. 

Winter 49 

Spring 85 

,, 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). 
Sarcina. 

The Viscous ferments. 
Bacterium Aceti. 

,, Pasteurianum. 

,, Xylinum. 

MICRO- BACTERIA (short rods). 
Bacterium Termo. 
,, Lactis. 

Pasteur's lactic ferment. 
Bacterium Butyricum (also called Clostridium 

Butyricum and B. Amylobacter). 
DESMO- BACTERIA (including long and sliort threads). 
Bacillus Subtilis. 

Ulna. 

Leptothrix. 

SPIRO-BACTERIA (Spirals). 
Spirillum Tenue. 
,, Undula 

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 cerevisiae. 
Pediococcus acidi lactici. 
Pediococcus albus. 
Sarcina Candida. 
Sarcina aurantiaca. 
Sarcina flava. 
Sarcina maxima. 

* " 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 
pellicle. 

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 
Frankel.* 

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. 



PLATE 1L. 




Sarcina Maxima ' 
(after Lindner) 



jw 




Fed. Acidi. Lactici (? 
(after Lindner) 



Viscous Ferment- *-*- a 
(after PasteurJ 






Bacterium Aceti 
(afrer Pasteur) 






Lactic Ferment T* 
(after Pasteur) 



Bact. Lacf/s 












Bacterium Bufyricum 3f. 

[0. 




B. Lepfofh 



Bac. Subtil is 



Spirillum Tenue 



X? 

/ 



Bac.Ulna^r 



Spirillum Urdu/a 



J.E.WRIGHT DEL. 



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 
lactici. 

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 
9 



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 
apply : 

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. 

Viscous FERMENTATION, 

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 

MYCODERMA ACETI, 

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 
effect. 

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 
its growth. 

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. 

BACTERIUM PASTEURIANUM. 

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 
generations. 

BACTERIUM XYLINUM 

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 
two organisms. 

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 
lactici. 



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, 

BACTERIUM TERMO. 
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. 

BACTERIUM BUTYRICUM, 

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, 
Chapter X.) 

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. 

BACILLUS SUBTILIS. 

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 
chapter. 

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 
above-mentioned. 

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. 

BACILLUS ULNA, 

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. 

BACILLUS LEPTOTHRIX 

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.) 
Bacterium pyriforme. 

,, fusiforme (Warming). 
,, Kochii. 

,, Carlsbergense (resembling B. butyricum). 
They do not appear to us, however, to call for more than 
passing notice. 

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 
comparable. 



128 



CHAPTER VIII. 



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 
product. 

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 
of yeast. 




forcing Tray in working order, 
(from a photograph] 




J.E.WR/GHT. 



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 
" forcing." 

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. 

10 



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. 



c 



S 



A 




PAGE'S REGULATOR. 



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 

Fig. 26. 

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 
examined. 

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- 
ably fostered. 

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 
commences. 

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 
then noted. 



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 
other sub-class. 

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 



PLATE XU 




FiG.3 



FIG. 6, 




"Forced Beer'' sediments 



J.E.Wnqhl.del. 



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 
altogether vitiated. 

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.) 



138 



CHAPTER IX. 



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 

Fig. 27. 




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 



140 



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, 

Fig. 28. 




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. 



Fiy. 2 



Fig. J. 




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 



PLATE. 




Fig. I. Pericarp 





F,g2. Testcu 



Fi g <*>. Diagram Section, 
(after Hohner.) 



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. 



J.E.Wfl/GHT.DEL 



SflrfiO$ & SOf/S.L/TP 



PLATE. IY 



Sect /on of a Bar/ey Corn in the p/ane of the 
ax/s and trough She -furrow. 
Reduced from C. 



C 




D 



D Corn bristle 

E. Pcuppus 

F. Pigment siring 



B. Endosperm 

6 1 A/eurone layer 

62 Starchy mattet 
6s Empty cells 



C Germ 1 - pourts 
a Scutelfum 
ce A cr asp/re 
CJ Rootlets 



J.C.WRIGHT DLL. 



B/*#0$ & SOf/S.l/r? 



Fie. I. 




From a Photograph 



Transverse sections of Barleycorn 



J.E.Wff/CHT. DEL. 



SONS.LITV 



The Anatomy of the Bar ley-Corn. 



143 



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 

Fig. 29. 




ALEURONE CELLS. 



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. 




Barley Starch. 




Potato Starch. 



' 



3 






'~ / 




Wheat- Starch. 



1 

) a 








v 






Starch 



Rice Starch. 



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 
days. 

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 
purpose. 

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. 
II 



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. 



147 



CHAPTER X. 




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 

Fig. 30. 







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 
considerable profusion. 

In Plate XVIII. are shown examples of most of these 
objects. 

a. Ferment cells. 

b. Bacteria. 

c. Crystals. 

d. Particles of Earth and Siliceous matter. 

e. Spicules, probably part of the Hop plant. 

f. Mould-spores, probably of Ustilago and some species 

of Fusarium. 

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. 

SUGAR. 

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 



PL 



8 



to 



V 



/ 






o 






Organisms & c found in Hop dust, 
x sco 



J. . WRIGHT.DEL. 



BF.MflOSf & SON3.1-IT'. 



PLATE ZZK. 




Q 

Q * 

9 



W 

S^^T 



o 






/ 1 * 





t 





Organisms found in basleu dust. 

*. 300 



G.G MATTHEWS. DEL. 



BEMROSE & 



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 
as above. 

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 
impure. 

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. 



^^ 

O 













i 







Organisms ^ found in sample* of Drinking Water. 



J . Wff/CH T. DEL . 



& SONS. 



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 
the bottom. 

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. 



156 



CHAPTER XL 



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 
minimum. 

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 
again formed. 



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. 

SACCHAROMYCETES. 

S. cerevisise. 
S. ellipsoideus. 
S. exiguus. 
S. Pastorianus. 
S. mycoderma. 
S. apiculatus. 
S. glutinis. 

MOULDS. 

Eurotium aspergillus glaucus. 
Aspergillus fumigatus. 
Penicillium glaucum. 

,, cladosporioides. 

Mucor racemosus. 
,, stolonifer. 
Botrytis cinerea. 
Cladosporium herbarum. 

* Meddelelser fra Carlsberg Laboratoriet, 1879 and 1882, vol. I, part 4. 



158 Brewery Vessels, etc., etc. 

Dematium pullulans. 

Oidium lactis. 

A species of Dendrochium. 

,, ,, Monilia. 

,, ,, Arthrobotrys. 
Indeterminate mycelium. 

FORMS NOT CLASSIFIED, POSSIBLY MOULDS. 

Cells like Saccharomyces cerevisiae. 

,, Chalara. 

Red cells resembling Saccharomycetes. 
Small round cells of a "torula" form. 

BACTERIA. 

Bacillus subtilis. 

,, ruber. 
Bacterium Kochii. 

,, pyriforme. 

,, Carlsbergense. 
Mycoderma aceti. 

,, Pasteurianum. 
Spirillum tenue. 
Yellow bacillus. 
Sarcina. 
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 
contained. 

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 
contamination. 

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 : 

Sarcina. 
Bacillus ulna. 



12 



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 



CHAPTER XII. 



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 
of. 

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 
causes. 

The well-known causes of mishap to the brewer stated 
above in general terms, are : 

Impure steep water. 
Indifferent or bad barley. 
Unskilled malting. 
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 
quantity. 



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 

Sluggish fermentations. 

Imperfect attenuation and cleansing. 

Improper flavours. 

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. 



170 



APPENDIX A. 



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 
by drawing. 

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 



PLATE XXI. 




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 Camera. 

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 
light. 

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 
Camera. 

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. 



APPENDIX B. 



ON PREPARING AND MOUNTING OBJECTS FOR THE 
MICROSCOPE. 

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 
before. 

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 
turpentine. 

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 
extemporized. 

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. 



APPENDIX C. 



VARIOUS PREPARATIONS FOR THE CULTIVATION AND 
PRESERVATION OF ORGANISMS. 

I. GELATINE FOR CULTIVATIONS. In making this 
preparation, use preferably the transparent white thin- 
leaved gelatine. 

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 
following : 

"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. 

Raulin's Fluid. 

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 

Pasteur's Solution. 

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 
Ammonic Sulphate. 



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. 

Goadby's Fluid. 

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 
germinating Barley. 

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. 
13 



178 Appendix D. 

APPENDIX D. 



REAGENTS OR TESTING LIQUIDS. 

Iodine Solution. 
(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. 

Methyl-Violet. 
(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. 

Weak Ammonia. 
(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 

APPENDIX E. 

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. 



APPENDIX F. 



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 
with paraffin-wax. 



GLOSSARY; 

OR, 

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 

coloured edges. 
,, 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 

dispersible. 
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 

butyricum. 

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- 
fungi. 

BACTERIACE^E, term applied by Zopf in his classification of the Bacteria, to 
a group including a variety of forms, and amongst them short 
rods. 
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. 

0. 

CAMERA LUCIDA, a light-reflecting apparatus, applied to the microscope 

for drawing objects. 
CAPILLARY, hair-like. 



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. 

Strobile. 
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 

liquids. 

CHLOROPHYLL, the green colouring matter of plants. 
CHROMATIC ABERRATION, See Aberration. 
CHROMOGENOUS, applied to the bacteria having the power of producing 

colour. 
CILIUM-A, minute hair-like filaments which act as the motile organs of 

bacteria, etc. 

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 

yeast 
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 

micrococci. 
Coccus (a berry), term applied to the small rounded form of many 

bacteria. 
CONCAVE (hollowed), applied to lenses arid mirrors having a hollowed 

surface. 
CONDENSER, an apparatus for concentrating light on an object under 

microscopic examination. 

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 

in cones. 



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 

cooled. 

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. 

D. 

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 

markings. 

DIPLOCOCCUS, two rounded bacteria more or less closely joined together. 
DORSAL, applied to the outward side of a seed in situ. 

E. 

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 
living things. 

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 
Japanese ferment. 

P. 

FIELD, term applied by microscopists to that part of the slide under 
observation, seen at any given time through the instrument. 



Glossary. 185 

FLAGELLUM, a whip-like appendage possessed by many microscopic 

organisms, enabling them to move freely in liquids. Syn. 

Cilium. 
Focus, the point to which rays of light or heat are concentrated by a lens 

or mirror. 
FORCING TRAY, apparatus used for keeping vessels at a constant degree of 

warmth. 
FORCING FLASK, a glass vessel for testing beer or other liquids on the 

forcing tray. 

FUNGUS, a class of non-flowering, leafless plants (Thallophytes). 
FUSARIUM HORDEI, the red mould of barley, having spindle-shaped or 

crescent spores. 

G. 

GLANDS, applied, in botany, to special cells containing particular substances, 
such as oil, resin, etc. 

H. 

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. 

I. 

INFUSORIUM-A, microscopic organisms found in water and other liquids. 

K. 

KOJJ, macerated rice containing fungus spores, used by the Japanese as a 
ferment in making Sake, and bread ; also in the manufacture 
of ''Soy." 

L. 

LAGER, term applied to store beer brewed on the " low'' or bottom " fer- 
mentation system. 

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. 

M. 

METRE, the standard of length of the French metric system : approximately 

39-37 inches. 

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. 

N. 

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. 



Glossary. 187 

O. 

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. 

P. 

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, 

including barley. 

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 

certain yeasts. 
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. 

B. 

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 

bright surface. 
REFRACTION, the bending of a ray of light on passing into a medium of 

different density. 
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 

cells. 

,, EXIGUUS, a ferment of small size. 

,, MARXIANUS, a ferment described by Marx. 

,, MEMBRANjEFACiENS, a ferment forming a film or mem- 

brane. 

,, MINOR, a ferment of a small rounded form. 

,, PASTORIANUS, a ferment first described in detail by 

Pasteur. 
,, GLUTINIS, a ferment giving rose-coloured slimy spots on 

potato, etc. 

SAKE, a fermented liquid made in Japan. 
SARCINA AURANTIACA, a small bacterium producing a golden yellow 

appearance. 

,, 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. 

Hop mildew. 

SPICULE, a minute slender point. 

SPIRILLUM TENUE, a thin spiral bacterium found in decomposing liquids. 
,, VOLUTANS, a spiral revolving bacterium found in decomposing 

liquids. 
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 

life. 

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. 



T. 

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. 

u. 

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 
on cereals. 



190 Glossary. 

V. 

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 

vegetables. 
VIBRIO, a term applied to the short bacteria which have a rapid movement. 

Y. 

YEAST-FLASKS. Syn. forcing-flasks : a misnomer. 

Z. 

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 
fructification. 



INDEX. 



PAGE 

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 
Aerobian ferments 
Age of Yeast .... 
Air, contamination of in Brewery 

,, filtration of 

,, organisms in 
Albuminoid matter - 
Alcoholic fermentation 
Aleurone cells - ... 
Alt Carlsberg Brewery 
Alternation of generation - 
Ammonia, for clearing resin 

slides - 
,, 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 

Antiseptics 

Aperture, angular 

Apiculatus 

Aplanatic 

Appert's process .... 
Aroma of Hops ..... 

Arthrobotrys 

Artificial illumination for Microscope - 



62, 



26, 



38, 1 68 
54, 72 
35 
1 60 

159 
109 

40 

- 143 

- 63 
' 83 

from 

178 



'1 

52 
138 

12 
175 
155 
126 

12 

50 
IO 



'1 



Ascospores .... 

,, formation, table of - 

,, of Moulds - 

ASCIIS 

Aspergillus fumigatus 

,, glaucus - 

,, ,, eurotium form 

,, niger 

Asphalt varnish ... 

Assay flask .... 
Atmospheric germs 
Awn of the Barley-corn 



Bacillus amylobacter - 

,, leptothrix 

,, ruber - 

,, subtilis- 

,, ulna .... 

,, formation of spores 
Bacteria 

,, affinity for Oxygen 

,, associated with Brewing 

,, Cohn's classification of - 
colour-producing - 
dimensions of 



26, 



PAGE 

' 36 

- 71 

- 8 9 

- 82 

- 157 

- 8 9 

- 8 9 

- 8 9 
' 175 
" 6 7 

- 109 



- 122 



124 

125 

102 

95 
104 

I JO 

98 
1 02 
97 



96 
126 
104 

105 
104 
TOO 
106 



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 



192 



Index. 



PAGE 

Bacteria, spores of, not easily killed - 105 
staining .... 107 
structure - - - - 98 
temperature favourable 

to - - - - 105, 158 
variation of form - - - 99 
zoogloea form - - -102 
Zopfs classification of - - 100 

Bacteriaceae 100 

Bacteriological examination of water 153 
Bacterium aceti - 

butyricum - 

Carlsbergense - 

fusiforme - 

Kochii - - - 

lactis 

,, in beer 
Pasteurianum 
pyriforme - 
termo 
xylinum 

Baker's yeast .... 
Barley, black mould of 
,, blue mould of 
,, red mould of 

Barley-corn, absorption of water by 
anatomy of 
changes during germina 

tion - 

external structure - 
general appearance of 
germinal parts of - 
internal structure - 
number of rootlets - 
sections of 
starchy part - 
Barley dust, organisms in - 
Barley-starch .... 
Barley-wine .... 
Bary, De, on Sarcina 
Beale's neutral tint reflector 
Beer, Belgian - 

bottled, sediments 
forced samples - 
lager 

maize .... 
racking deposits 

Beggiatoa 

Belgian Breweries, apiculatus in - 
Bersch on Sarcina in beer - 
Binocular Microscope 
Bisulphite of Lime as an antiseptic 
,, ,, use in brewery 

Black mould of Barley and Hop 
Bladdery fermentations 
Body of the Microscope 
Boiling, for sterilization 

,, fermentations 
Borax, use of 

Botrytis cinerea - - - - 
Bottcher chamber 
Bottled beer, sediments 
Bottom yeast .... 
Bract and Bractlet of Hop - 
Brefeld on Alcoholic ferments 
Brewers' yeast, microscopic 
ance of 



149: 



117 

122 
126 
126 
126 
1 2O 
121 

118 

126 

121 
II 9 

59 
91 

87 

93 

140 

138 



140 
138 
144 
142 
H5 
173 
142 
165 
143 

- 50 

- 112 

- 7 

- 27 

45,47 

- 135 

- 58 

- 27 

- 55 



Ill 

2 

126 

162 

91 

167 

136 
167 
179 

1^7 



65, 



- 45. 47 

- 57 

- 147 

- 91 
appear- 

- 41 



PAGE 

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 

Cerevisia 27 

Chalara mycoderma - - - - 86 

Chamberland filter - - - - 155 

,, flask - - - 66 

Cheese, ripening of, due to bacteria - 97 
Chemical nature of yeast - - -31 

Chica 27 

Chlorophyll - 81 

Chromatic aberration - - - 10 

,, ,, correction for - n 

Cilia of bacteria - - - - 98 

,, moulds - - - - 82 

Circulation of liquids in barley-corn - 141 

Cladosporium herbarum - - - 157 

Cladotrichese 100 

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 



Index. 



193 



PAGE 

Cleansing media - - - 162 

Clostridium butyricum - - 122 

Coagulatus, S. - - - 48 

Coarse adjustment of microscope - 2 

Coccacese - - 100 

Coccus 98 

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 

Corn-bristle 139 

Correction for chromatic aberration - 10 

,, spherical aberration - 10 

,, thickness of cover-glass 13 

Cover-glasses 7 

Crenothrix Kuhniana - - - 101 

Cultivation of bacteria - - - 105 

,, ,, gelatine for - 175 
,, ferments 
,, moulds 
,, pure growths 



Dallinger, Dr., recent work of 

Dammar, for mounting 

Dead cells 

Decomposition due to Bacteria 

De Bary, Dr. - 

D^e Seynes on Ascospores - 

Defining power of object-glass 

Dematium pullulans - 

Dendrochium - 

Desmids in water 

Desmobacteria - 

Deteriorated yeast, effects of using 

Deterioration of yeast 

,, ,, causes of - 

Development of yeast 

Diameter of objects, method of ascer- 
taining ... 

Diaphragm 

Disastase - 

Diatoms in water 

Diplococcus 

Diseases produced by the Schizomy- 
cetes - 

Disinfectants in a Brewery 

Dissection of Barley-corn - 

Dorsal side of Barley-corn - 

14 



PAGE 

Drams of Brewery - - 160 

Draw-tube of Microscope - - - 6 

Drawing, desk for - - 22 

,, objects from the microscope 23 

yeast 44 

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 

Endospore 36 

Engel on S. Minor - - - - 50 

,, spore formation - - - 36 

English beer, the alcoholic ferments of 40 

Epithelium 144 

Erector 18 

Erysiphe Tuckeri - - - - 87 

Eurotium aspergillus glaucus - - 89 

,, Oryzse ... 85 

Evershed, VVallis - - - - 164 
Exiguus, S. 52, 77 

Eye-lens ------ 2 

Eye-piece 2 

,, ,, action of - - n 

,, ,, micrometer - - - 24 

,, ,, mode of designating - - 12 



- 61 


Ferment, definition of term - - 40 


94 


Fermentation, abnormal - - - 167 


- 63 




acetic- - - - 117 






alcoholic - - - 40 






"bladdery" - - 167 


- 60 




" bottom " or " low " 57 


- 173 




butyric - - - 122 


43 




cause of - . - 28 


- 97 




conditions favourable to 37 


97, 112 




"high" or "top" - 57 


- 36 




lactic - - - - 120 






moulds producing 85, 90 


- 158 




of beer - - 27 


- 158 




of milk - - - 97 


- I5 2 




of wine - - 27, 44, 49 


- 98 




products of - 41 


- 164 




spontaneous 27, 165 


- 35 




secondary - - - 45 


163, 166 




stenchy - - - 167 


- 34 
cer- 


Ferments, species identified by Hansen 70 
in Brewers' yeast 41, 164 


24 


,, unorganised - - -41 


- 4 


Field lens 2 


- 41 


Film formation 72 


- !5 2 


table .... 74 


- 99 


Film of dirt in Brewery pipes - - 162 


my- 


Filtration of water - - - 154 


- 97 


Fine adjustment of Microscope - - 2 


- 162 


Fission-fungi - - - - - 96 


- 141 


Flagella of bacteria - - - - 98 


- 138 


,, moulds 83 



194 



Index. 



PAGE 

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 

Focussing 20 

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 

Germ -96 

,, 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 



Hsematimeter 



description of 



65 



PAGE 

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 

yeast 

Holzner & Lermer, work on barley 

com - .... 
Hop - 

aroma .... 
black mould of - 
"condition" 

cone 

dust, organisms in 
microscopic examination of - 
mildew - ... 
oil, change due to age 
resin ----- 
vesicles 

yellow mould of - 
1 1 op -sickness - ... 
Huth, S. Von, on Sarcina - 
Hyphse 



57 
72 

146 

147 
148 

9i 
147 
H7 
149 

92 
148 
148 
148 

93 
150 
in 

82 



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 

119, 122 



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 



Index. 



195 



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 

Leptotrichese 100 

Leptothrix 100 

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 

Lodicules 139 

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 

Microbacteria 98 

Microbe 96 

MicrOcoccus 98 

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 

compound I 

magnifying power - - 24 

makers - - - - 14 



mechanical 

of 
monocular 

position of 



arrangement 



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 

Millimetre 25 

Minor, S. 50, 77 

Miquel's experiments, organisms in 

air - - 109, 156 

Miquel's experiments, organisms in 

water 153 

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 

Mucedines 80 

Mucorini 80, 101 

Mucor mucedo 90 

,, ,, submerged as a ferment 91 
,, racemosus - - - - 89 
,, ,, submerged as a ferment 

54 



,, stolonifer 
Must, fermentation of 
Mycelium - 
Mycoderma aceti 
,, vini 
Mycoprotein 



90 

- 157 

- 104 

- 82 

- "7 

: II 



196 



Index. 



PAGE 

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 

power 24 

,, ,, 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 

29, 40 
,, 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 

cerevisise 112 

Peligot on viscous fermentation - - 115 
Pellicle formation - - - -72 
Penetration of object glass - - - 13 
Penicillium cladosporioides - 157 

,, glaucum - - - - 87 

Perithecium 89 

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 

Plumula 144 

Polarizing apparatus - - - - 5 
Pollen cells on hops, etc. - - - 149 

Polymorphy 83 

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 

Pseudospores 93 

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 

of 55 

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 

Refraction 9 

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. 



(Hansen) 



75 



Index. 



197 



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 

Schizomycetes 95 

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 

Slips 7 

Smut 91 

Soy 85 

Sphserobacteria 98 

Sphserotheca Castagnei - - - 92 

Spherical aberration - - - - 9 

Spirillum forms of bacteria - - 99 

,, tenue and undula - - 126 

Spirobacteria 98 

Spongy iron as a filter - - - 155 

Spontaneous fermentation - - 27, 165 

,, ,, in Belgian 

breweries 78 

Sporangium $2 

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 



PAGE 

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 

Bacteria 105 

Temperature favourable to growth of 

High Yeast 58 
Temperature favourable to growth of 

Low Yeast - - - -37 

Testa of barley-corn - - - 142 

Testing-liquids - - 178 

Thallophytes 26 

"Top "yeast 57 

Torula forms ... - 91 

Tyndall on bacteria in air - - 109 

Tuborg brewery - - - - 63 



Unit of measurement for microscopic 

objects 25 

Uniformity of wort produces uniform 

yeast 168 

Ustilago carbo and segetum - - 91 



Vacuoles 33 

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 



198 



Index. 



Working distance of microscope - 
Wort, variation in composition of 
> oxygenation of 



Yeast 



action of reagents on 
behaviour during fermentation - 
brewers' - 

Burton, London, Scotch, Stone- 
square - 

Carlsberg Low, No. I 
,, No. 2 
Composition of 
culture in gelatine wort 
deterioration of - 35 

,, effects on beer 

drawing - 

effects of temperature on - 
examination for wild forms 
fractional ion of 
growth of 
Hansen's test for 
" high " in relation to " low " 



. 


PAGE 

9 


Yeast, history of identification - 


PAGE 

- 28 


F - 


168 


impurity of 


- 41 


38, 


1 68 


life-history 


- 34 






microscopic characteristics 


- 43 






,, ,, identification - 


- 32 


- 


40 


persistency of form - 


76, 163 


- 


36 


,, physical nature of - 


- 27 


ion - 


39 


restoration of - 


168, 179 




4i 


preserving samples - 


- 180 


tone- 




,, signs of degeneration 


- 43 




42 


sporulation 


- 36 


63 


. 75 


storage of 


- 179 




76 


structure of 


- 32 




3 1 


views on foreign pressed - 


- 180 


- 


68 


wild 


75 


163, 


166 


Yellow mould of hops 


- 93 


eer - 


169 






- 


44 






. 


38 






. 


76 


Zooglaea 


- IO2 


- 


164 


Zoospores 


81,83 


. 


34 


Zopf, forms of bacteria 


99, 101 


. 


70 


,, classification of bacteria - 


- 100 


v" - 


57 Zygospores - 


- 83 



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