Chapter V
., “low” yeasts, to be preserved in their state of “lowness,” must be submitted to often-repeated growths—every fifteen days in winter and every ten days in summer, that is to say, they must be grown afresh after each of these intervals. If this is done, there will be no reason to apprehend the formation of aërobian ferments, which, as we have stated before, may embarrass us by transforming our “low” yeasts into “high” yeasts.
Footnote 165:
It has been observed by brewers that, sometimes, without any apparent cause, a yeast suddenly becomes inactive and fermentation ceases. Accidents of this kind may probably be explained in the same manner as the facts of which we are speaking. If a wort has not been aerated, or if it has been deprived of oxygen by a commencing development of microscopic organisms, the yeast formed in it will be very inferior, and the fermentation may stop at its commencement or soon afterwards. In such a case, an aeration of the yeast and wort would be the best remedy.
Footnote 166:
PASTEUR, _Comptes rendus de l’Académie des Sciences_, vol. lii. p. 1260, and _Études sur le Vin_, 2nd Edition, p. 277.
Footnote 167:
We may here remark that the system of gutters in the above apparatus is much simpler than that described in connection with Figs. 76 and 77. The water which falls on the cover is carried off, when the gutter is full, by a circle of grooves, inclined so that the streams running from them meet and form more readily a sheet of water, which flows over the exterior surface of the cylindrical vessel.
Footnote 168:
[It will be well for the reader to bear in mind, that the word “strength,” used by Pasteur many times in this chapter, has a different meaning to that which attaches to it in the minds of English brewers, who in nearly every case use it in reference to _original gravity_, while the author employs it, in this chapter, at any rate, to denote the _palate characteristic of strength_, in other words _palate-fulness_. For this reason we have thought it best in many cases to actually substitute the term “palate-fulness,” or “body,” for the literal translation of the French word “force.”—F. F.]
Footnote 169:
[As some confusion has existed in the nomenclature of these salts, it may be as well to offer some explanation.
The salt here used for absorbing oxygen was discovered by Schützenberger, and named by him _hydrosulphite of soda_. It no longer now goes by that name, being called _hyposulphite of soda_, NaHSO_{2}.
The salts formerly known as _hyposulphites_ are now called _thiosulphates_, as Na_{2}S_{2}O_{3}.
Thus to put them together we have:—
Hyposulphite (Hydrosulphite) NaHSO_{2} Bisulphite NaHSO_{3} Thiosulphate (Hyposulphite) Na_{2}S_{2}O_{3}
The thiosulphates were formerly regarded as containing the elements of water in their composition, thus:—Na_{2}H_{2}S_{2}O_{4}, which being halved would give NaHSO_{2}, isomeric with hyposulphite, as Pasteur says. It is further to be observed that Pasteur uses the old notation, in which the number of atoms of sulphur and oxygen are the double of what they are in the new.—D. C. R.]
Footnote 170:
SCHÜTZENBERGER, _Comptes rendus de l’Académie des Sciences_, vol. lxxv., p. 880.
Footnote 171:
M. Schützenberger applies the term _saturated_ to a solution of hydrosulphite prepared thus, or very nearly so; a current of sulphurous acid is passed through a solution of commercial bisulphite of soda, to excess; 100 c.c. (3-½ fl. oz.) of this solution and 30 grammes (46 grains) of zinc filings are put into a small flask, so as to completely fill it; the bottle is corked up and the mixture is shaken briskly for about a quarter of an hour. Lastly, the contents of this flask are poured into a large 2-litre flask, with water and containing milk of lime, prepared by mixing 100 grammes (3·2 troy oz.) of quicklime in the water just before it is used. The whole is shaken briskly for some minutes and then left to settle. The supernatant liquid soon becomes bright. This is the hydrosulphite; but in this state it is too concentrated; and should be syphoned into another 2-litre flask half full of water. In the alkaline condition this salt absorbs gaseous oxygen much less rapidly than in the acid, so that the liquids will retain their strength much longer, if they are kept in well-corked bottles.
Footnote 172:
The numbers _n_ and _n´´_ will vary as the wort, or liquid which we have to test, is perfectly neutral or otherwise. Should it be acid _n´´ n_, should it be alkaline _n n´´_. This would be a very exact method of estimating the acidity or alkalinity of any coloured liquid.
Footnote 173:
[The Balling saccharometer being almost unknown in England, we may explain that its indications are for percentages of sugar in saccharine solutions, or of extract in worts; 17·9° Balling, therefore, means 17·9 per cent. of sugar or extract in the respective liquids.—F. F.]
Footnote 174:
Experiments made, at our request, by MM. Calmettes and Grenet, at Tantonville; in Tourtel’s brewery.
Footnote 175:
See foot-note, page 367.
Footnote 176:
[For non-technical readers we may explain the expressions “gathered,” here used, and “turning out,” used on page 365. “Turning out” describes the operation of emptying the _copper_ contents into the _hop-back_, or the _hop-back_ contents on to the _coolers_. “Gathering” refers to the time when the worts are finally intermixed and _weighed_, prior to the commencement of vinous fermentation.—F. F.]
Footnote 177:
We know also from the direct experiments of M. Schützenberger, performed on aerated water with which yeast had been mixed, that yeast causes all the oxygen in solution to disappear very quickly, so that hydrosulphite gives no evidence of a trace. (See SCHÜTZENBERGER, _Revue scientifique_, vol. iii. (2), April, 1874).
Footnote 178:
[The bottling needle (_foret â aiguille_) is a contrivance for permitting a cork to be driven into a bottle completely filled with liquid, without bursting the bottle. It consists of a slightly-tapering iron pin about 1/8th inch in diameter and 2 inches in length, somewhat flattened, and slightly curved throughout its entire length, with a groove running down one side from end to end, the pin being jointed with a ring, like a common ring cork-screw. In using it the pin is driven into the bottle alongside the cork, thus allowing the excess of liquid to escape as the cork advances. When the cork is completely home, the needle is withdrawn, and the elasticity of the cork enables it to fill up the space left, so that we have the bottle corked air-tight, and no air left between the cork and liquid.—D. C. R.]
Footnote 179:
We have remarked in our observations on No. 6 of Plate I. (p. 6) that amongst the amorphous granular deposits of wort and beer we often find minute balls of resinous and colouring matter, perfectly spherical and very dense, which if the liquids be shaken up will render them very turbid, but which readily and rapidly deposit again, without remaining in suspension in the least. Such then is the form in which the deposits of wort in course of fermentation are precipitated, when the wort has been freely exposed to oxygen. One day in the laboratory we were desirous of starting a fermentation in a vessel capable of holding 12 hectolitres (264 gallons). But as we only had at our disposal a copper capable of holding 2-½ hectolitres, we procured the wort from a neighbouring brewery in two barrels of 6 hectolitres each. This wort we re-heated, in portions, in our 2-½ hectolitre copper, a treatment which had the effect of oxidizing the wort more than it would have been in the brewery. In this case the beer fell remarkably bright, and the cells of yeast were accompanied by the deposit of minute agglomerations sketched in Plate I., No. 6. We have repeated this experiment on a smaller scale and have obtained the same result.
Footnote 180:
It is evident that this arrangement may be modified in many ways. Any of the ordinary worms, or, generally speaking, any of the more modern refrigerators invented during the last few years, may be adopted. The only point that is of importance is the preservation of the purity of the wort during cooling.
The Baudelot refrigerator is extensively adopted in France; for this reason we used it in our experiments at Tantonville. We might equally well, by enclosing the worm in a casing of sheet iron or tinned copper, pass our wort over the exterior of the tubes, the cold water passing through them. The wort would cool quicker in this way than with the arrangement described in the text, and if we arrange to admit only pure air into the case, always under conditions of purity. The aeration, moreover, could be made as much as we wished.
Footnote 181:
This arrangement limits the proportion of oxygen that may be introduced into the wort by direct oxidation. But it would be easy to increase this at will, by causing the wort as it comes from the copper and the hop-back to pass into a cylinder turning horizontally on its axis and furnished with blades fixed inside, so as to divide the wort and bring it better into contact with the air in the cylinder. Instead of a revolving cylinder we might use a fixed vessel, in which the wort could be stirred up by some arrangement outside. In either case we should have to take care that the air was pure when it came into contact with the wort, but this would be a matter of no difficulty; we would simply have to make communication with the outer air by means of a tube filled with cotton wool. Any air that might be in the vessel at the moment when the wort was introduced would be purified by the high temperature of the wort coming from the copper. We should, moreover, gain the great advantage of being able to bring oxygen to bear on our wort in determinate amounts. From this vessel it would pass on to the refrigerator. We might again raise the wort oxidized on the coolers to a temperature of 75° C. (167° F.), to recool it in this manner and aerate it by means of the pure-air pipe.
Footnote 182:
One of the barrels of the brewery beer was bottled about the end of October, at the same time that a barrel of M was.
Footnote 183:
Refer foot-note, page 354.
Footnote 184:
The evaporation on the coolers varies according to the arrangements in different breweries; but in no case is it less than several hundredths of the total volume. One special advantage of the new process is that it gives us, _ceteris paribus_, a volume of beer that is 5, 6, or 7 per cent. greater than that which we should obtain by the old process, without in any way affecting the strength of the beer. It is easy to ascertain the quantity that evaporates on the coolers, by determining the quantity of water that must be added to a known volume of wort coming from the coolers to bring its density back exactly to that of the original wort, both being calculated to the same temperature. Bate’s English saccharometer, which shows differences of nearly 1/1000th in density, may be employed with advantage in this determination.
APPENDIX.
Whilst this work was passing through the press there appeared two small works on the subject of the generation of inferior organisms.
One of them was by M. Fremy. The author’s object seems to have been merely to give an account, under a new form, of the part which he took in the discussion on the origin of ferments that was carried on before the Academy of Sciences in 1871-1872. In the course of that discussion M. Fremy had announced his intention of publishing an extensive Memoir, full of facts, bearing on the subject. The perusal of the promised work gave us much disappointment. Not only were our experiments, and the conclusions which we drew from them, given there, for the most part in a manner which we could not possibly accept, but, moreover, M. Fremy had confined himself to deducing, by the help of his favourite hypothesis, a series of _à priori_ opinions based on half-finished experiments, not one of which, in our opinion, had been brought to the state of demonstration. To tell the truth, his work was the romance of hemi-organism, just as M. Pouchet’s work of an earlier date was the romance of heterogenesis. And yet, what could be clearer than the subject under discussion? We maintain, adducing incontestable experimental evidence in support of our theory, that living, organized ferments spring only from similar organisms likewise endowed with life; and that the germs of these ferments exist in a state of suspension in the air, or on the exterior surface of objects. M. Fremy asserts that these ferments are formed by the force of hemi-organism acting on albuminous substances, in contact with air. We may put the matter more precisely by two examples:—
Wine is produced by a ferment, that is to say, by minute, vegetative cells which multiply by budding. According to us, the germs of these cells abound in autumn on the surface of grapes and the woody parts of their bunches; and the proofs which we have given of this fact are as clear as any evidence can be. According to M. Fremy, the cells of ferment are produced by spontaneous generation, that is to say, by the transformation of nitrogenous substances contained in the juice of the grape, as soon as that juice is brought into contact with air.
Again, blood flows from a vein; it putrefies, and in a very short time swarms with bacteria or vibrios. According to us the germs of these bacteria and vibrios have been introduced by particles of dust floating in the air or derived from the surface of objects, possibly the body of the wounded animal, or the vessels employed, or a variety of other objects. M. Fremy, on the other hand, asserts that these bacteria or vibrios are produced spontaneously, because the albumen, and the fibrin of the blood themselves possess a semi-organization, which causes them, when in contact with air, to change spontaneously into these marvellously active minute beings.
Has M. Fremy given any proof of the truth of his theory? By no manner of means; he confines himself to asserting that things are as he says they are. He is constantly speaking of hemi-organism and its effects, but we do not find his affirmations supported by a single experimental proof. There is, nevertheless, a very simple means of testing the truth of the theory of hemi-organism; and on this point M. Fremy and ourselves are quite at one. This means consists in taking a quantity of grape juice, blood, wine, &c., from the very interior of the organs which contain those liquids, with the necessary precautions to avoid contact with the
## particles of dust in suspension in the air or spread over objects.
According to the hypothesis of M. Fremy, these liquids must of necessity ferment in the presence of pure air. According to us, the very opposite of this must be the case. Here, then, is a crucial experiment of the most decisive kind for determining the merits of the rival theories, a criterion, moreover, which M. Fremy perfectly admits. In 1863, and again in 1872, we published the earliest experiments that were made in accordance with this decisive method. The result was as follows:—The grape juice did not ferment in vessels full of air, air deprived of its
## particles of dust—that is to say, it did not produce any of the ferments
of wine; the blood did not putrefy—that is to say, it yielded neither bacteria nor vibrios; urine did not become ammoniacal—that is to say, it did not give rise to any organism; in a word the origin of life manifested itself in no single instance.
In the presence of arguments so irresistible as these, M. Fremy, throughout the 250 pages of his work, continues to repeat that these results, which, he admits, seem subversive of his theory, are, nevertheless, explicable by the circumstance that the air in our vessels, although pure at first, underwent a sudden chemical change when it came in contact with the blood, or urine, or grape juice; that the oxygen became converted into carbonic acid gas, and that, in consequence, hemi-organism could no longer exercise its force. We are astonished at this assertion, for M. Fremy must be aware that, since 1863, we have given analyses of the air in our vessels after they had remained sterile for several days—for ten, twenty, thirty, or forty days—at the highest atmospheric temperatures, and that oxygen was still present, often even in proportions almost identical with those to be found in atmospheric air.[185] Why has M. Fremy made no allusion to these analyses? This was the chief, the essential point in question. Besides, if M. Fremy had wished to test the truth of his explanation, there was a very simple means of restoring the purity of the air in contact with the liquids open to him; he might have passed through his vessels a slow and continuous current of pure air, day and night. We have done this a hundred times, and we have always found that the sterility of the putrescible or fermentable liquids remained unaffected.
The hemi-organism hypothesis is, therefore, absolutely untenable, and we have no doubt that our learned friend will eventually declare as much before the Academy, since he has more than once publicly expressed his readiness to do so as soon as our demonstrations appear convincing to him. How can he resist the evidence of such facts and proofs? Persistence in such a course can benefit nobody, but it may depreciate the dignity of science in general esteem. It would gratify us extremely to find the rigorous exactness of our studies on this subject acknowledged by M. Fremy, and regarded by that gentleman with the same favour bestowed upon it everywhere abroad. It may be doubted if there exists at the present day a single person beyond the Rhine who believes in the correctness of Liebig’s theory, of which M. Fremy’s hemi-organism is merely a variation. If M. Fremy still hesitates to accept our demonstrations, the observations of Mr. Tyndall may effect his conversion.
The other publication to which we alluded was the work of the celebrated English physicist, John Tyndall. It was read before the Royal Society of London, at a meeting held on January 13, 1876.
The following letter explains how the illustrious successor of Faraday at the Royal Institution came to undertake these researches:—
“London, February 16, 1876.
“Dear Mr. Pasteur,—
“In the course of the last few years a number of works bearing such titles as ‘The Beginnings of Life’; ‘Evolution and the Origin of Life,’ &c., have been published in England by a young physician, Dr. Bastian. The same author has also published a considerable number of articles in different reviews and journals. The very circumstantial manner in which he describes his experiments, and the tone of assurance with which he advances his conclusions, have produced an immense impression on the English as well as the American public. But what is more serious still, from a practical point of view, is the influence that these writings have exercised on the medical world. He has attacked your works with great vigour, and, although he has made but slight impression on those who know them thoroughly, yet he has succeeded in producing a very great and, I may add, a very pernicious one on others.
“The state of confusion and uncertainty had come to be so great that, about six months ago, I thought that I should be rendering a service to science, and at the same time performing an act of justice to yourself, in submitting the question to a fresh investigation. Putting into execution an idea which I had entertained for some six years, the details of which were set forth in an article in the _British Medical Journal_, which I had the pleasure of sending you, I have gone over a great deal of the ground on which Dr. Bastian had taken his stand, and, I believe, refuted many of the errors by which the public had been misled.
“The change which has taken place since then in the tone of the English medical journals is quite remarkable, and I am inclined to think that the general confidence of the public in the exactness of Dr. Bastian’s experiments has been considerably shaken.
“In taking up these researches again, I have had occasion to refresh my memory by another perusal of your works; they have revived in me all the admiration which I experienced when I first read them. It is my intention now to pursue these researches until I have dissipated any doubts that may be entertained in respect to the unassailable exactness of your conclusions.
“For the first time in the history of science, we are justified in cherishing confidently the hope that, as far as epidemic diseases are concerned, medicine will soon be delivered from empiricism, and placed on a real scientific basis; when that great day shall come, humanity will, in my opinion, recognise the fact that the greatest part of its gratitude will be due to you.
“Believe me, ever very faithfully yours,
“JOHN TYNDALL.”
We need scarcely say that we read this letter with the liveliest gratification, and were delighted to learn that our studies had received the support of one renowned in the scientific world alike for the rigorous accuracy of his experiments as for the lucid and picturesque clearness of all his writings. The reward as well as the ambition of the man of science consists in earning the approbation of his fellow-workers, or that of those whom he esteems as masters.
Mr. Tyndall has observed this remarkable fact, that in a box, the sides of which are coated with glycerine, and the dimensions of which may be variable and of considerable size, all the particles of dust floating in the air inside fall and adhere to the glycerine in the course of a few days. The air in the case is then as pure as that in our double-necked flasks. Moreover, a transmitted ray of light will tell us the moment when this purity is obtained. Mr. Tyndall has proved, in fact, that to an eye rendered sensitive by remaining in darkness for a little, the course of the ray is visible as long as there are any floating particles of dust capable of reflecting or diffusing light, and that, on the other hand, it becomes quite obscure and invisible to the same eye as soon as the air has deposited all its solid particles. When it has done this, which it will do very quickly in two or three days, if we employ one of the boxes used by Mr. Tyndall—it has been proved that any organic infusions whatever may be preserved in the case without undergoing the least putrefactive change, and without producing bacteria.
On the other hand, bacteria will swarm in similar infusions, after an interval of from two to four days, if the vessels which contain them are exposed to the air by which the cases are surrounded. Mr. Tyndall can drop into his boxes, at any time he wishes, some blood from a vein or an artery of an animal, and show conclusively that such blood will not, under these circumstances, undergo any putrefactive change.
Mr. Tyndall concludes his work with a consideration of the probable application of the results given in his paper to the etiology of contagious diseases. We share his views on this subject entirely, and we are obliged to him for having recalled to mind the following statement from our _Studies on the Silkworm Disease_:—“Man has it in his power to cause parasitic diseases to disappear off the surface of the globe, if, as we firmly believe, the doctrine of spontaneous generation is a chimera.”
THE END.
Footnote 185:
See _Comptes rendus_, vol. lxi., p. 734, 1863.
INDEX.
A
Absorption of gases by air-free liquids, 292 oxygen by blood, 50; by urine, 50 from solutions by _bacteria_, 295
Acidity, natural, of wine a preservative, 2, and footnote of beer heated, 20
## action on ferments, 35
Acetate of lime from fermentation of tartrate, 288
Acid, sulphuric, facilitating filtration, 250
Acid, carbonic, _v._ carbonic acid
Adaptability of liquids to certain growths, 36, 73, 85 (supposed) of vibrios to aërobian or anaërobian conditions, 309, 310
Aeration, reviving influence of, 138 adoption by brewers of, 253 tardy, of wort in deep vessels, 348 on “coolers,” its importance, 348, 349
Aeration-conditions in ordinary brewing process, 350, 351, 364, 365
Aeration of wort, apparatus for regulating, 352
Aeration, influence on clarification of worts, 381 experiments on its influence on growth, 107, 130
Aërobian, definition, 116 ferment, growth of, 208, 209 ferments, general characteristics, 210; origin of, 210 (footnote); cultivation of, 211; aspects of, 212-217; distinguishing features of, 218 life in ferments overlooked, 260
“Age,” as applied to a ferment, 169
Age of cells, 246
Aged aspect of exhausted cells, 133, 147
Air, influence on ferment-life, 242 renewal of, in brewers’ yeast, 246, 247 mode of expulsion from growing media, 285 unnecessary to life of _vibrios_, 292 injurious to life of _vibrios_, 304
Air, compressed, and ferment-life, 324 composition unaffected by contact with blood, &c., 398
Albumen-transformation theory of fermentation, 273
Albuminous liquids, growth of yeast in, 265
Alcohol, percentage is heated beer, 20
Alcoholic ferment, minute species of, 71
Alcohol, detection in minute quantity, 78, 79 (footnote) produced by _penicillium_, 99, and following pages by _aspergillus glaucus_, 101, and following pages by _mycoderma vini_, 111, 113 explanation of, 114
Alcoholic fermentation, general explanation of, 114, 115
Alcohol, proportion of, to mucor forming it, 134, and following pages
Alcohol produced by moulds, 258 (footnote) production of, within fruits, 267
Alcoholic fermentation, restricted meaning, 275 (footnote) necessary relation with yeast-cells, 275
_Altenaria tenuis_, 157
Ammonia, a test for vegetable organisms (Robin), 312
Ammoniacal urine, 45, 46
Anaërobian, definition, 116 growth of yeast, 239, and following pages precautions to be observed in, 248 life of fruit-cells, 272 growth of _vibrios_, 302
Animal or vegetable nature of organisms, 312, and following pages
Anti-ferments, 45
Apparatus for sterilizing liquids, 27 for producing pure beer, 340, &c. for pure pitching, 344 for pure aeration, 352 for cooling beer with regulated supply of pure air, 388, 389
Appert’s experiment, 62
Aroma of beer destroyed by excess of air, 353
Asbestos, useful plug, 27, and footnote, 30
Ascospores of yeast, 150 (footnote)
Aspect of yeast variable, 37
_Aspergillus glaucus_, functioning as ferment, 101, and following pages different aspects of, 105
Atmospheric germs, 6, 26, 38 variety of, 39, 76, 87 (footnote)
_Autonomy_ of organisms, 84 (footnote)
B
Bacteria, 35, 36; medium for growth of, 294; absorption of air from solutions by, 295
Bacteria and butyric vibrios, how related, 296 influence of oxygen upon, 305
Bail mentioned, 92, 93, 127
Balling saccharometer explained, 363 (footnote)
Barley-wine, 1 (footnote), 230
Barley decoctions, experiments on development of ferments in, (Fremy) 273 (footnote)
Bary, De, mentioned, 92; on relations of yeast to other organisms, 180, 181
Bastian’s experiments, 403
Baudelot refrigerator, 387 (footnote)
Bavarian beer, 10
Béchamp’s _microzyma_ theory, 121 influence of air on fermentation, 178 (footnote)
Beer, definition, 1; difference between it and wine, 1 changeable nature of: effects upon brewing purposes, 2, 3 two kinds only, “high” and “low:” difference, 7 samples of bottled, examined, 222 general precautions for pure manufacture of, 338 improved apparatus for commercial production, 340, and following pages
Beet root preservation in pits, 269 (footnote)
Berkeley mentioned, 92
Bellamy’s researches on fermentation in fruits, 270
Berard on fermentation of fruits, 270, 271
Berthelot’s mode of isolating inverting constituent of yeast, 322 (footnote)
Bert, action of compressed air on ferments, 324
Birds, experiment upon, described, 309
Bistournage, 43 (footnote)
Bisulphite of lime used by bottlers, 15
Blood, study of sterilized, 49, 50
Blood-crystals, 50 (footnote)
Boiling sterilizes liquids, 34
Bottling needle, 372 (footnote)
Bottled beer, treatment of, 16
_Bouche_ influenced by presence of oxygen, 387
Bouchardat, 323
Brefeld, strictures on Pasteur’s theory criticised, 280 convinced of truth of Pasteur’s theory, 315, 316
Breweries, statistics of, 10
Brewing, change in processes of, 7 practices largely empirical, 222
Brewing processes under conditions of purity, 390
Budding, rate of, experiment on, 145 process of, 146
Buffon’s hypothesis mentioned, 121
Bulbs, glass, for study of growths, 156 (footnote) for vibrios, 298
Bunsen, tables of solubility of oxygen in water, 360
Butyric vibrios in must, 65; in wort, 70
Butyric acid from fermentation of lactates, 297 not a suitable food for vibrios, why?, 301 (footnote)
Butyric fermentations yield variable products, 308
C
Cagniard Latour, on cause of fermentation, 60
Calmettes, M., 369, 371; experiments on the curve of cooling of wort, 377, 378
Carbolic acid for purifying yeasts, 232
Carbonate of lime crystals formed in fermentation of lactate, 294
Carbonic acid, influence on preservation and fermentation of fruits, 268 evolution from fermentation of tartrate of lime by vibrios, 287 amount of evolution, 288 mode of collection of, 288 influence on bacteria, 305 (footnote)
Caseous ferment, occurrence, 200; aspect, 201; endurance of heat, 203 (footnote); meaning of title, 202; origin of in brewers’ high yeast, 203, 204; origin of in English pale ale, 204, 224; aërobian form of, 215
Cells, power of endurance, 134 aspect of dead, 139 (footnote)
Cells, glass, for study of growths, 155 (footnote)
Cells, probable function in elaborating proteic matter, 335
Cellulose, not soluble in ammonia (Robin), 312
Change of yeast, usual remedy for disease, 22
Chauveau on castration, 43
Circumstances modifying nature of germs present in atmosphere, 73, 87 (footnote)
_Cladosporium_, 55 (footnote)
Clarification of liquids by fungi, 66 (footnote) of wort, 381, and following pages of a wort and its beer not always correlated, 382, 383
Cohn’s medium for growth of vibrios, 294 (footnote)
Colour darkened by oxidation in pure liquids, 57
Coloration of vibrio-fermented liquors, 291
Colpoda, 39, 40
Composition of medium, influence on life, 296
Conidia, definition, 137
Conditions affecting the ferment character of cells, 266
Consumption of beer in France, statistics, 17 (footnote)
Contagion and ferments, 41, and following pages
Continuity, non-, of germs in air, 62
Continuous vital activity of cells, 278
Contact-action, theory of, 326
“Coolers,” importance in aeration of wort, 348, 349 influence on worts, 364
Cooling of wort must be rapid in ordinary brewing, 2 artificial of “low” beers, 12
Cooling of wort in presence of carbonic acid, 342; difficulties of the process, 346, and following pages
Corpuscles on grapes and stalks, 54
Corpuscles refractive in bodies of vibrios, 300, _v._ also cysts
Correlation of special germs with special fruits, 61 of special ferment and fermentation product, 277
Cotze and Feltz, 43
Crushers for the vintage, 268 (footnote)
Cream of tartar, _v._ tartrate
Cultivation of yeast under conditions of purity, 29-32 of pure penicillium, mode of, 88, and following pages of aërobian ferments, 211, and following pages
Cysts of vibrios, 306, 307
D
Davainne, on splenic fever, &c., 42
Daughter-cells, 146
Dead cells, aspect of, 139 (footnote)
Declat’s treatment of infectious diseases, 44
_Dematium_, 167; resemblance to _Saccharomyces pastorianus_, 179, 180, 181, 214 resemblance to “caseous” yeast, 201
Degrees, Balling, _v._ Balling
Deposits, amorphous, of wort, 6, 193, 385, and footnote
Deterioration of beer correlated with presence of foreign organisms, 26, 32
Differential vitality, a means of separating ferments, 226
Difficulty of experiments on growths, 63, 85
Disease-ferments, what they are, why so called, 4 classification and account of, 5, 6 origin of, 6 inactive at low temperatures, 14 often found only in deposits, 24 not everywhere in atmosphere, 31
Disease-germs usually latent, 220 development in bottled beer, 222
Diseases of wort and beer, meaning of, 19 mode of proving the cause of, 19, 20
Diseased beer always result of disease ferments, 26
Distribution of germs limited, 61
Division, fissiparous, of vibrios, 299
Dried yeast, 81
Dryness decreases sensitiveness of moulds to heat, 35
Dumas, distinction between organized and unorganized ferments, 323
Dust, atmospheric, contains disease-germs, 6, 26 on fruits, experiments with, 153, and following pages when fertile, 157, and following pages
Dutch yeast, 200
Duval, Jules, experiments on transformation of ferments illusory, 37
E
_Efflorescence_ of fermented liquors, 108, 117
Egg-albumen, experiments on, 51
Egypt, beer first brewed in, 17
Empiricism in ordinary brewing, 222
Energy stored by cells, 133, 134
Endogenous sporulation of yeast, 150 (footnote), 172
English beers all “high,” 7 temperatures and yeast employed, 8 (footnote) breweries, usages of, 8 (footnote), 14
Errors, causes of, _v._ experimental errors
Equations of fermentations variable, 276, 277
Examination of deposits, mode of, 21 (footnote)
Exhaustion, definition of, 171 (footnote)
Exhausted vibrios, 290
Experimental errors, 63, 85, 92 avoided by use of double-necked flasks, 120
Experiments, exactness of Pasteur’s, 95 (footnote) to prove connection between quality of ferment and quality of beer, 26, and following pages on living fluids, 47, and following pages comparative, on pure must and must with corpuscles boiled and unboiled, 54, and following pages by Gay-Lussac on must, 62, 63 by Pasteur after Gay-Lussac, 64 on distribution of ferments, 65, and following pages on distribution of fungus-spores, 68 in wide shallow dishes, 69, and following pages comparative on germs in air, 72, and following pages with non-fermentative species of _torula_, 78 on spontaneous impregnations, 65, 66, 69, 73, 79, 87 (footnote) on spontaneous fermentation, 184 on dried yeast, 81, and following pages on influence of aeration on growths, 107 on aeration and its absence, 130, and following pages on function of oxygen on ferment-life, 238, and following pages on the capacity of yeast for oxygen, 255 on influence of carbonic acid on fruits, 268 on growth of vibrios apart from air, 285 on fermentation of lactate of lime apart from air, 292, and following pages on influence of air on vibrio-life, 303, 304 on influence of air on bacterium-life, 305 on gradual adaptability of organisms to adverse life-conditions, 309 on influence of air on fermentation, 349 on solubility-coefficients of wort for oxygen, 361-3 of brewers’ worts, 366, and following pages on combination of oxygen with worts, 371, and following pages on the rapidity of the combination, 376 on amount of combination, 379 on non-transformation of _mycoderma vini_, 110, and following pages, 113 (footnote) of _mycoderma aceti_, 124, and following pages of _mucor racemosus_, 128, and following pages on non-transformation of yeast into penicillium, 333-335 on cultivating pure _penicillium_, 88, and following pages on its transformation into yeast, 91 transformation, Trécul’s, details of, 98 with submerged _aspergillus_, 101, and following pages _penicillium_, 99 in disproof of the _hemi-organism_ theory, 273 (footnote) on growth of mixed moulds, 112 on purification of mixed ferments, 226, and following pages on growth of _mucor mucedo_, 140, 141 on proportion between weights of mucor and alcohol formed, 134, and following pages on the anaërobian cultivation of yeast, 239, and following pages on variation of proportion of sugar used to yeast formed, 249 on growth of yeast in sugar solutions, 318, and following pages, 331-333 on dust on fruits, 153, and following pages on seasonal influences on fertility of dust-germs, 157, and following pages on exhaustion of yeast, 169, and following pages of “high” yeast, 189, 190 on revival of yeast, 207, 208 on cultivation of aërobian ferment, 211, and following pages on gradual _senescence_ of yeast, 245 on production of a pure beer, 338, and following pages on clarification of worts and beers, 382, and following pages comparative, on the qualities of beers brewed by different processes, 391 on rate of budding, 145
Exportation of “high” beers unsatisfactory, 16
F
Ferment, _v._ also yeast
Ferments of disease, _v._ disease-ferments
Ferments, special, 14, 15
Ferments and animal diseases, 41, and following pages butyric, lactic, alcoholic, 72 moulds functioning as, 100, 101, and following pages, 111, 113, 129, 133 general character of a, 115 of grape, varieties, origin, 150, and following pages alcoholic, summary of, 196 intermixture of, 224, 225 mode of separation of mixed, 226 and following pages succession of, in must, 227 exceptional vital processes of, 236, 237
Ferment power in relation to time discussed, 252 character, how related to heat, 270 and fermentation correlated, 277 a chemical substance existing in cells (Traube), 283 (footnote) of tartrate of lime, 290
Ferments, two classes, distinctive characteristics, 323
Fermentation, rapid, inexpedient, 3 spontaneous, in case of must, 4 “top” and “bottom,” _v._ “high” and “low” masked by moulds in shallow vessels, 75 (footnote) by _penicillium_ (Tréoul) 94 by _mycoderma vini_, 111, 113 by _mucor racemosus_, 129, 139 alcoholic, general explanation of, 114, 115 conditions of, in sweetened mineral liquids, 211 without air, 242 with and without air, results compared, 243, 244 a cell-life without air, 259 a general phenomenon, 266, 267 of fruits not truly “alcoholic,” 276 not definable, according to Brefeld, as life without air, 280 of lactate of lime, 294
Fermentative energy, 252 character dependent on conditions, 266
Filamentous tissue (Turpin), 123
Fitz on fermentation, 142
Fissiparous division of vibrios, 299
Flask sterilizing, 27, 29
Flasks with double necks, advantage of, 120
Fluid, Raulin’s, 88 (footnote)
Flavour dependent on ferment species, 230
Foreign organisms correlated with unsound beer, 26, 32 greatly promoted by adaptability of liquids, 36
Formula for solubility-coefficient of any wort for oxygen, 364
Fremy’s statement of _hemi-organism_, 52 answer to Pasteur’s facts, 58 explanation of vintage fermentation, 272 “organic impulse,” 325 latest assertions, 396-399
Fruits, ferment organisms on surface of, 153, and following pages internal fermentation of, 267, and following pages yeast cells not present within, 267 (footnote) influence of carbonic acid gas on preservation of, 268 respiratory processes of, according to Bérard, 270 fermentation within, Lechartier and Bellamy, 270 crushed and uncrushed, fermentation of, 274
Fruit-cells, anaërobian life of, 272
Fungi, wide distribution of spores, 68 absorption of oxygen by, 257 production of alcohol by, 258 (footnote)
Fungoid manner of growth of well-aerated yeast, 251
G
Galland’s claims of priority, 338 (footnote)
Gay-Lussac’s experiments on grape-juice, 59, 60
Gayon’s experiments on egg-albumen, 51
“Gathered,” 367 (footnote)
Generation, theories of, contrasted, 397
Germs of ferments in air, &c., 6, 26, 38 brought by other matters, 38 absent from fruits, when? 58, 59, 157, and following pages not universally distributed, 61, 63, 181 (footnote) distribution experiments, 65, and following pages, 87 (footnote) and their correlated fruits, 61 of disease latent, 220
_Germ_, use of term by Pasteur, 313
Germ theory of disease discussed, 46, 47
Globuline tissue (Turpin), 123
Globulines, punctiform, 121, and following pages
Globules, 275 (footnote)
Glycerine, fermentation of, by vibrios, 306, 307
Gosselin, M., report, 44 and Robin on ammoniacal urine, 45
Gramme, value in grains, 135 (footnote)
Granules in wort, explanation of, 95
Graham’s, Dr., criticisms of Pasteur, 13 (footnote), 196 (footnote)
Graham, Dr., on aspect of bottom yeast, 194 (footnote)
Grape juice, experiments on, 57, 59
Grape-ferments, _v._ ferments
Grapes, do they contain cells of yeast? 267
Greasiness of _mycoderma vini_, 80, and footnote
H
Hallier mentioned, 92
Hard water, influence on aspect of yeast, 194 (footnote)
_Head_ of vibrio, 292
Heating sufficient as preventing deterioration of liquids, 20 influence on beer, 20
Heat, production of, its relation to ferment-power, 270
_Hemi-organism_, chimerical, 53, 162, 399, 273 (footnote) latest assertions by Fremy on subject of, 396-399 theory of vintage-fermentation, 272, 273
Heterogenesis, facts against, 51
“High” fermentation, meaning of, 8, 9 beers, disadvantages of, 12, 13 ferment, aspect of, 188, 189 characteristics of, summary, 191 ferment (new), occurrence, 198 aspect and characteristics of, 199 aërobian form of, 216
High yeast, aërobian form, aspect of, 214
Hoffmann, H., transformation of ferment, 92, 93
Hop-oil as a beer-antiseptic, 16, and footnote
Hopping influence on growths _quâ_ temperature, 96
Hot countries, absence of breweries in 16
Hydrogen from vibrionic life, 300 occasional absence in butyric fermentations, 308
Hydrosulphite of soda, composition, use in determinations of oxygen, 355, and footnote preparation of _saturated_ solution, 357 (footnote) alterability of solutions of, 356 improved method of M. Raulin, 356, and following pages
I
Ice, quantities consumed in “low” breweries, 11
Illusions as to absence of foreign organisms, 36, 85, 92
Impregnations, spontaneous, 65, 66, 69, 73, 79
Impregnation, mode of (_penicillium glaucum_), 86
Impurity of ferments, source of experimental errors, 37 of yeast masked for a time, 220
Increase of yeast disproportionate to sugar used, 237
Infusions, nature of organisms in, 39
Infusoria, 35
Insoluble substances in wort, 386
Inverting constituent of yeast, 321, and footnote
Isolation of ferment, 77
L
Lactic ferments, 5, 36 transformation from and into other ferments (Duval), 37
Lactate of lime, fermentation of, 292
Lechartier and Bellamy, researches on fermentation in fruits, 270
Leptothrix, 36
Liebig’s views of fermentation, 317, and following pages on fermentation of malate of lime, 321 definition of a ferment, 324 modified theory, 326; answer to, by Pasteur, 326, 327 neglect of microscopical observations, 329, 330
Lime, bisulphite, use of, by bottlers, 15 carbonate sterilized, use of in growths, 126 dextro-tartrate, 284 acetate and metacetate, 288 lactate, fermentation of, 292
Lister’s, Prof., letter on germ-theory, 43
London breweries, usages of, 8 (footnote) Pasteur’s visit to, 22-24
“Low” fermentation, meaning of, 9, 10; advantages, 12 beer breweries, statistics of, 10 properties of, according to Dr. Graham, 13 yeast and “high” yeast distinct, 192, 193 yeast, aspect of, 193; characteristics, 195 aërobian form of, 215
Low temperatures prejudicial to disease-ferments, 14
M
Malignant pustule, 42
Mashings, 3
Medium, mineral, for growing lactic vibrios, 293, 297 (footnote) Cohn’s formula, 294 (footnote) for growth of bacteria, 294
Medium, composition of, influence on life, 296
Microscopical study of yeast important, 23 formerly neglected in English breweries, 22-24
Microscopical examination of vibrios, 298, 299
Microzyma, 121; source of _mycoderma aceti_ according to Béchamp, 124
Milk, temperature of sterilization of, 34
Milk-sugar, growth of yeast in, 265
_Mother of vinegar_, _v._ mycoderma aceti
Moulds thrive in acid liquors, 36 functioning as ferments, 100, 101, and following pages, 111, 113, 129, 133 growth of, and production of alcohol, 257, 258 (footnote) suggested employment of, industrially, 261
Mucedines, 36, 40
_Mucor mucedo_ and _racemosus_ on must, 66
_Mucor racemosus_, different aspects of, 105 pure growth of, 128, and following pages
Mucor normal, growth of, 132 weight of to alcohol formed, 134, and following pages morphology of abnormal growth, 137
_Mucor mucedo_ distinguished from _racemosus_, 140 growth in double-necked flasks, 140, 141
Müntz, 323
Must, fermentation of, always regular, 3 pure fermentation of, 54, and following pages succession of ferments in, 227, 228
_Mycelium_ and _mycoderma vini_ on wine, 56, 65
Mycoderma in wort experiments, 70
_Mycoderma vini_, arborescent form of, 77 growth of pure, experiments on, 110, and following pages, 120 growth with _penicillium_, 112 with _mucor_, 112 endogenous sporulation, 151 (footnote)
_Mycoderma aceti_ transformations (Béchamp), 124 pure growth of, 124, and following pages
N
_Nageurs_ used in low fermentation, 9
Nature of liquids, influence on growths, 36, 73, 85
Natural liquids for pure growths, use of, 40, 41 experiments on, 47, and following pages
Neutrality, conditions of, as affecting sterilization of liquids, 34; explanation of fact, 35
Neutralization of acidity in pure growths, mode of, 126
New high ferment, _v._ high
New process of brewing, 391-393
Nitrogenous soluble parts of yeast, 319, 320
Nomenclature used by Pasteur purposely vague, 314
Normal growth of mucor, 132
O
Organic substances, have they any tendency to become organized? 33
Organic liquids sterilized by boiling, 34
Organizable globulines (Turpin), 123
Organisms and animal diseases, 42
_Ouillage_, 2
Oxidation of germ-free liquids, 57 processes of fungi, 261, and footnote of wort, excessive, injurious, 353, 354
Oxygen absorbed by blood, 50 by urine, 50 and fermentation, according to Gay-Lussac, 60 store-energy imparted to cells by, 134 no influence upon fermentation, (Béchamp), 178 (footnote) function in fermentation, experiments on, 238, and following pages influence on fermentation (Schützenberger and Pasteur), 253, 254 amount absorbable by yeast, 255 deficiency of, function in fermentation, 259 influence on products, 100, 108, 113 influence on morphology of moulds and ferments, 105, 106, 133, 137, 262 necessity of, to growth of yeast discussed, 280 unnecessary and adverse to vibrionic life, 284, and following pages necessary to bacterial life, 305 removal from solutions by bacteria, 295 growth of vibrios apart from, 302 compressed, influence on ferment life, 324 determination of, in worts (Schützenberger), 355, and following pages solubility-coefficients in water (Bunsen), 360 usual amounts in solution in brewers’ worts, 366, 367 changes in amounts during brewing processes, 369, 370 combination of, with hopped wort, 371, and following pages experiments on rapidity of combination, 376 on amount of, under brewing conditions, 379 in combination with wort not available for yeast, 380, 381 clarification of wort by, 385
P
Palate-fulness definition, 354, and footnote impaired by oxidation, 354
Parasites and their germs, 40 influence on animal diseases, 41
Pasteur’s repetition of Trécul’s experiments, 98, 99 subject of his inquiries stated, 311 experiments, exactness of, 95 (footnote)
Pasteurization, meaning and use, 15 (footnote)
Patches of froth in growth of pure yeast, 31
_Penicillium glaucum_ on must, 66 growth of pure, 86, and following pages precaution, 89 transformed into ferment (Trécul), 94 spores, varieties of, 97 production of alcohol by, 99, and following pages transformation into mycoderma, 109
Phenol for purifying yeasts, 232
Pitching, mode of, for pure beer, 342, and following pages flasks, 344 peculiar in London breweries, explanation, 350, 351
Plaster of Paris and yeast powder, 81, and following pages
_Ploussard_ grapes, experiments on, 161
Polymorphism of organisms, 84 (footnote), also _v._ transformation
Precautions for pure fermentation of must, 64 brewers’, to check disease-germs, 220, and following pages for pure anaërobian growth of yeast, 248
Preservation of yeast, 207
Preoccupation of liquids by organisms, 36, 109, 220
Products of fermentation variable, 276, 277
Price of beer as affected by losses from disease, 24
Proliferous pellicles, 121
Proportions of alcoholic products variable, 276, 277
Proportions of products diagnostic of the fermentation, 279
Proteic matter elaborated by cells, 335
“Pulling up,” 343
Pure growth of yeast, precautions for, 29-32 growths in natural liquids, 40, 41 wort and ferment, advantages of, 391-393
Purification of mixed ferments, 226, and following pages practical methods, growth in sweetened water, 230 shallow basins, 231 in acid and alcoholic liquids, 231 with aid of carbolic acid, 232
Putrid wort, ferments of, 5
Putrefaction prevented by use of sterilizing flask, 27 of yeast, cause of, 221 of tartrate of lime, 291
Q
Qualities of “high” and “low” beers, 12, 13, 19, 196
Quality of beer dependent on kind of ferment, 26, and following pages
R
Racking, 222 precautions necessary in, 351
Raulin’s fluid, 88 (footnote) improvement on Schützenberger’s oxygen process, 356, and following pages experiments on solubility of oxygen in worts, 361-363
Rayer on splenic fever, &c., 42
Reducing action of vibrios, 291
Rees, Dr., 150 (footnote)
Refrigerator, Baudelot’s, 387 (footnote)
Revival of mould-cells by aeration, 130, 131 (footnote), 138
Revival of starved yeast, 148, 208 vibrios, 301, 302
Ripening of fruits, 270, 271
Robin, Ch., mentioned, 93; strictures on Pasteur, 310, 311 recantation of views on fermentation, 314
S
_Saccharomyces apiculatus_, 71, and footnote, 150 _exiguus_, 185, _ellipsoideus_, 165 _pastorianus_ 151; mode of growth of, 167 two aspects, globular and filamentous, 168, 169 exhaustion and revival of, aspects, 172, and following pages occurrence as impurity in most ferments, 225 most suitable for growth experiments in sugar solutions, 332
_Saccharomyces pastorianus_, _ellipsoideus_, _apiculatus_ in must, 227, and following pages
_Sang de rate_, 43
Schützenberger on budding of yeast, 146, and footnote
Schützenberger’s strictures on Pasteur’s views answered, 252, and following pages process for determining oxygen in solutions, 355
Seasons, influence on success in brewing, 25 at which germs are absent on fruits, 58, 59
Secondary fermentation in English beers, 224
_Senescence_ of yeast cells, 208 gradual of yeast cells, experiments on, 245
Shallow basins for purification of yeasts, 231
Sodium hydrosulphite, _v._ hydrosulphite
Solubility-coefficients of oxygen in water (Bunsen), 360 in worts (Raulin), 361-363
Sour beer, ferments of, 5
Soundness of beer always dependent on purity of yeast, 26, 32
Specialization of ferment-variations, 197
Specimens, necessary precautions for taking, 126 (footnote)
Splenic fever, 42
Spontaneous fermentation used in must, not in beer, 4 fermentation or putrefaction prevented by use of sterilizing flask, 28 ferment, definition of, 182; experiment on, 184 generation, facts against, 51, 52, 57 supported by experimental errors, 62, 63 (Trécul’s theory of), 94, 95 impregnations, 65, 66, 69, 73, 79 use in isolating ferments, 77
Spores on grapes, gooseberries, &c., 54 of fungi widely distributed, 68
Statistics of breweries, 10 of French beer consumption, 17 (footnote)
Starved yeast, appearance of, 148
Stability of sterilized liquids, 286
_Stemphylium_ spores, 55 (footnote)
Sterilizing apparatus, 27, 29, 285 flask, 28
Sterilization-temperature of various liquids, 34
Stock beer, 223
Store beer, must be surrounded by ice, 16
Straw wine, peculiar fermentation of, 166
_Strength_, Pasteur’s use of word, 354 saving by the new process, 394
Submerged _penicillium_, 99 _aspergillus_, 101, and following pages _mycoderma_, 111, 113, and following pages _mucor_, 129, and following pages, 133
Submerging growths, precautions for, 91 (footnote)
Succession of transformations (Trécul’s scheme), 93, 94
Sugar decomposition by submerged cells, 114 different modes of, by different cells, 115 decomposed disproportionate to yeast formed, 237, and following pages variation of disproportion in different cases, 249 amount decomposed in a given time, as an index of fermentative energy (Schützenberger’s views), 252 solutions pure with mineral salts, growth of yeast in, 317, and following pages denial of the fact by Liebig and reply by Pasteur, 328, 329
Surface growth of yeast in pure culture, 31
Sweetened water for exhausting yeast, 169, 170, 190 for purification of yeasts, 230
T
Tartrate-acid of potash for purifying yeasts, 231 -dextro of lime, fermentation of, 284, and following pages products of, 288 ferment of, 290
Temperatures in use in London breweries, 8 (footnote) high, prejudicial to quality of “low” beer, 19 at which disease-ferments perish, 20; differs in different liquids, 34, 96 influence on fermentation, 129
Temperatures suitable for “high” or “low” yeasts respectively, 192 influence of on mixed “high” and “caseous” yeasts, 203 for observing active vibrios, 299
Theories of generation opposite stated, 397
Tieghem, Van, on ammoniacal urine, 45
Torula, sense in which used, 73 (footnote) varieties of, 77 non-fermentative species, 78
Transformation of ferments, according to Duval, 37 of non-fermentative to fermentative impracticable, 80 of _penicillium_ into yeast impracticable, 91 of ferment into moulds (Hoffmann), 92 series, Trécul’s scheme of, 93, 94 of _penicillium_ to _mycoderma_ (Ch. Robin), 109 (footnote) of _mycoderma vini_ refuted, 113 (footnote) Turpin’s system of, 122, and following pages of _mycoderma aceti_ (Béchamp), 124 historical account of views on, 128 (footnote) of _mucor_ (Bail), 127 of filamentous into globular yeast, 169 of yeast into _penicillium_, &c., impracticable, 333-335 mutual of low and high yeast, discussed, 192, 193 of “high” yeast into “caseous” ferment illusory, 203 of albumen, theory of the vintage, 272, 273 theory disproved generally, 273 (footnote)
Traube, Dr., on ammoniacal urine, 46 researches on fermentation, 282 theory of fermentation, 283 (footnote)
Trécul and Fremy, _v._ Fremy
Trécul’s theory of successive transformations, 93, 94 details of transformation experiments, 98 theory refuted, 99
_Trousseau_ grapes, experiments on, 162
“Turned” beer, ferments of, 5; filaments of, 23
“Turning out,” 367 (footnote)
Turpin, M., mentioned, 92
Turpin’s system of transformations, 122, and following pages, 113 (footnote)
Tyndall, letter to Pasteur, 399-401
U
Unsoundness of beer correlated with disease-organisms, 26, 32
Urea-ferment, the transformation of (Duval), 37
Urine, ammoniacal, 45, 46
Urine, sterilized, study of, 49, 50
V
Variability of fermentation products, 277
Variations of ferment strengthened and established, 197
Varieties of yeast, 149, and following pages
Vaureal, De, budding of yeast, 146 (footnote)
Vegetable distinguished from animal organisms by ammonia (Robin), 312
Vesicular tissue (Turpin), 123
Vibrio, 36; butyric, 65, 70 also an example of anäerobian life, 282, 284
## active and exhausted, 290
reducing action of, 291
Vibrionic ferment of tartrate of lime, 290
Vibrios, _head_ of, 292; supposed reproductive corpuscles, 306 growth of, in lactate media, 293 medium for growth of, according to Cohn, 294 (footnote) not genetically related to bacteria, 296 of butyric fermentation, description of, 298, 300 mode of examining microscopically, 298 fissiparous division of, 299 measurements of, 300 cannot live on butyrates, 301 (footnote) revival of, 301, 302; anaërobian growth of, 302 life of, destroyed by oxygen, 303, 304
Vigour of ordinary brewer’s yeast, 246
_Vin de paille_, 166
Vinegar, temperature at which it is sterilized, 34
Vinous flavour in stock beer, 224
Vintage, varied conditions of, 268 (footnote) fermentation, theory of, according to Fremy, 272, and following pages
Viscous wort, ferments of, 5
Visit to London brewery by Pasteur, 22-24
Vital processes of ferment exceptional, 237
## activity of yeast apart from air, 259
potential in cells, 278
Vitiation of experiments, causes of, 63, 85, 92
W
Wad-dressing, antiseptic, 44
Water, hard, influence on aspect of yeast, 194 (footnote)
Weights of _mucor_ and alcohol, proportion of, 134, and following pages
Weight of yeast grown, what due to, 257 (footnote)
Wide dishes, experiments on fermentation in, 69, 70 favourable to mould developments, 75 (footnote)
Wine, less liable to deteriorate than beer, 2 temperature of sterilization, 34
Wort, definition, 2; cooling of, 3, 4 temperature of sterilization, 34 solubility of oxygen in, 361, and following pages formula for solubility in any wort, 364
Worts, brewers’, usual amounts of oxygen in solution, 366, 367 experiments on amounts, 379
Wort, hopped, its affinity for oxygen, 371, and following pages mode of transmitting it free of oxygen, 371, 372 insoluble substances in, 386
Y
Yeast, _v._ also ferment, germs, torulæ nature and properties of, 143, and following pages starved and well-nourished, appearances contrasted, 147, 148 varieties of, 149, and following pages commercial origin of, where? 187 relations to other organisms, 180, 181 commercial mixtures, 224, 225 practical purification of, 230-233 impurities in masked for a time, 220 exceptional characteristics of, 237 growth of in sterilizing flasks, 29-32 not transformable into any other organism, 37 aspect may change under modified circumstances, 37 non-transformation of _mycoderma vini_ into, 120 _mucor_ into, 132 non-fermentative species of, 79, 80, 206, 207 “high,” characteristic aspect of, 188-192 well aerated, fungoid mode of growth, 251 anaërobian growth, cause of fermentation, 259 growth of, in solutions of sugar, 318, and following pages growth in relation to proportion of sugar used, 237, and following pages difficult propagation in saccharine mineral media, 329, 330 growth of, without producing alcohol, 265 capacity of absorbing oxygen, 255 necessity of oxygen for its growth discussed, 280 incapable of using oxygen in combination in worts, 380, 381 soluble nitrogenous part of, 320, 321, 79 (footnote) dried into dust still active, 81, and following pages does not perish at temperatures at which disease-ferments do, 20 sudden inactivity of, cause and cure, 347 (footnote) change of, a trade custom, 22 reason of addition of yeast to wort, 3 proportion commonly added, 3 reason of the large proportion used, 343.
Yeast-cells abundant in brewing laboratories, 75 gradual senescence of, 245
Yeast-cells, mode of examining fruits for, 267 (footnote) necessary relation to “alcoholic fermentation,” 275
Yeast-water, definition, 79 (footnote) exhaustion of yeast by, 171 use of in pure growths (_penicillium_), 88
“Youth” of cells, 246
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● Transcriber’s Notes: ○ Missing or obscured punctuation was silently corrected. ○ Inconsistent spelling and hyphenation were made consistent only when a predominant form was found in this book. ○ Text that was in italics is enclosed by underscores (_italics_). ○ Text that was in bold face is enclosed by equals signs (=bold=). ○ Footnotes have been moved to follow the chapters in which they are referenced. ○ Subscripts are transcribed by an underscore and a value enclosed in braces, such as O_{2}. Superscripts are transcribed by an up-caret and a value enclosed in braces, such as MC^2, or sometimes by an up-caret and a single character, such as 4^e.
End of Project Gutenberg's Studies on Fermentation, by Louis Pasteur