,,transcriber',s ,,note4 ,original spelling and grammar are mostly retained4 ,text enclosed by _/solidus characters_/ was in italics4 ,text that was originally in bold or in small caps is capitalized4 ,the phrase a means that a is subscripted1 as in ,h#b,o4 ,the phrase ab means that the phrase ab is superscripted4 ,this book contains several uncommon ,unicode characters1 including 1 1 1 1 1 1 4 ,a monospace font capable of rendering these is necessary for reading this book4 ,further details are provided in the ,transcriber's ,endnote4 ,,alcoholic ,,fermentation #b,,nd ,,edition1 #aiad4 ,by ,,arthur ,,harden4 ,,monographs ,,on ,,biochemistry ,,edited ,,by ,r4 ,h4 ,a4 ,,plimmer1 ,d4,sc4 ,,and ,f4 ,g4 ,,hopkins1 ,m4,a41 ,m4,b41 ,d4,sc41 ,f4,r4,s4 ,,general ,,preface4 ,the subject of ,physiological ,chemistry1 or ,biochemistry1 is enlarging its borders to such an extent at the present time that no single text-book upon the subject1 without being cumbrous1 can adequately deal with it as a whole1 so as to give both a general and a detailed account of its present position4 ,it is1 moreover1 difficult1 in the case of the larger text-books1 to keep abreast of so rapidly growing a science by means of new editions1 and such volumes are therefore issued when much of their contents has become obsolete4 ,for this reason1 an attempt is being made to place this branch of science in a more accessible position by issuing a series of monographs upon the various chapters of the subject1 each independent of and yet dependent upon the others1 so that from time to time1 as new material and the demand therefor necessitate1 a new edition of each monograph can be issued without reissuing the whole series4 ,in this way1 both the expenses of publication and the expense to the purchaser will be diminished1 and by a moderate outlay it will be possible to obtain a full account of any particular subject as nearly current as possible4 ,the editors of these monographs have kept two objects in view3 firstly1 that each author should be himself working at the subject with which he deals2 and1 secondly1 that a _/,bibliography_/1 as complete as possible1 should be included1 in order to avoid cross references1 which are apt to be wrongly cited1 and in order that each monograph may yield full and independent information of the work which has been done upon the subject4 ,it has been decided as a general scheme that the volumes first issued shall deal with the pure chemistry of physiological products and with certain general aspects of the subject4 ,subsequent monographs will be devoted to such questions as the chemistry of special tissues and particular aspects of metabolism4 ,so the series1 if continued1 will proceed from physiological chemistry to what may be now more properly termed chemical physiology4 ,this will depend upon the success which the first series achieves1 and upon the divisions of the subject which may be of interest at the time4 ,r4 ,h4 ,a4 ,p4 ,f4 ,g4 ,h4 ,,monographs ,,on ,,biochemistry ,,royal #hvo4 ,,the ,,nature ,,of ,,enzyme ,,action4 ,by ,w4 ,m4 ,,bayliss1 ,d4,sc41 ,f4,r4,s4 ,third ,edition4 #es4 net4 ,,the ,,chemical ,,constitution ,,of ,,the ,,proteins4 ,by ,r4 ,h4 ,a4 ,,plimmer1 ,d4,sc4 ,part ,i4--,analysis4 ,second ,edition1 ,revised and ,enlarged4 #es4 #f;d4 net4 ,part ,,ii4--,synthesis1 etc4 ,second ,edition1 ,revised and ,enlarged4 #cs4 #f;d4 net4 ,,the ,,general ,,characters ,,of ,,the ,,proteins4 ,by ,s4 ,b4 ,,schryver1 ,ph4,d41 ,d4,sc4 #bs4 #f;d4 net4 ,,the ,,vegetable ,,proteins4 ,by ,,thomas ,b4 ,,osborne1 ,ph4,d4 #cs4 #f;d4 net4 ,,the ,,simple ,,carbohydrates ,,and ,,the ,,glucosides4 ,by ,e4 ,,frankland ,,armstrong1 ,d4,sc41 ,ph4,d4 ,second ,edition1 ,revised and ,enlarged4 #es4 net4 ,,the ,,fats4 ,by ,j4 ,b4 ,,leathes1 ,f4,r4,s41 ,m4,a41 ,m4,b41 ,f4,r4,c4,s4 #ds4 net4 ,,alcoholic ,,fermentation4 ,by ,a4 ,,harden1 ,ph4,d41 ,d4,sc41 ,f4,r4,s4 ,second ,edition4 #ds4 net4 ,,the ,,physiology ,,of ,,protein ,,metabolism4 ,by ,e4 ,p4 ,,cathcart1 ,m4,d41 ,d4,sc4 #ds4 #f;d4 net4 ,,soil ,,conditions ,,and ,,plant ,,growth4 ,by ,e4 ,j4 ,,russell1 ,d4,sc4 #es4 net4 ,,oxidations ,,and ,,reductions ,,in ,,the ,,animal ,,body4 ,by ,h4 ,d4 ,,dakin1 ,d4,sc41 ,f4,i4,c4 #ds4 net4 ,,the ,,simpler ,,natural ,,bases4 ,by ,g4 ,,barger1 ,m4,a41 ,d4,sc4 #fs4 net4 ,,nucleic ,,acids4 ,,their ,,chemical ,,properties ,,and ,,physiological ,,conduct4 ,by ,,walter ,,jones1 ,ph4,d4 #cs4 #f;d4 net4 ,,the ,,development ,,and ,,present ,,position ,,of ,,biological ,,chemistry4 ,by ,f4 ,,gowland ,,hopkins1 ,m4,a41 ,m4,b41 ,d4,sc41 ,f4,r4,s4 ,,the ,,polysaccharides4 ,by ,,arthur ,r4 ,,ling1 ,f4,i4,c4 ,,colloids4 ,by ,w4 ,b4 ,,hardy1 ,m4,a41 ,f4,r4,s4 ,,respiratory ,,exchange ,,in ,,animals4 ,by ,a4 ,,krogh1 ,ph4,d4 ,,protamines ,,and ,,histones4 ,by ,a4 ,,kossel1 ,ph4,d4 ,,lecithin ,,and ,,allied ,,substances4 ,by ,h4 ,,maclean1 ,m4,d41 ,d4,sc4 ,,the ,,ornamental ,,plant ,,pigments4 ,by ,a4 ,g4 ,,perkin1 ,f4,r4,s4 ,,chlorophyll ,,and ,,haemoglobin4 ,by4 ,h4 ,j4 ,,page1 ,b4,sc4 ,,organic ,,compounds ,,of ,,arsenic ,,and ,,antimony4 ,by ,,gilbert ,t4 ,,morgan1 ,d4,sc41 ,f4,i4,c4 ,,longmans1 ,,green ,,and ,,co41 ,,london1 ,,new ,,york1 ,,bombay1 ,,calcutta1 ,,and ,,madras4 ,,alcoholic ,,fermentation ,,by ,,arthur ,,harden1 ,,ph4,d41 ,d4,,sc41 ,f4,r4,s4 ,,professor ,,of ,,biochemistry1 ,,london ,,university ,,head ,,of ,,the ,,biochemical ,,department1 ,,lister ,,institute1 ,,chelsea ,illustration3 sailing ship in crown-like frame _/,,second ,,edition_/ ,,longmans1 ,,green ,,and ,,co4 #ci ,,paternoster ,,row1 ,,london ,,fourth ,,avenue #cj,,th ,,street1 ,,new ,,york ,,bombay1 ,,calcutta1 ,,and ,,madras #aiad ,,preface4 ,the following chapters are based on courses of lectures delivered at the ,london ,university and the ,royal ,institution during #aiji-aiaj4 ,in them an account is given of the work done on alcoholic fermentation since ,buchner's epoch-making discovery of zymase1 only in so far as it appears to throw light on the nature of that phenomenon4 ,many interesting subjects1 therefore1 have perforce been left untouched1 among them the problem of the formation of zymase in the cell1 and the vexed question of the relation of alcoholic fermentation to the metabolic processes of the higher plants and animals4 ,my thanks are due to the ,council of the ,royal ,society1 and to the ,publishers of the ,journal of ,physiology for permission to make use of blocks 7,figs4 #b1 #d and #g7 which have appeared in their publications4 ,a4 ,h4 ,,preface ,,to ,,the ,,second ,,edition4 ,in the ,new ,edition no change has been made in the scope of the work4 ,the rapid progress of the subject has1 however1 rendered necessary many additions to the text and a considerable increase in the bibliography4 ,a4 ,h4 _/,may_/1#aiad4 ,,contents4 ,,chapter ,,page ,i4 ,,historical ,,introduction #a ,,ii4 ,,zymase ,,and ,,its ,,properties #ah ,,iii4 ,,the ,,function ,,of ,,phosphates ,,in ,,alcoholic ,,fermentation #da ,,iv4 ,,the ,,co-,,enzyme ,,of ,,yeast-,,juice #ei ,v4 ,,action ,,of ,,some ,,inhibiting ,,and ,,accelerating ,,agents ,,on ,,the ,,enzymes ,,of ,,yeast-,,juice #gj ,,vi4 ,,carboxylase #ha ,,vii4 ,,the ,,by-,,products ,,of ,,alcoholic ,,fermentation #he ,,viii4 ,,the ,,chemical ,,changes ,,involved ,,in ,,fermentation #if ,,ix4 ,,the ,,mechanism ,,of ,,fermentation #aai ,,bibliography #acf ,,index #aee p#jja ,,chapter ,i4 ,,historical ,,introduction4 ,the problem of alcoholic fermentation1 of the origin and nature of that mysterious and apparently spontaneous change which converted the insipid juice of the grape into stimulating wine1 seems to have exerted a fascination over the minds of natural philosophers from the very earliest times4 ,no date can be assigned to the first observation of the phenomena of the process4 ,history finds man in the possession of alcoholic liquors1 and in the earliest chemical writings we find fermentation1 as a familiar natural process1 invoked to explain and illustrate the changes with which the science of those early days was concerned4 ,throughout the period of alchemy fermentation plays an important part2 it is1 in fact1 scarcely too much to say that the language of the alchemists and many of their ideas were founded on the phenomena of fermentation4 ,the subtle change in properties permeating the whole mass of material1 the frothing of the fermenting liquid1 rendering evident the vigour of the action1 seemed to them the very emblems of the mysterious process by which the long sought for philosopher's stone was to convert the baser metals into gold4 ,as chemical science emerged from the mists of alchemy1 definite ideas about the nature of alcoholic fermentation and of putrefaction began to be formed4 ,fermentation was distinguished from other chemical changes in which gases were evolved1 such as the action of acids on alkali carbonates 7,sylvius de le ,bo1 #afei72 the gas evolved was examined and termed gas vinorum1 and was distinguished from the alcohol with which it had at first been confused 7van ,helmont1 #afdh72 afterwards it was found that like the gas from potashes it was soluble in water 7,wren1 #affd74 ,the gaseous product of fermentation and putrefaction was identified by ,mac,bride1 in #agfd1 with the fixed air of ,black1 whilst ,cavendish in #agff showed that fixed air alone was evolved in alcoholic fermentation and that a mixture of this with inflammable air was produced by putrefaction4 ,in the meantime it had been recognised that only sweet liquors could be fermented 7,ubi notandum1 nihil fermentare quod non sit dulce1 ,becher1 #afhb71 and finally ,cavendish p#jjb #aggf determined the proportion of fixed air obtainable from sugar by fermentation and found it to be #eg per cent4 ,it gradually became recognised that fermentation might yield either spirituous or acid liquors1 whilst putrefaction was thought to be an action of the same kind as fermentation1 differing mainly in the character of the products 7,becher74 ,as regards the nature of the process very confused ideas at first prevailed1 but in the time of the phlogistic chemists a definite theory of fermentation was proposed1 first by ,willis 7#afei7 and afterwards by ,stahl #afig1 the fundamental idea of which survived the overthrow of the phlogistic system by ,lavoisier and formed the foundation of the views of ,liebig4 ,to explain the spontaneous origin of fermentation and its propagation from one liquid to another1 they supposed that the process consisted in a violent internal motion of the particles of the fermenting substance1 set up by an aqueous liquid1 whereby the combination of the essential constituents of this material was loosened and new particles formed1 some of which were thrust out of the liquid 7the carbon dioxide7 and others retained in it 7the alcohol74 ,stahl specifically states that a body in such a state of internal disquietude can very readily communicate the disturbance to another1 which is itself at rest but is capable of undergoing a similar change1 so that a putrefying or fermenting liquid can set another liquid in putrefaction or fermentation4 ,taking account of the gradual accumulation of fact and theory we find at the time of ,lavoisier1 from which the modern aspect of the problem dates1 that ,stahl's theoretical views were generally accepted4 ,alcoholic fermentation was known to require the presence of sugar and was thought to lead to the production of carbon dioxide1 acetic acid1 and alcohol4 ,the composition of organic compounds was at that time not understood1 and it was ,lavoisier who established the fact that they consisted of carbon1 hydrogen1 and oxygen1 and who made systematic analyses of the substances concerned in fermentation 7#aghd-aghi74 ,lavoisier #aghi applied the results of these analyses to the study of alcoholic fermentation1 and by employing the principle which he regarded as the foundation of experimental chemistry1 that there is the same quantity of matter before and after the operation1 he drew up an equation between the quantities of carbon1 hydrogen1 and oxygen in the original sugar and in the resulting substances1 alcohol1 carbon dioxide1 and acetic acid1 showing that the products contained the whole matter of the sugar1 and thus for the first time giving a clear view of the chemical p#jjc change which occurs in fermentation4 ,the conclusion to which he came was1 we now know1 very nearly accurate1 but the research must be regarded as one of those remarkable instances in which the genius of the investigator triumphs over experimental deficiencies1 for the analytical numbers employed contained grave errors1 and it was only by a fortunate compensation of these that a result so near the truth was attained4 ,lavoisier's equation or balance sheet was as follows3-- ,carbon4 ,hydrogen4 ,oxygen4 #iei pounds of sugar 7cane sugar7 consist #bfh #gg #fad of ,these yield3-- #egg pounds of alcohol containing #afg #if #cad #cec carbon dioxide containing #ii -- #bed #be acetic acid containing #jf #jb #ag ----- ---- ----- ,total contained in products #bgb #ih #ehe ,the true composition of the sugar used was carbon #djd1 hydrogen #fa1 oxygen #did4 ,lavoisier expressed no view as to the agency by which fermentation was brought about1 but came to a very definite and characteristic conclusion as to the chemical nature of the change4 ,the sugar1 which he regarded in harmony with his general views as an oxide1 was split into two parts1 one of which was oxidised at the expense of the other to form carbonic acid1 whilst the other was deoxygenised in favour of the former to produce the combustible substance alcohol1 so that if it were possible to recombine these two substances1 alcohol and carbonic acid1 sugar would result4 ,from this point commences the modern study of the problem4 ,provided by the genius of ,lavoisier with the assurance that the hitherto mysterious process of fermentation was to be ranked along with familiar chemical changes1 and that it proceeded in harmony with the same quantitative laws as these simpler reactions1 chemists were stimulated in their desire to penetrate further into the mysteries of the phenomenon1 and the importance and interest of the problem attracted many workers4 ,so important indeed did the matter appear to ,lavoisier's countrymen that in the year #h of the ,french ,republic 7#ahjj7 a prize--consisting of a gold medal1 the value of which1 expressed in terms of the newly introduced metric system1 was that of one kilogram of gold--was offered by the ,institute for the best answer to the question3 ,what are the characteristics by which animal and vegetable substances which act as ferments can be distinguished from those which they are capable of fermenting8 p#jjd ,this valuable prize was again offered in #ahjb but was never awarded1 as the fund from which it was to be drawn was sequestrated from the ,institute in #ahjd4 ,the first response to this stimulating offer was an important memoir by citizen ,thenard #ahjc1 which provided many of the facts upon which ,liebig subsequently based his views4 ,thenard combats the prevailing idea1 first expressed by ,fabroni 7#aghg-agii71 that fermentation is caused by the action of gluten derived from grain on starch and sugar1 but is himself uncertain as to the actual nature of the ferment4 ,he points out that all fermenting liquids deposit a material resembling brewer's yeast1 and he shows that this contains nitrogen1 much of which is evolved as ammonia on distillation4 ,his most important result is1 however1 that when yeast is used to ferment pure sugar1 it undergoes a gradual change and is finally left as a white mass1 much reduced in weight1 which contains no nitrogen and is without action on sugar4 ,thenard1 moreover1 it is interesting to note1 differs from ,lavoisier1 inasmuch as he ascribes the origin of some of the carbonic acid to the carbon of the ferment1 an opinion which was still held in various degrees by many investigators 7see ,seguin1 quoted by ,thenard74 ,thenard's memoir was followed by a communication of fundamental importance from ,gay-,lussac #ahaj4 ,a process for preserving food had been introduced by ,appert1 which consisted in placing the material in bottles1 closing these very carefully and exposing them to the temperature of boiling water for some time4 ,gay-,lussac was struck by the fact that when such a bottle was opened fermentation or putrefaction set in rapidly4 ,analysis of the air left in such a sealed bottle showed that all the oxygen had been absorbed1 and these facts led to the view that fermentation was set up by the action of oxygen on the fermentable material4 ,experiment appeared to confirm this in the most striking way4 ,a bottle of preserved grape-juice was opened over mercury and part of its contents passed through the mercury into a bell-jar containing air1 the remainder into a similar vessel free from air4 ,in the presence of air fermentation set in at once1 in the absence of air no fermentation whatever occurred4 ,this connection between fermentation and the presence of air was established by numerous experiments and appeared incontestable4 ,fermentation1 it was found1 could be checked by boiling even after the addition of oxygen1 and hence food could be preserved in free contact with the air1 provided only that it was raised to the temperature of boiling water at short intervals of time4 ,gay-,lussac's opinion was that the ferment was formed by the action of the oxygen on the p#jje liquid1 and that the product of this action was altered by heat and rendered incapable of producing fermentation1 as was also brewer's yeast1 which1 however1 he regarded1 on account of its insolubility1 as different from the soluble ferment which initiated the change in the limpid grape-juice4 ,colin1 on the other hand #ahbe1 recognised that alcoholic fermentation by whatever substance it was started1 resulted in the formation of an insoluble deposit more active than the original substance1 and he suggested that this deposit might possibly in every case be of the same nature4 ,so far no suspicion appears to have arisen in the minds of those who had occupied themselves with the study of fermentation that this change differed in any essential manner from many other reactions familiar to chemists4 ,the origin and properties of the ferment were indeed remarkable and involved in obscurity1 but the uncertainty regarding this substance was no greater than that surrounding many1 if not all1 compounds of animal and vegetable origin4 ,although1 however1 the purely chemical view as to the nature of yeast was generally recognised and adopted1 isolated observations were not wanting which tended to show that yeast might be something more than a mere chemical reagent4 ,as early as #afhj in letters to the ,royal ,society ,leeuwenhoek described the microscopic appearance of yeast of various origins as that of small1 round1 or oval particles1 but no further progress seems to have been made in this direction for nearly a century and a half1 when we find that ,desmazires #ahbf examined the film formed on beer1 figured the elongated cells of which it was composed1 and described it under the name of ,mycoderma ,cerevisi4 ,he1 however1 regarded it rather as of animal than of vegetable origin1 and does not appear to have connected the presence of these cells with the process of fermentation4 ,upon this long period during which yeast was regarded merely as a chemical compound there followed1 as has so frequently occurred in similar cases1 a sudden outburst of discovery4 ,no less than three observers hit almost simultaneously upon the secret of fermentation and declared that yeast was a living organism4 ,first among these in strict order of time was ,cagniard-,latour #ahch1 who made a number of communications to the ,academy and to the ,socit ,philomatique in #ahce-f1 the contents of which were collected in a paper presented to the ,academy of ,sciences on #ab ,june1 #ahcg1 and published in #ahch4 ,the observations upon which this memoir was based were almost exclusively microscopical4 ,yeast was recognised as consisting of spherical particles1 which were capable of p#jjf reproduction by budding but incapable of motion1 and it was therefore regarded as a living organism probably belonging to the vegetable kingdom4 ,alcoholic fermentation was observed to depend on the presence of living yeast cells1 and was attributed to some effect of their vegetative life 7quelque effet de leur vgtation74 ,it was also noticed that yeast was not deprived of its fermenting power by exposure to the temperature of solid carbonic acid1 a sample of which was supplied to ,cagniard-,latour by ,thilorier1 who had only recently prepared it for the first time4 ,theodor ,schwann #ahcg1 whose researches were quite independent of those of ,cagniard-,latour1 approached the problem from an entirely different point of view4 ,during the year #ahcf ,franz ,schulze #ahcf published a research on the subject of spontaneous generation1 in which he proved that when a solution containing animal or vegetable matter was boiled1 no putrefaction set in provided that all air which was allowed to have access to the liquid was previously passed through strong sulphuric acid4 ,schwann performed a very similar experiment by which he showed that this same result1 the absence of putrefaction1 was attained by heating all air which came into contact with the boiled liquid4 ,wishing to show that other processes in which air took part were not affected by the air being heated1 he made experiments with fermenting liquids and found1 contrary to his expectation1 that a liquid capable of undergoing vinous fermentation and containing yeast did not undergo this change after it had been boiled1 provided that1 as in the case of his previous experiments1 only air which had been heated was allowed to come into contact with it4 ,schwann's experiments on the prevention of putrefaction were unexceptionable and quite decisive4 ,the analogous experiments dealing with alcoholic fermentation were not quite so satisfactory4 ,yeast was added to a solution of cane sugar1 the flask containing the mixture placed in boiling water for ten minutes1 and then inverted over mercury4 ,about one-third of the liquid was then displaced by air and the flasks corked and kept inverted at air temperature4 ,in two flasks the air introduced was ordinary atmospheric air1 and in these flasks fermentation set in after about four to six weeks4 ,into the other two flasks air which had been heated was led1 and in these no fermentation occurred4 ,as described1 the experiment is quite satisfactory1 but ,schwann found on repetition that the results were irregular4 ,sometimes all the flasks showed fermentation1 sometimes none of them4 ,this was correctly ascribed to the experimental difficulties1 but none p#jjg the less served as a point of attack for hostile and damaging criticism at the hands of ,berzelius 7p4 #h74 ,the origin of putrefaction was definitely attributed by ,schwann to the presence of living germs in the air1 and the similarity of the result obtained with yeast suggested the idea that alcoholic fermentation was also brought about by a living organism1 a conception which was at once confirmed by a microscopical examination of a fermenting liquid4 ,the phenomena observed under the microscope were similar to those noted by ,cagniard-,latour1 and in accordance with these observations alcoholic fermentation was attributed to the development of a living organism1 the fermentative function of which was found to be destroyed by potassium arsenite and not by extract of ,nux vomica1 so that the organism was regarded rather as of vegetable than of animal nature4 ,this plant received the name of ,zuckerpilz or sugar fungus 7which has been perpetuated in the generic term ,saccharomyces74 ,alcoholic fermentation was explained as the decomposition brought about by this sugar fungus removing from the sugar and a nitrogenous substance the materials necessary for its growth and nourishment1 whilst the remaining elements of these compounds1 which were not taken up by the plant1 combined chiefly to form alcohol4 ,ktzing's memoir1 the third of the trio #ahcg1 also dates from #ahcg1 and his opinions1 like those of ,cagniard-,latour1 are founded on microscopical observations4 ,he recognises yeast as a vegetable organism and accurately describes its appearance4 ,alcoholic fermentation depends on the formation of yeast1 which is produced when the necessary elements and the proper conditions are present and then propagates itself4 ,the action on the liquid thus increases and the constituents not required to form the organism combine to form unorganised substances1 the carbonic acid and alcohol4 ,it is obvious1 says ,ktzing1 in a passage which roused the sarcasm of ,berzelius1 that chemists must now strike yeast off the roll of chemical compounds1 since it is not a compound but an organised body1 an organism4 ,these three papers1 which were published almost simultaneously1 were received at first with incredulity4 ,berzelius1 at that time the arbiter and dictator of the chemical world1 reviewed them all in his ,jahresbericht for #ahci #ahci with impartial scorn4 ,the microscopical evidence was denied all value1 and yeast was no more to be regarded as an organism than was a precipitate of alumina4 ,schwann's experiment 7p4 #f7 was criticised on the ground that the fermenting power of the added yeast had been only partially destroyed in the p#jjh flasks in which fermentation ensued1 completely in those which remained unchanged1 the admission of heated or unheated air being indifferent1 a criticism to some extent justified by ,schwann's statement1 already quoted1 of the uncertain result of the experiment4 ,berzelius himself regarded fermentation as being brought about by the yeast by virtue of that catalytic force1 which he had supposed to intervene in so many reactions1 both between substances of mineral and of animal and vegetable origin #ahcf1 and which enabled bodies1 by their mere presence1 and not by their affinity1 to arouse affinities ordinarily quiescent at the temperature of the experiment1 so that the elements of a compound body arrange themselves in some different way1 by which a greater degree of electro-chemical neutralisation is attained4 ,to the scorn of ,berzelius was soon added the sarcasm of ,whler and ,liebig #ahci4 ,stimulated in part by the publications of the three authors already mentioned1 and in part by the report of ,turpin #ahch1 who at the request of the ,academy of ,sciences had satisfied himself by observation of the accuracy of ,cagniard-,latour's conclusions1 ,whler prepared an elaborate skit on the subject1 which he sent to ,liebig1 to whom it appealed so strongly that he added some touches of his own and published it in the ,annalen1 following immediately upon a translation of ,turpin's paper4 ,yeast was here described with a considerable degree of anatomical realism as consisting of eggs which developed into minute animals1 shaped like a distilling apparatus1 by which the sugar was taken in as food and digested into carbonic acid and alcohol1 which were separately excreted1 the whole process being easily followed under the miscroscope4 ,close upon this pleasantry followed a serious and important communication from ,liebig #ahci1 in which the nature of fermentation1 putrefaction1 and decay was exhaustively discussed4 ,liebig did not admit that these phenomena were caused by living organisms1 nor did he attribute them like ,berzelius to the catalytic action of a substance which itself survived the reaction unchanged4 ,as regards alcoholic fermentation1 ,liebig's chief arguments may be briefly summarised4 ,as the result of alcoholic fermentation1 the whole of the carbon of the sugar reappears in the alcohol and carbon dioxide formed4 ,this change is brought about by a body termed the ferment1 which is formed as the result of a change set up by the access of air to plant juices containing sugar1 and which contains all the nitrogen of the nitrogenous constituents of the juice4 ,this ferment is a substance remarkably susceptible of change1 which undergoes an uninterrupted and progressive metamorphosis1 of p#jji the nature of putrefaction or decay1 and produces the fermentation of the sugar as a consequence of the transformation which it is itself undergoing4 ,the decomposition of the sugar is therefore due to a condition of instability transferred to it from the unstable and changing ferment1 and only continues so long as the decomposition of the ferment proceeds4 ,this communication of instability from one substance undergoing chemical change to another is the basis of ,liebig's conception1 and is illustrated by a number of chemical analogies1 one of which will suffice to explain his meaning4 ,platinum is itself incapable of decomposing nitric acid and dissolving in it2 silver1 on the other hand1 possesses this power4 ,when platinum is alloyed with silver1 the whole mass dissolves in nitric acid1 the power possessed by the silver being transferred to the platinum4 ,in like manner the condition of active decomposition of the ferment is transferred to the sugar1 which by itself is quite stable4 ,the central idea is that of ,stahl 7p4 #b7 which was thus reintroduced into scientific thought4 ,in a pure sugar solution the decomposition of the ferment soon comes to an end and fermentation then ceases4 ,in beer wort or vegetable juices1 on the other hand1 more ferment is continually formed in the manner already described from the nitrogenous constituents of the juice1 and hence the sugar is completely fermented away and unexhausted ferment left behind4 ,liebig's views were reiterated in his celebrated ,chemische ,briefe1 and became the generally accepted doctrine of chemists4 ,there seems little doubt that both ,berzelius and ,liebig in their scornful rejection of the results of ,cagniard-,latour1 ,schwann and ,ktzing1 were influenced1 perhaps almost unconsciously1 by a desire to avoid seeing an important chemical change relegated to the domain of that vital force from beneath the sway of which a large part of organic chemistry had just been rescued by ,whler's brilliant synthetical production of urea and by the less recognised synthesis of alcohol by ,hennell 7see on this point ,ahrens #aijb74 ,a strong body of evidence1 however1 gradually accumulated in favour of the vegetable nature of yeast1 so that it may be said that by #ahdh a powerful minority adhered to the views of ,cagniard-,latour1 ,schwann1 and ,ktzing see ,schrohe1 #aijd1 p4 #bah1 and compare ,buchner1 #aijd4 ,among these must be included ,berzelius #ahdh1 who had so forcibly repudiated the idea only ten years before1 whereas ,liebig in the #ahea edition of his letters does not mention the fact that yeast is a living organism 7,letter ,,xv74 ,the recognition of the vegetable nature of yeast1 however1 by no p#jaj means disproved ,liebig's view of the nature of the change by which sugar was converted into carbon dioxide and alcohol1 as was carefully pointed out by ,schlossberger #ahdd in a research on the nature of yeast1 carried out in ,liebig's laboratory but without decisive results4 ,mitscherlich was also convinced of the vegetable character of yeast1 and showed #ahda that when yeast was placed in a glass tube closed by parchment and plunged into sugar solution1 the sugar entered the glass tube and was there fermented1 but was not fermented outside the tube4 ,he regarded this as a proof that fermentation only occurred at the surface of the yeast cells1 and explained the process by contact action in the sense of the catalytic action of ,berzelius1 rather than by ,liebig's transference of molecular instability4 ,similar results were obtained with an animal membrane by ,helmholtz #ahdc1 who also expressed his conviction that yeast was a vegetable organism4 ,in #ahed ,schrder and von ,dusch #ahed1 #ahei1 #ahfa strongly reinforced the evidence in favour of this view by succeeding in preventing the putrefaction and fermentation of many boiled organic liquids by the simple process of filtering all air which had access to them through cotton-wool4 ,these experiments1 which were continued until #ahfa1 led to the conclusion that the spontaneous alcoholic fermentation of liquids was due to living germs carried by the air1 and that when the air was passed through the cotton-wool these germs were held back4 ,at the middle of the nineteenth century opinions with regard to alcoholic fermentation1 notwithstanding all that had been done1 were still divided4 ,on the one hand ,liebig's theory of fermentation was widely held and taught4 ,gerhardt1 for example1 as late as #ahef in the article on fermentation in his treatise on organic chemistry #ahef1 gives entire support to ,liebig's views1 and his treatment of the matter affords an interesting glimpse of the arguments which were then held to be decisive4 ,the grounds on which he rejects the conclusions of ,schwann and the other investigators who shared the belief in the vegetable nature of yeast are that1 although in some cases animal and vegetable matter and infusions can be preserved from change by the methods described by these authors1 in others they cannot1 a striking case being that of milk1 which even after being boiled becomes sour even in filtered air1 and this without showing any trace of living organisms4 ,the action of heat1 sulphuric acid1 and filtration on the air is to remove1 or destroy1 not living organisms but particles of decomposing matter1 that is to say1 ferments which would add their activity to that of the oxygen of the air4 ,moreover1 many ferments1 as for example diastase1 act without p#jaa producing any insoluble deposit whatever which can be regarded as an organism4 ,evidemment1 he concludes1 la thorie de ,m4 ,liebig explique seule tous les phnomnes de la manire la plus complte et la plus logique2 c'est elle que tous les bons esprits ne peuvent manquer de se rallier4 ,on the other hand it was held by many to have been shown that ,liebig's view of the origin of yeast by the action of the air on a vegetable infusion was erroneous1 and that fermentation only arose when the air transferred to the liquid an active agent which could be removed from it by sulphuric acid 7,schulze71 by heat 7,schwann71 and by cotton-wool 7,schrder and von ,dusch74 ,accompanying alcoholic fermentation there was a development of a living organism1 the yeast1 and fermentation was believed1 without any very strict proof1 to be a phenomenon due to the life and vegetation of this organism4 ,this doctrine seems indeed ,schrohe1 #aijd to have been widely taught in ,germany from #ahdj-ef1 and to have established itself in the practice of the fermentation industries4 ,in #aheg commenced the classical researches of ,pasteur which finally decided the question as to the origin and functions of yeast and led him to the conclusion that alcoholic fermentation is an act correlated with the life and organisation of the yeast cells1 not with the death or putrefaction of the cells1 any more than it is a phenomenon of contact1 in which case the transformation of sugar would be accomplished in presence of the ferment without yielding up to it or taking from it anything #ahfj4 ,it is impossible here to enter in detail into ,pasteur's experiments on this subject1 or indeed to do more than indicate the general lines of his investigation4 ,his starting-point was the lactic acid fermentation4 ,the organism to which this change was due had hitherto escaped detection1 and as we have seen the spontaneous lactic fermentation of milk was one of the phenomena adduced by ,gerhardt 7p4 #aj7 in favour of ,liebig's views4 ,pasteur #aheg discovered the lactic acid producing organism and convinced himself that it was in fact a living organism and the active cause of the production of lactic acid4 ,one of the chief buttresses of ,liebig's theory was thus removed1 and ,pasteur next proceeded to apply the same method and reasoning to alcoholic fermentation4 ,liebig's theory of the origin of yeast by the action of the oxygen of the air on the nitrogenous matter of the fermentable liquid was conclusively and strikingly disproved by the brilliant device of producing a crop of yeast in a liquid medium containing only comparatively p#jab simple substances of known composition--sugar1 ammonium tartrate and mineral phosphate4 ,here there was obviously present in the original medium no matter which could be put into a state of putrefaction by contact with oxygen and extend its instability to the sugar4 ,any such material must first be formed by the vital processes of the yeast4 ,in the next place ,pasteur showed by careful analyses and estimations that1 whenever fermentation occurred1 growth and multiplication of yeast accompanied the phenomenon4 ,the sugar1 he proved1 was not completely decomposed into carbon dioxide and alcohol1 as had been assumed by ,liebig 7p4 #h74 ,a balance-sheet of materials and products was constructed which showed that the alcohol and carbon dioxide formed amounted only to about #ie per cent4 of the invert sugar fermented1 the difference being made up by glycerol1 succinic acid1 cellulose1 and other substances #ahfj1 p4 #cdg4 ,in every case of fermentation1 even when a paste of yeast was added to a solution of pure cane sugar in water1 the yeast was found by quantitative measurements to have taken something from the sugar4 ,this something was indeterminate in character1 but1 including the whole of the extractives which had passed from the yeast cells into the surrounding liquid1 it amounted to as much as #afc per cent4 of the weight of the sugar fermented #ahfj1 p4 #cdd4 ,pasteur was therefore led to consider fermentation as a physiological process accompanying the life of the yeast4 ,his conclusions were couched in unmistakable words3 ,the chemical act of fermentation is essentially a phenomenon correlative with a vital act1 commencing and ceasing with the latter4 ,i am of opinion that alcoholic fermentation never occurs without simultaneous organisation1 development1 multiplication of cells1 or the continued life of cells already formed4 ,the results expressed in this memoir seem to me to be completely opposed to the opinions of ,liebig and ,berzelius4 ,if ,i am asked in what consists the chemical act whereby the sugar is decomposed and what is its real cause1 ,i reply that ,i am completely ignorant of it4 ,ought we to say that the yeast feeds on sugar and excretes alcohol and carbonic acid8 ,or should we rather maintain that yeast in its development produces some substance of the nature of a pepsin1 which acts upon the sugar and then disappears1 for no such substance is found in fermented liquids8 ,i have nothing to reply to these hypotheses4 ,i neither admit them nor reject them1 and wish only to restrain myself from going beyond the facts4 ,and the facts tell me simply that all true fermentations are correlative with physiological phenomena4 ,liebig felt to the full the weight of ,pasteur's criticisms2 his reply p#jac was long delayed #ahgj1 and1 according to his biographer1 ,volhard #aiji1 caused him much anxiety4 ,in it he admits the vegetable nature of yeast1 but does not regard ,pasteur's conclusion as in any way a solution of the problem of the nature of alcoholic fermentation4 ,pasteur's physiological act is for ,liebig the very phenomenon which requires explanation1 and which he still maintains can be explained by his original theory of communicated instability4 ,on some of ,pasteur's results1 notably the very important one of the cultivation of yeast in a synthetic medium1 he casts grave doubt1 whilst he explains the production of glycerol and succinic acid as due to independent reactions4 ,the phenomenon of fermentation is still for him one which accompanies the decomposition of the constituents of the cell1 rather than their building up by vegetative growth4 ,when the fungus ceases to grow1 the bond which holds together the constituents of the cell contents is relaxed1 and it is the motion which is thus set up in them which is the means by which the yeast cells are enabled to bring about a displacement or decomposition of the elements of sugar or other organic molecules4 ,pasteur replied in a brief and unanswerable note #ahgb4 ,all his attention was concentrated on the one question of the production of yeast in a synthetic medium1 which he recognised as fundamental4 ,the validity of this experiment he emphatically reaffirmed1 and finally undertook1 from materials supplied by ,liebig himself1 to produce as much yeast as could be reasonably desired4 ,this challenge was never taken up1 and this communication formed the last word of the controversy4 ,pasteur had at this time firmly established his thesis1 _/no fermentation without life_/1 both for alcoholic fermentation and for those other fermentations which are produced by bacteria1 and had put upon a sound and permanent basis the conclusions drawn by ,schulze1 ,cagniard-,latour1 ,schwann1 and ,ktzing from their early experiments4 ,it became generally recognised that putrefaction and other fermentative changes were due to specific organisms1 which produced them in the exercise of their vital functions4 ,pasteur subsequently #ahge came to the conclusion that fermentation was the result of life without oxygen1 the cells being able1 in the absence of free oxygen1 to avail themselves of the energy liberated by the decomposition of substances containing combined oxygen4 ,this view1 which did not involve any alteration of ,pasteur's original thesis but was an attempt to explain the physiological origin and function of fermentation1 gave rise to a prolonged controversy1 which cannot be further discussed in these pages4 p#jad ,nevertheless1 ,liebig's desire to penetrate more deeply into the nature of the process of fermentation remained in many minds1 and numerous endeavours were made to obtain further insight into the problem4 ,in spite of an entire lack of direct experimental proof1 the conception that alcoholic fermentation was due to the chemical action of some substance elaborated by the cell and not directly to the vital processes of the cell as a whole found strenuous supporters even among those who were convinced of the vegetable character of yeast4 ,as early as #ahcc diastase1 discovered still earlier by ,kirchhoff and ,dubrunfaut1 had been extracted by means of water from germinating barley and precipitated by alcohol as a white powder1 the solution of which was capable of converting starch into sugar1 but lost this power when heated ,payen and ,persoz1 #ahcc4 ,basing his ideas in part upon the behaviour of this substance1 ,moritz ,traube #aheh enunciated in the clearest possible manner the theory that all fermentations produced by living organisms are caused by ferments1 which are definite chemical substances produced in the cells of the organism4 ,he regarded these substances as being closely related to the proteins and considered that their function was to transfer the oxygen and hydrogen of water to different parts of the molecule of the fermentable substance and thus bring about that apparent intramolecular oxidation and reduction which is so characteristic of fermentative change and had arrested the attention of ,lavoisier and1 long after him1 of ,liebig4 ,traube's main thesis1 that fermentation is caused by definite ferments or enzymes1 attracted much attention1 and received fresh support from the separation of invertase in #ahfj from an extract of yeast by ,berthelot1 and from the advocacy and authority of this great countryman of ,pasteur1 who definitely expressed his opinion that insoluble ferments existed which could not be separated from the tissues of the organism1 and further1 that the organism could not itself be regarded as the ferment1 but only as the producer of the ferment #aheg1 #ahfj4 ,hoppe-,seyler #ahgf also supported the enzyme theory of fermentation1 but differed in some respects from ,traube as to the exact function of the ferment see ,traube1 #ahgg2 ,hoppe-,seyler1 #ahgg4 ,direct experimental evidence was1 however1 still wanting1 and ,pasteur's reiterated assertion #ahge that all fermentation phenomena were manifestations of the life of the organism remained uncontroverted by experience4 ,numerous and repeated direct experimental attacks had been made p#jae from time to time upon the problem of the existence of a fermentation enzyme1 but all had yielded negative or unreliable results4 ,as early as #ahdf a bold attempt had been made by ,ldersdorff #ahdf to ascertain whether fermentation was or was not bound up with the life of the yeast by grinding yeast and examining the ground mass4 ,a single gram of yeast was thoroughly ground1 the process lasting for an hour1 and the product was tested with sugar solution4 ,not a single bubble of gas was evolved4 ,a similar result was obtained in a repetition of the experiment by ,schmidt in ,liebig's laboratory #ahdg1 the grinding being continued in this case for six hours1 but the natural conclusion that living yeast was essential for fermentation was not accepted1 on the ground that during the lengthy process of trituration in contact with air the yeast had become altered and now no longer possessed the power of producing alcoholic fermentation1 but instead had acquired that of changing sugar into lactic acid see ,gerhardt1 #ahef1 p4 #ede4 ,similar experiments made in #ahga by ,marie von ,manassen #ahgb1 #ahig1 in which yeast was ground for six to fifteen hours with powdered rock crystal1 yielded products which fermented sugar1 but they contained unbroken yeast cells1 so that the results obtained could not be considered decisive ,buchner and ,rapp1 #ahih1 #a1 although ,frau von ,manassen herself drew from them and from others in which sugar solution was treated with heated yeast1 but not under aseptic conditions1 the conclusion that living yeast cells were not necessary for fermentation4 ,quite unsuccessful were also the attempts made to accomplish the separation of fermentation from the living cell by ,adolf ,mayer #ahgi1 p4 #ff1 and1 as we learn from ,roux1 by ,pasteur himself1 grinding1 freezing1 and plasmolysing the cells1 having in his hands proved alike in vain4 ,extraction by glycerol or water1 a method by which many enzymes can be obtained in solution1 gave no better results ,ngeli and ,loew1 #ahgh1 and the enzyme theory of alcoholic fermentation appeared quite unjustified by experiment4 ,having convinced himself of this1 ,ngeli #ahgi suggested a new explanation of the facts based on molecular-physical grounds4 ,according to this view1 which unites in itself some of the conceptions of ,liebig1 ,pasteur1 and ,traube1 fermentation is the transference of a state of motion from the molecules1 atomic groups1 and atoms of the compounds constituting the living plasma of the cell to the fermentable material1 whereby the equilibrium existing in the molecules of the latter is disturbed and decomposition ensues #ahgi1 p4 #bi4 p#jaf ,this somewhat complex idea1 whilst including1 as did ,liebig's theory1 ,stahl's fundamental conception of a transmission of a state of motion1 satisfies ,pasteur's contention that fermentation cannot occur without life1 and at the same time explains the specific action of different organisms by differences in the constitution of their cell contents4 ,the really essential part of ,ngeli's theory consisted in the limitation of the power of transference of molecular motion to the living plasma1 by which the failure of all attempts to separate the power of fermentation from the living cell was explained4 ,this was the special phenomenon which required explanation2 to account for this the theory was devised1 and when this was experimentally disproved1 the theory lost all significance4 ,for nearly twenty years no further progress was made1 and then in #ahig the question which had aroused so much discussion and conjecture1 and had given rise to so much experimental work1 was finally answered by ,eduard ,buchner1 who succeeded in preparing from yeast a liquid which1 in the complete absence of cells1 was capable of effecting the resolution of sugar into carbon dioxide and alcohol #ahig1 #a4 ,in the light of this discovery the contribution to the truth made by each of the great protagonists in the prolonged discussion on the problem of alcoholic fermentation can be discerned with some degree of clearness4 ,liebig's main contention that fermentation was essentially a chemical act was correct1 although his explanation of the nature of this act was inaccurate4 ,pasteur1 in so far as he considered the act of fermentation as indissolubly connected with the life of the organism1 was shown to be in error1 but the function of the organism has only been restricted by a single stage1 the active enzyme of alcoholic fermentation has so far only been observed as the product of the living cell4 ,nearest of all to the truth was ,traube1 who in #aheh enunciated the theorem1 which was only proved for alcoholic fermentation in #ahig1 that all fermentations produced by living organisms are due to ferments secreted by the cells4 ,buchner's discovery of zymase has introduced a new experimental method by means of which the problem of alcoholic fermentation can be attacked1 and the result has been that since #ahig a considerable amount of information has been gained with regard to the nature and conditions of action of the enzymes of the yeast cell4 ,it has been found that the machinery of fermentation is much more complex than had been surmised4 ,the enzyme zymase1 which is essential for fermentation1 cannot of itself bring about the alcoholic fermentation of sugar1 but is dependent on the presence of a second substance1 termed1 for p#jag want of a more reasonable name1 the co-enzyme4 ,the chemical nature and function of this mysterious coadjutor are still unknown1 but as it withstands the temperature of boiling water and is dialysable1 it is probably more simple in constitution than the enzyme4 ,this1 however1 is not all2 for the decomposition of sugar a phosphate is also indispensable4 ,it appears that in yeast-juice1 and therefore also most probably in the yeast cell1 the phosphorus present takes an active part in fermentation and goes through a remarkable cycle of changes4 ,the breakdown of sugar into alcohol and carbon dioxide is accompanied by the formation of a complex hexosephosphate1 and the phosphate is split off from this compound and thus again rendered available for action by means of a special enzyme1 termed hexosephosphatase4 ,in addition to this complex of ferments1 the cell also possesses special enzymes by which the zymase and the co-enzyme can be destroyed1 and1 further1 at least one substance1 known as an anti-enzyme1 which directly checks this destructive action4 ,it seems probable1 moreover1 that the decomposition of the sugar molecule takes place in stages1 although much doubt yet exists as to the nature of these4 ,at the present moment the subject remains one of the most interesting in the whole field of biological chemistry1 the limited degree of insight which has already been gained into the marvellous complexity of the cell lending additional zest to the attempt to penetrate the darkness which shrouds the still hidden mysteries4 p#jah ,,chapter ,,ii4 ,,zymase ,,and ,,its ,,properties4 ,,discovery ,,of ,,zymase4 ,the history of ,buchner's discovery is of great interest ,gruber1 #aijh2 ,hahn1 #aijh4 ,as early as #ahic ,hans and ,eduard ,buchner found that the cells of even the smallest micro-organism could be broken by being ground with sand ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 p4 #bj1 and in #ahif the same process was applied by these two investigators to yeast1 with the object of obtaining a preparation for therapeutic purposes4 ,difficulties arose in the separation of the cell contents from the ground-up mixture of cell membranes1 unbroken cells1 and sand1 but these were overcome by carrying out the suggestion of ,martin ,hahn 7at that time assistant to ,hans ,buchner7 that kieselguhr should be added and the liquid squeezed out by means of a hydraulic press ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 p4 #eh4 ,the yeast-juice thus obtained was1 in the first instance1 employed for animal experiments1 but underwent change very rapidly4 ,the ordinary antiseptics were found to be unsuitable1 and hence sugar was added as a preservative1 and it was the marked action of the juice upon this added cane sugar that drew ,eduard ,buchner's attention to the fact that fermentation was proceeding in the absence of yeast-cells4 ,as in the case of so many discoveries1 the new phenomenon was brought to light1 apparently by chance1 as the result of an investigation directed to quite other ends1 but fortunately fell under the eye of an observer possessed of the genius which enabled him to realise its importance and give to it the true interpretation4 ,in his first papers #ahig1 #a1 #b2 #ahih1 ,buchner established the following facts3 7#a7 yeast-juice free from cells is capable of producing the alcoholic fermentation of glucose1 fructose1 cane sugar1 and maltose2 7#b7 the fermenting power of the juice is neither destroyed by the addition of chloroform1 benzene1 or sodium arsenite ,hans ,buchner1 #ahig1 by filtration through a ,berkefeld filter1 by evaporation to dryness at #cj to #ce1 nor by precipitation with alcohol2 7#c7 the fermenting power is completely destroyed when the liquid is heated to #ej4 p#jai ,from these facts he drew the conclusion that the production of alcoholic fermentation does not require so complicated an apparatus as the yeast cell1 and that the fermentative power of yeast-juice is due to the presence of a dissolved substance4 ,to this active substance he gave the name of zymase4 ,buchner's discovery was not received without some hesitation4 ,a number of investigators prepared yeast-juice1 but failed to obtain an active product ,will1 #ahig2 ,delbrck1 #ahig2 ,martin and ,chapman1 #ahih2 ,reynolds ,green1 #ahig2 ,lintner1 #ahii4 ,a more accurate knowledge of the necessary conditions and of the properties of yeast-juice1 however1 led to more successful results ,will1 #ahih2 ,reynolds ,green1 #ahih2 ,lange1 #ahih1 and it was soon established that1 given suitable yeast1 an active preparation could be readily procured by ,buchner's method4 ,criticism was then directed to the effect of the admitted presence of a certain number of micro-organisms in yeast-juice ,stavenhagen1 #ahig1 but ,buchner ,buchner and ,rapp1 #ahig was able to show by experiments in the presence of antiseptics and with juice filtered through a ,chamberland candle that the fermentation was not due to living organisms of any kind4 ,the most weighty criticism of ,buchner's conclusion consisted in an attempt to show that the properties of yeast-juice might be due to the presence1 suspended in it1 of fragments of living protoplasm1 which1 although severed from their original surroundings in the cell1 might retain for some time the power of producing alcoholic fermentation4 ,this1 it will be seen1 was an endeavour to extend ,ngeli's theory to include in it the newly discovered fact4 ,in favour of this view were adduced the similarity between the effects of many antiseptics on living yeast and on the juice1 the ephemeral nature of the fermenting agent present in the juice1 the effect of dilution with water1 and the phenomenon of autofermentation which is exhibited by the juice in the absence of added sugar ,abeles1 #ahih2 v4 ,kupffer1 #ahig2 v4 ,voit1 #ahig2 ,wehmer1 #ahih2 ,neumeister1 #ahig2 ,macfadyen1 ,morris1 and ,rowland1 #aijj2 ,bokorny1 #aijf2 ,fischer1 #aijc2 ,beijerinck1 #ahig1 #aijj2 ,wroblewski1 #ahii1 #aija4 ,a brief general description of the actual properties of yeast-juice and of the phenomena of fermentation by its means is sufficient to show the great improbability of this view4 ,the juice prepared by ,buchner's method forms a somewhat viscous opalescent brownish-yellow liquid1 which is usually faintly acid in reaction compare ,ahrens1 #aijj and almost optically inactive4 ,it has a specific gravity of #ajc to #ajf1 contains #he to #ad per cent4 p#jbj of dissolved solids1 and leaves an ash amounting to #ad to #b per cent4 ,about #jg to #ag per cent4 of nitrogen is present1 nearly all in the form of protein1 which coagulates to a thick white mass when the juice is heated4 ,a powerful digestive enzyme of the type of trypsin is also present1 so that when the juice is preserved its albumin undergoes digestion at a rate which depends on the temperature ,hahn1 #ahih2 ,geret and ,hahn1 #ahih1 #a1 #b2 #aijj2 ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 pp4 #bhg-cdj1 and is converted into a mixture of bases and amino-acids4 ,after about six days at #cg1 or #aj to #ad days at the ordinary temperature1 the digestion is so complete that no coagulation occurs when the juice is boiled4 ,as this proteoclastic enzyme1 like the alcoholic enzyme1 cannot be extracted from the living cells1 it is termed yeast endotrypsin or endotryptase4 ,fresh yeast-juice produces a slow fermentation of sugar1 which lasts for forty-eight to ninety-six hours at #be to #cj1 about a week at the ordinary temperature1 and then ceases1 owing1 not to exhaustion of the sugar1 but to the disappearance of the fermenting agent4 ,when the juice is preserved or incubated in the absence of a fermentable sugar this disappearance occurs considerably sooner1 so that even after standing for a single day at room temperature1 or two days at #j1 no fermentation may occur when sugar is added4 ,the reason for this behaviour has not been definitely ascertained4 ,as will be seen later on 7p4 #fd7 the phenomenon is a complex one1 but the disappearance of the enzyme was originally ascribed by ,buchner to the digestive action upon it of the endotrypsin of the juice #ahig1 #b1 and no better explanation has yet been found4 ,confirmation of this view is afforded by the fact that the addition of a tryptic enzyme of animal origin greatly hastens the disappearance of the alcoholic enzyme ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 p4 #abf1 and that some substances which hinder the tryptic action favour fermentation ,harden1 #aijc4 ,the amount of fermentation produced is almost unaffected by the presence of such antiseptics as chloroform or toluene1 although some others1 such as arsenites and fluorides1 decrease it when added in comparatively high concentrations1 and it is only slightly diminished by dilution with three or four volumes of sugar solution1 somewhat more considerably by dilution with water4 ,when it is filtered through a ,chamberland filter the first portions of the filtrate are capable of bringing about fermentation1 but the fermenting power diminishes in the succeeding portions and finally disappears4 ,the juice can be spun in a centrifugal machine without being in any way altered1 and no separation into more or less active layers takes place under these conditions4 p#jba ,the amorphous powder obtained by drying the precipitate produced when the juice is added to a mixture of alcohol and ether is also capable of producing fermentation1 and the process of precipitation may be repeated without seriously diminishing the fermenting power of the product4 ,these facts clearly show that the various phenomena adduced by the supporters of the theory of protoplasmic fragments are quite consistent with the presence of a dissolved enzyme as the active agent of the juice1 and at the same time that the properties demanded of the living fragments of protoplasm to which fermentation is ascribed are such as cannot be reconciled with our knowledge of living matter4 ,if living protoplasm is the cause of alcoholic fermentation by yeast-juice1 a new conception of life will be necessary2 the properties of the postulated fragments of protoplasm must be so different from those which the protoplasm of the living cell possesses as to deprive the theory of all real value ,buchner1 #aijj1 #b2 ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 p4 #cc4 ,further and very convincing evidence against the protoplasm theory is afforded by the behaviour of yeast towards various desiccating agents4 ,when yeast is dried at the ordinary temperature it retains its vitality for a considerable period4 ,if1 however1 the dried yeast be heated for six hours at #ajj it loses the power of growth and reproduction but still retains that of fermenting sugar1 and when ground with sand1 kieselguhr and #aj per cent4 glycerol solution yields an active juice ,buchner1 #ahig1 #b2 #aijj1 #a4 ,preparations 7known as zymin7 obtained by treating yeast with a mixture of alcohol and ether ,albert1 #aijj1 #aija1 #a1 or with acetone and ether ,albert1 ,buchner1 and ,rapp1 #aijb1 show precisely similar properties 7p4 #ch74 ,the proof in this case has been carried a step further1 for the active juice obtained by grinding such acetone-yeast1 when precipitated with alcohol and ether1 yields an amorphous powder1 still capable of fermenting sugar4 ,,the ,,preparation ,,of ,,yeast-,,juice4 ,buchner's process for the preparation of active yeast-juice is characterised by extreme simplicity4 ,the yeast employed1 which should be fresh brewery yeast1 is washed two or three times by being suspended in a large amount of water and allowed to settle in deep vessels4 ,it is then collected on a filter cloth1 wrapped in a press cloth1 and submitted to a pressure of about #ej kilos1 per sq4 cm4 for five minutes4 ,the resulting friable mass contains about #gj per cent4 of water and is free from adhering wort4 ,the washed yeast is then p#jbb mixed with an equal weight of silver sand and #jb to #jc parts of kieselguhr1 care being taken that this is free from acid4 ,the correct amount of kieselguhr to be added can only be ascertained by experience1 and varies with different samples of yeast4 ,the dry powder thus obtained is brought in portions of #cjj to #djj grams into a large porcelain mortar and ground by hand by means of a porcelain pestle fastened to a long iron rod which passes through a ring fixed in the wall 7,fig4 #a74 ,the mortar used by ,buchner has a diameter of #dj cm4 and the pestle and rod together weigh #h kilos4 ,illustration3 ,,fig4 #a4 7,mortar and ,pestle--,ed47 ,as the grinding proceeds the light-coloured powder gradually darkens and becomes brown1 and the mass becomes moist and adheres to the pestle1 until finally1 after two to three minutes' grinding1 it takes the consistency of dough1 at which stage the process is stopped4 ,the mass is next enveloped in a press cloth and submitted to a pressure of #ij kilos1 per sq4 cm4 in a hydraulic hand press1 the pressure being very gradually raised in order to avoid rupture of the cloth4 ,the cloth required for #ajjj grams of yeast measures #fj by #ge cm4 and is previously soaked in water and then submitted to a pressure of #ej kilos1 per sq4 cm41 retaining about #ce to #dj c4c4 of water4 ,the juice runs from the press on to a folded filter paper1 to remove kieselguhr and yeast cells1 and passes into a vessel standing in ice water4 ,the yield of juice obtained by ,buchner in an operation of this kind from #a kilo4 of yeast amounts to #cbj to #dfj c4c4 ,it may be increased by re-grinding the press cake and again submitting it to pressure1 and then amounts on the average to #dej to #ejj c4c4 ,since the cell membranes constitute about #bj per cent4 of the weight of the dry yeast1 this yield corresponds to more than #fj per cent4 of the total cell contents of the yeast4 ,it has been computed by ,will quoted by ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 p4 #ff that p#jbc only about #bj per cent4 of the cells are left unaltered by one grinding and pressing1 and only #d per cent4 after a repetition of the process1 at least #eg per cent4 of the cells being actually ruptured by the double process1 and the remainder to some extent altered4 ,it seems probable from these figures that a certain amount of the juice may be derived from the unbroken cells1 and ,will expressly states that many unbroken cells have lost their vacuoles4 ,illustration3 ,,fig4 #b4 7,hydraulic ,hand ,press--,ed47 ,if the yeast be submitted to a process of regeneration1 which consists in exposure to a well-aerated solution of sugar and mineral salts until fermentation is complete1 the juice subsequently obtained p#jbd is more active than that yielded by the original yeast ,albert1 #ahii1 #a4 ,a modified method of grinding yeast was introduced by ,macfadyen1 ,morris1 and ,rowland #aijj1 who placed a mixture of yeast and sand in a jacketed and cooled vessel1 in which a spindle carrying brass flanges was rapidly rotated ,rowland1 #aija4 ,one kilo4 of yeast ground in this way for #ce hours yielded #cej c4c4 of juice4 ,this grinding process was at first adopted by ,harden and ,young in their experiments but was afterwards abandoned in favour of ,buchner's hand-grinding process1 as it was found liable to yield juices of low fermenting power1 probably on account of inefficient cooling during the grinding process4 ,a slight modification of ,buchner's process has1 however1 been introduced1 the hand-ground mass being mixed with a further quantity of kieselguhr until a nearly dry powder is formed1 and the mass packed between two layers of chain cloth in steel filter plates and pressed out in a hydraulic press at about #b tons to the square inch 7#cjj kilos4 per sq4 cm474 ,the press and plates are shown in section in ,fig4 #b4 ,it has also been found convenient to remove yeast cells and kieselguhr from the freshly pressed juice by centrifugalisation instead of by filtration through paper1 and to wash the yeast before grinding by means of a filter-press4 ,working with ,english top yeasts ,harden and ,young have found the yield of juice extremely variable1 the general rule being that the amount of juice obtainable from freshly skimmed yeast is smaller than that yielded by the same yeast after standing for a day or two after being skimmed4 ,the yield for #ajjj grams of pressed brewer's yeast varies from #aej to #cge c4c41 and is on the average about #bej c4c4 ,very fresh yeast occasionally presents the peculiar phenomenon that scarcely any juice can be expressed from the ground mass1 although the latter does not differ in appearance or consistency from a mass which gives a good yield4 ,,extraction ,,of ,,zymase ,,from ,,unground ,,yeast4 _/#a4 ,maceration of ,dried ,yeast4_/ ,a valuable addition to the methods of obtaining an active solution of zymase was made in #aiaa by ,lebedeff #aiaa1 #b2 #aiab1 #b2 see also #aiaa1 #c1 #g1 and #aiab1 #a4 ,this investigator had been in the habit of grinding dried yeast with water for preparing samples of yeast-juice of uniform character and observed that when the dried yeast was digested with sugar solution and the mixture heated1 coagulation p#jbe took place throughout the whole liquid1 the proteins of the yeast having passed out of the cells4 ,further examination revealed the interesting fact that dried yeast readily yielded an active extract when macerated in water for some time4 ,the quality of the resulting maceration extract depends on a considerable number of factors1 the chief of which are3 7#a7 the temperature of drying of the yeast2 7#b7 the temperature of maceration2 7#c7 the duration of maceration2 and 7#d7 the nature of the yeast1 as well as1 of course1 the amount of water added in maceration4 ,in general the yeast should be dried at #be-cj and then macerated with #c parts of water for #b hours at #ce4 ,the temperature of maceration may as a rule be varied1 without detriment to the product provided that the time of maceration is also suitably altered2 thus with dried ,munich yeast1 maceration for #de hours at #be is about as effective as #b hours at #ce1 whereas treatment for a shorter time at #be or a longer time at #ce produces in general a less efficacious extract4 ,yeast dried at a lower temperature than #be tends to yield an extract poor in co-enzyme 7p4 #ei7 and hence of low fermenting power1 this being especially marked at air temperature4 ,the subsequent treatment of the yeast during maceration may1 however1 be of great influence in such cases4 ,thus a yeast dried at #ae gave by maceration at #be for #de hours a weak extract 7yielding with excess of sugar #jcc;g4 ,,co#b71 whereas when macerated at #ce for #b hours it yielded a normal extract 7#acf;g4 ,,co#b74 ,the nature of the yeast is of paramount importance4 ,thus while ,munich 7bottom7 yeast usually gives a good result1 a top yeast from a ,paris brewery was found to yield extracts containing neither zymase nor its co-enzyme in whatever way the preparation was conducted4 ,the existence of such yeasts is of great interest1 and it was probably due to the unfortunate selection of such a yeast for his experiments that ,pasteur was unable to prepare active fermenting extracts and therefore failed to anticipate ,buchner by more than #cj years 7see p4 #ae74 ,the ,english top yeasts as a rule give poor results see ,dixon and ,atkins1 #aiac and sometimes yield totally inactive maceration extract4 ,it is not understood why the enzyme passes out of the cell during the process of maceration and the whole method gives rise to a number of extremely interesting problems4 _/,method4_/--,a suitable yeast is washed by decantation1 filtered through a cloth1 lightly pressed by means of a hand press1 and then passed through a sieve of #emm4 mesh1 spread out in a layer #a-ae;cm4 thick and left at #be-ce for two days4 ,fifty grams of the dried yeast is ,pg #jbf thoroughly and carefully mixed with #aej c4c4 of water in a basin by means of a spatula and the whole digested for two hours at #ce4 ,the mass often froths considerably4 ,it is then filtered through ordinary folded filter paper1 preferably in two portions1 and collected in a vessel cooled by ice4 ,the separation may also be effected by centrifuging or pressing out the mass1 and the maceration may be conveniently conducted in a flask immersed in the water of a thermostat4 ,it is not advisable to macerate more than #ej grams in one operation4 ,under these conditions #be-cj c4c4 of extract are obtained after #bj minutes' filtration1 #gj-hj c4c4 in twelve hours4 ,dried ,munich yeast can be bought from ,messrs4 ,schroder of ,munich and serves as a convenient source of the extract4#a #a ,the material supplied is occasionally found to yield an inactive extract and every sample should be tested4 ,this extract closely resembles in properties the juice obtained by grinding the same yeast1 but it is usually more active and contains more inorganic phosphate 7see p4 #df74 _/#b4 ,other ,methods4_/ ,attempts to prepare active extracts from undried yeast in an analogous manner have so far not been very successful4 ,thus ,rinckleben #aiaa found that plasmolysis by glycerol 7#h per cent47 or sodium phosphate 7#e per cent47 sometimes yielded an active juice and sometimes a juice which contained enzyme but no co-enzyme1 but more often an inactive juice incapable of activation 7p4 #fd7 see also ,kayser1 #aiaa4 ,giglioli #aiaa by the addition of chloroform also obtained an active liquid4 ,it appears in fact as though almost any method of plasmolysing the yeast cell may yield a certain proportion of zymase in the exudate4 ,an ingenious process has been devised by ,dixon and ,atkins #aiac who applied the method of freezing in liquid air which they had found efficacious for obtaining the sap from various plant organs4 ,they thus succeeded in obtaining from yeast1 derived from ,guinness' brewery in ,dublin1 liquids capable of fermenting sugar and of about the same efficacy as the maceration extracts prepared by ,lebedeff's method from the same yeast4 ,the results were1 however1 in both cases very low1 the maximum total production of ,,co#b by #be c4c4 of liquid from excess of sugar being #cbe c4c4 7air temperature7 or about #jjf;g4 ,munich yeast on the other hand yields1 either by maceration or grinding1 a liquid giving as much as #ae-b;g4 of ,,co#b per #be c4c41 whilst p#jbg ,english yeast-juice prepared by grinding often gives as much as #je-jg;g4 of ,,co#b4 ,no direct comparison with the juice prepared by grinding was made by ,dixon and ,atkins1 but it may be concluded from their results that the best method of obtaining an active preparation from the top yeasts used in this country is that of grinding4 ,maceration1 freezing and plasmolysis alike yield poor results4 ,with ,munich yeast on the other hand the maceration process yields excellent results1 whilst the liquid air process has not so far been tried4 ,,practical ,,methods ,,for ,,the ,,estimation ,,of ,,the ,,fermenting ,,power ,,of ,,yeast-,,juice4 ,in order to estimate the amount of carbon dioxide evolved in a given time and the total amount evolved by the action of yeast-juice on sugar1 ,buchner adopted an extremely simple method1 which consisted in carrying out the fermentation in an ,erlenmeyer flask provided with a small wash-bottle1 which contained sulphuric acid and was closed by a ,bunsen valve1 and ascertaining the loss of weight during the experiment4 ,corrections are necessary for the carbon dioxide present in the original juice and retained in the liquid at the close of the experiment and for that present in the air space of the apparatus1 but it was found that for most purposes these could be neglected4 ,in cases in which greater accuracy was desired1 the carbon dioxide was displaced by air before the weighings were made4 ,a typical experiment of this kind1 without displacement of carbon dioxide1 is the following3-- ,march #bb1 #ahii1 ,berlin bottom yeast ,v4 #bj c4c4 juice #h grams cane sugar #jb c4c4 toluene as antiseptic at #af4 ,grams of carbon dioxide after #bd #dh #gb #if hours4 #jdj #jfd #jii #aaa ,the total weight of carbon dioxide evolved under these conditions is termed the fermenting power of the juice 7,buchner74 ,a more accurate method ,macfadyen1 ,morris1 and ,rowland1 #aijj consists in passing the carbon dioxide into caustic soda solution and estimating it by titration4 ,the yeast-juice1 sugar1 and antiseptic are placed in an ,erlenmeyer flask provided with a straight glass tube1 through which air can be passed over the surface of the liquid1 and a conducting tube leading into a second flask which contains #ej c4c4 of #aj per cent4 caustic soda solution and is connected with the air by a guard tube containing soda lime4 ,the juice can be freed from carbon dioxide by agitation in a current of air before the flask is connected to p#jbh that containing the caustic soda solution1 and at the end of the period of incubation air is passed through the apparatus1 the liquid being boiled out if great accuracy is required4 ,the absorption flask is then disconnected and the amount of absorbed carbon dioxide estimated by titration4 ,this is carried out by making up the contents of the flask to #bjj c4c41 taking out an aliquot portion1 rendering this exactly neutral to phenophthalein by the addition first of normal and finally of decinormal acid1 adding methyl orange and titrating with decinormal acid to exact neutrality4 ,each c4c4 of decinormal acid used in this last titration represents #jjjdd gram of carbon dioxide in the quantity of solution titrated4 ,illustration3 ,,fig4 #c4 7,schiff's ,azotometer--,ed47 ,these methods are only suitable for observations at considerable intervals of time4 ,for the continuous observation of the course of fermentation ,harden1 ,thompson and ,young #aiaj connect the fermentation flask with a ,schiff's azotometer filled with mercury and measure the volume of gas evolved1 the liquid having been previously saturated with carbon dioxide 7,fig4 #c74 ,the level of the mercury in the reservoir is kept constant by a syphon overflow1 as shown in the figure1 or1 according to a modification introduced by ,s4 ,g4 ,paine1 by a specially constructed bottle provided with two tubulures near the bottom4 ,this ensures that no change in the pressure in the flask occurs1 and the volume of gas observed is reduced to normal pressure by means of a table4 ,before making a reading it is necessary to shake the fermenting mixture thoroughly1 as the albuminous liquid very readily becomes greatly supersaturated with carbon dioxide1 so much so in fact that very little gas is evolved in the intervals between the shakings4 ,the exact procedure in making an observation consists in shaking the flask p#jbi thoroughly1 replacing in the thermostat1 allowing to remain for one minute1 and then reading the level of the mercury in the azotometer4 ,after the required time1 say five minutes1 has elapsed from the time at which the flask was first shaken1 it is again removed from the bath1 shaken as before1 replaced1 allowed to remain for one minute and the reading then taken4 ,in this way readings can be conveniently made at intervals of three or five minutes or even less1 and much more detailed information obtained about the course of the reaction than is possible by means of observations made at intervals of several hours4 ,another form of volumetric apparatus1 designed by ,walton #aijd1 has been used by ,lebedeff #aiji4 ,an apparatus on a different principle has been designed by ,slator #aijf for use with living yeast1 but is equally applicable to yeast-juice1 and a very similar form has been more recently employed by ,iwanoff #aiji1 #b4 ,in this apparatus the change of pressure produced by the evolution of carbon dioxide is measured at constant volume1 and comparative rates of evolution can be obtained with considerable accuracy1 although the method has the disadvantage that the absolute volume of gas evolved is not measured4 ,the apparatus consists of a bottle or flask connected with a mercury manometer4 ,the fermenting mixture is placed in the bottle along with glass beads to facilitate agitation1 the pressure is reduced to a small amount by the water-pump1 and the rise of pressure is then observed at intervals1 this being proportional to the volume of gas produced4 ,as in the preceding case1 the liquid must be well shaken before a reading is made4 ,,the ,,alcoholic ,,fermentation ,,of ,,the ,,sugars ,,by ,,yeast-,,juice4 ,yeast-juice brings about a slow fermentation of those sugars which are fermented by the yeast from which it is prepared as well as of dextrin1 and of starch and glycogen1 which are not fermented by living yeast4 7_/a_/7 _/,relation to ,fermentation by living ,yeast4_/ ,both in rate of fermentation and in the total fermentation produced1 yeast-juice stands far behind the equivalent amount of living yeast4 ,taking #be c4c4 of yeast-juice to be equivalent to at least #cf grams of pressed yeast containing #gj per cent4 of moisture1 it is found that whereas the yeast-juice 7from ,english top yeast7 gives with glucose a maximum rate of fermentation of about #c c4c4 in five minutes1 the living yeast ferments the sugar at the rate of about #abf c4c4 in the same time1 or p#jcj about forty times as quickly4 ,the total carbon dioxide obtainable from the yeast-juice1 moreover1 corresponds to the fermentation of only #b to #c grams of sugar1 whilst the living yeast will readily ferment a much larger quantity1 although the exact limit in this respect has not been accurately determined4 ,the reasons for this great difference in behaviour will be discussed later on1 after the various factors concerned in fermentation have been considered 7p4 #abc74 7_/b_/7 _/,relation of ,alcohol to ,carbon ,dioxide4_/ ,in all cases of fermentation by yeast-juice and zymin1 the relative amounts of carbon dioxide and alcohol produced are substantially in the ratio of the molecular weights of the compounds1 that is as #dd3 #df1 so that for #a part of carbon dioxide #ajd of alcohol are formed4 ,this has been shown for the juice and zymin from bottom yeasts by ,buchner ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 pp4 #baj1 #baa1 who obtained the ratios #aja1 #jih1 #aja1 and #jii from experiments in which from #h to #ae grams of alcohol were produced4 ,similar numbers1 #jij1 #aab1 #jie1 #jia and #jib1 have been obtained for the juice from top yeasts by ,harden and ,young #aijd1 who worked with much smaller quantities4 ,the variable results obtained with juice from top yeast by ,macfadyen1 ,morris and ,rowland #aijj1 have not been confirmed4 7_/c_/7 _/,relation of ,carbon ,dioxide and ,alcohol ,produced to the ,amount of ,sugar ,fermented4_/ ,the construction of a balance-sheet between the sugar fermented and the products formed is of special interest in the case of alcoholic fermentation by yeast-juice1 because1 there being no cell growth as in the case of living yeast1 an opportunity appears to be afforded of ascertaining whether the whole of the sugar is converted into alcohol and carbon dioxide1 or whether some fraction of the sugar passes into any of the well-known subsidiary products of alcoholic fermentation by yeast1 such as glycerol1 fusel oil1 or succinic acid4 ,unfortunately the question cannot be settled in this way4 ,when the loss of sugar during the fermentation is estimated directly1 it is usually found to be considerably greater than the sum of the alcohol and carbon dioxide produced from it4 ,this fact was first observed by ,macfadyen1 ,morris and ,rowland #aijj1 and was then confirmed by ,buchner ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 p4 #bab1 in one instance1 the excess of sugar lost over products being in this case about #ae per cent4 of the total sugar which had disappeared4 ,the matter was then more thoroughly investigated by ,harden and ,young #aijd4 p#jca ,the conditions under which the experiment must be carried out are not very favourable to the attainment of extreme accuracy4 ,yeast-juice contains glycogen and a diastatic enzyme which converts this into dextrins and finally into sugar4 ,this process goes on throughout fermentation1 tending to increase the sugar present and to make the apparent loss of sugar less than the sum of the products4 ,in spite of this it was found that a certain amount of sugar invariably disappeared without being accounted for as alcohol or carbon dioxide1 and this whether the fermentation lasted sixty or a hundred and eight hours1 and independently of the dilution of the juice4 ,this disappearing sugar amounted in some cases to #dd per cent4 of the total loss of sugar1 and on the average of twenty-five experiments was #ch per cent4 ,further information was sought by converting all the sugar-yielding constituents of the juice into sugar by hydrolysis before and after the fermentation4 ,this process revealed the fact that when the glucose equivalent of the juice before and after fermentation was determined after hydrolysis with three times normal acid for three hours 7and a correction made for the loss of reducing power experienced by glucose itself when submitted to this treatment71 the difference was almost exactly equal to the alcohol and carbon dioxide produced4 ,in other words1 accompanying fermentation1 a change proceeds by which sugar is converted into a less reducing substance1 reconvertible into sugar by hydrolysis with acids4 ,similar results were subsequently obtained by ,buchner and ,meisenheimer #aijf1 who employed #ae normal acid and observed a small nett loss of sugar4 ,still more recently ,lebedeff #aiji1 #aiaj1 see also #aiac1 #b has carried out similar estimations with the same result4 ,it is doubtful whether the experiments which have so far been made on this point are sufficiently accurate to decide with certainty whether or not the loss of sugar is exactly equal to the sum of the carbon dioxide and alcohol produced4 ,it has been shown by ,buchner and ,meisenheimer #aijf that glycerol is a constant product of alcoholic fermentation by yeast-juice 7p4 #ie71 and no other source for this than the sugar has yet been found1 so that it is not improbable that a small amount of sugar is converted into non-carbohydrate substances other than carbon dioxide and alcohol4 ,it has also been shown ,harden and ,young1 #aiac that the deficit of sugar is not due to the formation of hexosephosphate 7p4 #dg71 which has a lower reduction than glucose1 and that the solution from which the sugar 7either glucose or fructose7 has disappeared actually contains some substance of relatively high dextrorotation and of low reducing power4 p#jcb ,however this may be1 it may be considered as established that during alcoholic fermentation sugar is converted by an enzyme into some compound of less reducing power1 which again yields sugar on hydrolysis with acids4 ,the exact nature of this substance has not been ascertained1 but it appears likely that the process is a synthetical one resulting in the formation of some polysaccharide1 possibly intermediate between the hexoses and glycogen4 ,a similar phenomenon has been observed with living yeast by ,euler and ,johansson #aiab1 #a1 and ,euler and ,berggren #aiab1 whose interpretation of the observation is discussed later on 7p4 #eg74 7_/d_/7 _/,fermentation of ,different ,carbohydrates4 ,autofermentation4_/ ,yeast-juice and zymin ferment all the sugars which are fermented by the yeast from which they are prepared1 and1 in addition1 a number of colloidal substances which cannot pass through the membrane of the living yeast cell1 but which are hydrolysed by enzymes in the juice and thus converted into simpler sugars capable of fermentation ,buchner and ,rapp1 #ahih1 #c2 #ahii1 #b4 ,of the simple sugars which have been examined1 glucose1 fructose1 and mannose are freely fermented1 l-arabinose not at all1 whilst the case of galactose is doubtful4 ,galactose is1 however1 fermented by juice prepared from a yeast which has been trained to ferment galactose ,harden and ,norris1 #aiaj4 ,as regards both the rate of fermentation and the total amount of carbon dioxide evolved from glucose and fructose by the action of a definite amount of yeast-juice1 ,buchner and ,rapp obtained practically identical numbers4 ,harden and ,young #aiji1 using juice from top yeast1 found that fructose was slightly more rapidly fermented and gave a somewhat larger total than glucose1 whilst mannose was initially fermented at almost the same rate as glucose1 but gave a decidedly lower total1 the following being the average result3-- ,sugar4 ,relative ,rates4 ,relative ,totals4 ,glucose #a #a ,fructose #abi #aae ,mannose #ajd #jfg ,among the disaccharides1 cane sugar and maltose are freely fermented1 and the juice can be shown like living yeast to contain invertase and maltase4 ,the extent of fermentation does not differ materially from that attained with glucose4 ,lactose is not fermented4 ,of the higher sugars raffinose is fermented by juice from bottom yeast1 but more slowly than cane sugar or maltose4 ,no experiments seem to have been made with juice from top yeast4 p#jcc ,as regards the fermentation of the higher carbohydrates1 very little experimental work has been carried out4 ,buchner and ,rapp found that the fermentation of starch paste was doubtful1 but that soluble starch and commercial dextrin were fermented with some freedom4 ,no special study has been made of the diastatic enzymes which bring about the hydrolysis of these substances4 ,the fermentation of glycogen by yeast-juice is of considerable interest1 since it is known that the characteristic reserve carbohydrate of the yeast cell is glycogen see ,harden and ,young1 #aijb1 where the literature is cited1 and moreover that in living yeast the intracellular fermentation of glycogen proceeds readily1 whereas glycogen added to a solution in which yeast is suspended is not affected4 ,yeast-juice contains a diastatic enzyme which hydrolyses glycogen to a reducing and fermentable sugar1 so that in a juice poor in zymase to which glycogen has been added1 the amount of sugar is found to increase1 the hydrolysis of the glycogen proceeding more quickly than the fermentation of the resulting sugar ,harden and ,young1 #aijd1 but the course of this enzymic hydrolysis of glycogen by yeast-juice has not yet been studied4 ,as a rule1 it is found both with juices from top and bottom yeast that the evolution of carbon dioxide from glycogen proceeds less rapidly and reaches a lower total than from an equivalent amount of glucose4 ,since nearly all samples of yeast contain glycogen1 yeast-juice and also zymin usually contain this substance as well as the products of its hydrolysis4 ,these provide a source of sugar which enters into alcoholic fermentation1 so that a slow spontaneous production of carbon dioxide and alcohol proceeds when yeast-juice is preserved without any addition of sugar4 ,the extent of this autofermentation varies considerably1 as might be expected1 with the nature of the yeast employed or the preparation of the material1 but is generally confined within the limits of #jjf to #je gram of carbon dioxide for #be c4c4 of juice4 ,in juice from bottom yeast it amounts to about #e to #aj per cent4 of the total fermentation obtainable with glucose ,buchner1 #aijj1 #b1 whereas in juice from top yeasts1 which gives a smaller total fermentation with glucose1 it may occasionally equal1 or even exceed1 the glucose fermentation1 and frequently amounts to #cj to #ej per cent4 of it4 ,it is therefore generally advisable in studying the effect of yeast-juice on any particular substance to ascertain the extent of autofermentation by means of a parallel experiment4 ,the maceration extract of ,lebedeff 7p4 #bd7 is usually1 but not invariably ,oppenheimer1 #aiad1 #b1 free from glycogen1 which is hydrolysed p#jcd and fermented during the processes of drying and macerating1 and therefore as a rule shows no appreciable autofermentation4 7_/e_/7 _/,effect of ,concentration of ,sugar on the ,total ,amount of ,fermentation4_/ ,the kinetics of fermentation by zymase will be considered later on 7p4 #abj71 but the effect on the total fermentation of different concentrations of sugar1 this substance being present throughout in considerable excess1 may be advantageously discussed at this stage4 ,the subject has been investigated by ,buchner ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 pp4 #aej-h2 ,buchner and ,rapp1 #ahig using cane sugar1 and he has found both for yeast-juice and for dried yeast-juice dissolved in water that 7_/a_/7 the total amount of fermentation increases with the concentration of the sugar2 7_/b_/7 the initial rate of fermentation decreases with the concentration of the sugar4 ,the following are the results of a typical experiment1 #bj c4c4 of yeast-juice being employed in presence of toluene at #bb3-- ,cane ,sugar4 ,,co#b in grams after ,weight4 ,per cent4 #f hours4 #bd hours4 #if hours4 #bb #aj #jag #jej #jee #ceb #ae #jad #jec #jfd #e #bj #jac #jed #jgc #fff #be #jac #jeb #jhj #hef #cj #jab #jdf #jha #ajgf #ce #jab #jdj #jhb #accc #dj #jaa #jcf #jhb #ajgf #ce #jab #jdj #jhb #accc #dj #jaa #jcf #jhb ,the results as to the total fermentations in experiments of this kind are liable to be vitiated by the circumstance that when a low initial concentration of sugar is employed1 the supply of sugar may be so greatly exhausted before the close of the experiment as to cause a marked diminution in the rate of fermentation and hence an unduly low total4 ,even allowing1 however1 for any effect of this kind1 the foregoing table clearly shows the increase in total fermentation and the decrease in initial rate accompanying the increase of sugar concentration from #aj to #dj per cent4 ,working with a greater range of concentrations 7#cc-ecc grm4 per #ajj c4c47 ,lebedeff has obtained similar results with maceration extract #aiaa1 #d1 but has found that the total amount fermented diminishes after a certain optimum concentration 7about #ccc grm4 per #ajj c4c47 is reached4 ,a practical conclusion from these experiments is that a high p#jce concentration of sugar tends to preserve the enzyme in an active state for a longer time4 ,simultaneously it prevents the development of bacteria and yeast cells4 7_/f_/7 _/,effect of ,varying ,concentration of ,yeast-,juice4_/ ,this subject1 which is of considerable importance with reference to the question of the protoplasmic or enzymic nature of the active agent in yeast-juice1 has been examined in some detail by ,buchner ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 pp4 #aeh-fe and by ,meisenheimer #aijc for juices from bottom yeast1 by ,harden and ,young #aijd for those from top yeast1 and by ,lebedeff #aiaa1 #d for maceration extract1 the results obtained being in substantial agreement4 ,dilution of yeast-juice with sugar solution1 so that the concentration of the sugar remains constant1 produces a small progressive diminution in the total fermentation1 which only becomes marked when more than #b volumes are added1 and this independently of the actual concentration of the sugar4 ,dilution with water produces a somewhat more decided diminution1 which1 however1 does not exceed #ej per cent4 of the total for the addition of #c volumes of water4 ,the effect on maceration extract is somewhat greater but of the same kind4 ,the autofermentation of juice from top yeast is scarcely affected by dilution with #d volumes of water4 ,nature of ,per cent4 ,volumes of ,volumes of ,total ,juice of ,sugar ,sugar ,water ,added4 ,fermentation 7#a1b1c7 ,employed ,solution in g4 by ,weight ,added4 of ,,co#b4 ,bottom ,yeast #a #bi #j -- #jii #a -- #aac #b -- #jib #d -- #jgi #b #i #j -- #jdc #a -- #jfj #b -- #jec #d -- #jda #c #i -- #j #jdf -- #a #jcb -- #b #jcc -- #c #jcf ,top ,yeast #a #j -- #j #jbi 7,autofermentation7 -- #b #jbi -- #c #jbh #b #bi #j -- #jca #a -- #jcd #b -- #jca #d -- #jce #f -- #jbh #c #gd -- #j #jdd -- #a #jce -- #b #jcj -- #c #jbh p#jcf ,on the whole1 therefore1 yeast-juice may be said to be only slightly affected by dilution even with pure water1 and the effect of the latter can in no way be regarded as comparable with the poisonous effect which it exerts on living protoplasm1 as suggested by ,macfadyen1 ,morris1 and ,rowland #aijj4 7_/g_/7 _/,the ,effect of ,antiseptics on the ,fermentation of ,sugars by ,yeast-,juice4_/ ,buchner has paid special attention to the effect of antiseptics on the course of fermentation by yeast-juice ,buchner and ,rapp1 #ahig2 #ahih1 #b1 #c2 #ahii1 #a2 ,buchner and ,antoni1 #aije1 #a2 ,buchner and ,hoffmann1 #aijg2 ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 pp4 #afi-bje2 see also ,albert1 #ahii1 #b2 ,gromoff and ,grigorieff1 #aijd2 ,duchaek1 #aiji in order 7#a7 to obtain evidence as to the possibility of the active agent in yeast-juice consisting of fragments of protoplasm and not of a soluble enzyme1 and 7#b7 also to provide a safe method of avoiding contamination1 by the growth of bacteria or yeasts1 of the liquids used which were often kept at #be for several days4 ,the results of these experiments are briefly summarised in the following table1 in which the effect of each substance on the total fermentation produced is noted3-- ,substance4 ,effect on ,total ,fermentation4 ,concentrated solution of glycerol ,slight diminution sugar increase ,toluene 7to saturation or excess7 ,less than #aj per cent4 diminution ,chloroform #je per cent4 ,slight increase #jh per cent4 7saturation7 ,no change ,large excess 7#ag per cent47 #fd per cent4 diminution ,chloral hydrate #jg per cent4 ,increase up to #bg per cent4 #ce-ed per cent4 ,completely destroyed ,phenol #ja per cent4 ,no change #je #dj per cent4 diminution #ab ,completely destroyed ,thymol #a ,slight diminution #e ,marked ,benzoic acid #ja #g per cent4 diminution #jbe #bf ,salicylic acid #ja #aj #jbg #ce ,formaldehyde #jab #bj #jbd #cj-fj ,acetone #f #bj #ad #hj ,alcohol #f #j-bj #ad #ge ,sodium fluoride #je #ij #b ,almost completely destroyed ,ammonium fluoride #jee per cent4 ,completely destroyed ,sodium azoimide1 ,na,n#c1 #jcf per cent4 ,slight diminution #jga ,marked ,quinine hydrochloride #a ,slight increase ,ozone #ajd-cdh milligrams per #bj c4c4 ,marked diminution ,hydrocyanic acid #ab per cent4 ,completely destroyed p#jcg ,the general result of these experiments is to show that quantities of antiseptics which are sufficient to inhibit the characteristic action of living cells have only a slight effect on the fermentative activity of yeast-juice4 ,a large excess of the antiseptic in many cases produces a very decided diminution or total destruction of the fermenting power1 and accompanying this a precipitation of the constituents of the juice4 ,the decided increase of activity produced by small quantities of chloral hydrate1 and to a less marked extent by chloroform and a few other substances1 is of considerable interest4 ,it is ascribed by ,duchaek to a selective action on the proteoclastic enzyme1 but without satisfactory evidence4 ,hydrocyanic acid1 even in dilute solution1 completely suspends the fermenting power of the juice1 without1 however1 producing any permanent change in the fermenting complex1 as is shown by the fact that when the hydrocyanic acid is removed by a current of air1 the juice regains its fermenting power4 ,in this respect hydrocyanic acid behaves precisely as with many other enzymes and with colloidal platinum ,bredig1 #aija4 ,sodium arsenite is a pronounced protoplasmic poison1 which rapidly destroys the power of growth and reproduction in living cells1 and was therefore applied to yeast-juice to differentiate between protoplasmic and enzymic action4 ,it was1 however1 found that the action of this substance was complicated by some unknown factor and very irregular results were obtained ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 pp4 #aic ff44 ,these phenomena appear to be of the same order as those produced by the addition of arsenates to yeast-juice ,harden and ,young1 #aijf1 #c1 and will be discussed along with the latter 7p4 #gg74 ,,permanent ,,preparations ,,containing ,,active ,,zymase4 ,a considerable number of preparations have been obtained in the dry state which retain some proportion of the fermenting power of yeast or yeast-juice4 ,starting with yeast-juice1 it is possible to arrive at this result either by evaporation or precipitation4 ,when the juice is very rapidly evaporated to a syrup at #bj to #be and then further dried at #ce1 either in the air or in a vacuum and finally exposed over sulphuric acid in a vacuum desiccator1 a dry brittle mass is obtained which is soluble in water and retains practically the whole of the fermenting power of the juice4 ,the success of the preparation depends on the nature of the yeast from which the juice is derived1 ,berlin yeasts ,v and ,s yielding much less satisfactory results than ,munich yeast4 ,the powder when p#jch thoroughly dry is found to retain its properties almost unimpaired for at least a year1 and can be heated to #he for eight hours without undergoing any serious loss of fermenting power ,buchner and ,rapp1 #ahih1 #d2 #aija2 ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 pp4 #acb-i4 ,active powders can also be obtained by precipitating yeast-juice with alcohol1 alcohol and ether1 or acetone4 ,the preparation is best effected by bringing the juice into #aj volumes of acetone1 centrifuging at once and as rapidly as possible1 washing1 first with acetone and then with ether1 and finally drying over sulphuric acid4 ,the white powder thus obtained is not completely soluble in water but is almost entirely dissolved by aqueous glycerol 7#be to #bj per cent471 forming a solution which has practically the same fermenting power as the original juice4 ,the precipitation can be repeated without any serious loss of fermenting power4 ,prolonged contact of the precipitate with the supernatant liquid1 especially when alcohol or alcohol and ether are used1 causes a rapid loss of the characteristic property ,albert and ,buchner1 #aijj1 #a1 #b2 ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 pp4 #bbh-bdf2 ,buchner and ,duchaek1 #aiji4 ,dry preparations capable of fermenting sugar can also be readily obtained from yeast without any preliminary rupture of the cells4 ,heat alone 7yielding a product known as hefanol7 or treatment with dehydrating agents may be used for this purpose1 and a brief allusion has already been made 7p4 #ba7 to the different varieties of permanent yeast 7,dauerhefe7 obtainable in these ways4 ,the most important of these products are the dried ,munich yeast 7,lebedeff1 see p4 #be71 and the material known as zymin1 which is now made under patent rights for medicinal purposes by ,schroder of ,munich4 ,the latter has proved of value in the investigation of the production of zymase in the yeast cell ,buchner and ,spitta1 #aijb1 and of many other problems concerned with alcoholic fermentation4 ,in order to prepare it #ejj grams of finely divided pressed brewer's yeast1 containing about #gj per cent4 of water1 are brought into #c litres of acetone1 stirred for ten minutes1 and filtered and drained at the pump4 ,the mass is then well mixed with #a litre of acetone for two minutes and again filtered and drained4 ,the residue is roughly powdered1 well kneaded with #bej c4c4 of ether for three minutes1 filtered1 drained1 and spread on filter paper or porous plates4 ,after standing for an hour in the air it is dried at #de for twenty-four hours4 ,about #aej grams of an almost white powder containing only #ee to #fe per cent4 of water are obtained4 ,this is quite incapable of growth or reproduction but produces a very considerable amount of alcoholic fermentation1 far greater indeed than a corresponding p#jci quantity of yeast-juice4 ,two grams of the powder corresponding to #f grams of yeast and about #ce to #d c4c4 of yeast-juice1 are capable of fermenting about #b grams of sugar1 whereas the #d c4c4 of yeast-juice would on the average only ferment from one-quarter to one-sixth of this amount of sugar4 ,the rate produced by this amount of zymin is about one-eighth of that given by the corresponding amount of living yeast ,albert1 #aijj2 ,albert1 ,buchner1 and ,rapp1 #aijb4 ,the proteoclastic ferment is still present in zymin1 which undergoes autolysis in presence of water in a similar manner to yeast-juice ,albert1 #aija1 #b4 ,as already mentioned an active juice can be prepared by grinding acetone-yeast with water1 sand1 and kieselguhr1 and this process presents the advantage that samples of yeast-juice of approximately constant composition can be prepared at intervals from successive portions of a uniform supply of acetone-yeast4 ,preparations of acetone-yeast1 made from yeast freed from glycogen by exposure in a thin layer to the air for three or four hours at #ce to #de1 or eight hours at the ordinary temperature ,buchner and ,mitscherlich1 #aijd1 show practically no autofermentation and may be used analytically for the estimation of fermentable sugars4 ,all the foregoing preparations exhibit the same general properties as yeast-juice1 as regards their behaviour towards the various sugars1 antiseptics1 etc4 ,when zymin is mixed with sugar solution without being previously ground1 it exhibits a peculiarity which is of some practical interest4 ,the time which elapses before the normal rate of fermentation is attained and the total fermentation obtainable vary with the amount of sugar solution added1 the time increasing and the total diminishing as the quantity of this increases4 ,this phenomenon appears to have been noticed by ,trommsdorff #aijb1 and a single experiment of ,buchner shows the influence of the same conditions ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 p4 #bfe1 ,nos4 #gjj-a4 ,harden and ,young have found that when #b grams of zymin are mixed with varying quantities of #aj per cent4 sugar solution the following results are obtained3-- ,volumes of ,total ,gas ,evolved in ,sugar #a #b #c #d #bbe hours4 ,solution #e c4c4 #aeg #caf #ddh #efe #bccc #aj #bb #aje #bc #cah #bjbc #bj #ji #bd #acf #bcg #abee #dj #ad #ag #bc #bi #efc p#jdj ,this behaviour appears to be due to the removal of soluble matter essential for fermentation from the cell1 which is discussed later on4 ,it follows that when zymin is being tested for fermenting power1 a uniform method should be adopted1 and all comparative tests should be made with the same volumes of added sugar solution4 ,ground zymin appears to begin to ferment somewhat more slowly than unground 7#b grm4 to #abd c4c4 of sugar solution in each case71 but eventually produces the same total volume of gas ,buchner and ,antoni1 #aije1 #a4 p#jda ,,chapter ,,iii4 ,,the ,,function ,,of ,,phosphates ,,in ,,alcoholic ,,fermentation4 ,in the course of some preliminary experiments 7commenced by the late ,allan ,macfadyen1 but subsequently abandoned7 on the production of anti-ferments by the injection of yeast-juice into animals1 the serum of the treated animals was tested for the presence of such antibodies both for the alcoholic and proteoclastic enzymes of yeast-juice1 and it was then observed that the serum of normal and of treated animals alike greatly diminished the autolysis of yeast-juice4 ,as the explanation of the comparatively rapid disappearance of the fermenting power from yeast-juice had been sought1 as already mentioned 7p4 #bj71 in the hydrolytic action of the tryptic enzyme which always accompanies zymase1 the experiment was made of carrying out the fermentation in the presence of serum1 with the result that about #fj to #hj per cent4 more sugar was fermented than in the absence of the serum ,harden1 #aijc4 ,this fact was the starting-point of a series of attempts to obtain a similar effect by different means1 in the course of which a boiled and filtered solution of autolysed yeast-juice was used1 in the hope that the products formed by the action of the tryptic enzyme on the proteins of the juice would1 in accordance with the general rule1 prove to be an effective inhibitant of that enzyme4 ,this solution was1 in fact1 found to produce a very marked increase in the total fermentation effected by yeast-juice1 the addition of a volume of boiled juice equal to that of the yeast-juice doubling the amount of carbon dioxide evolved ,harden and ,young1 #aije1 #a4 ,this effect was found to be common to the filtrates from boiled fresh yeast-juice and from boiled autolysed yeast-juice1 and was ultimately traced in the main1 not to the antitryptic effect which had been surmised1 but to two independent factors1 either of which was capable in some degree of bringing about the observed result4 ,boiled yeast-juice was indeed found to possess a decided anti-autolytic effect1 as determined by a comparison of the amounts of nitrogen rendered non-precipitable by tannic acid in yeast-juice alone p#jdb and in a mixture of yeast-juice and boiled juice on preservation ,harden1 #aije4 ,the anti-autolytic effect1 however1 appeared to vary independently of the effect on the fermentation1 and the conclusion was drawn1 as stated above1 that the increase in the alcoholic fermentation was not directly dependent on the decrease in the action of the proteoclastic enzyme but was due to some independent cause4 ,the property possessed by boiled yeast-juice of diminishing the autolysis of yeast-juice has now been carefully examined by ,buchner and ,haehn #aiaj1 #b and ascribed by them to a soluble antiprotease 7p4 #fe74 ,the two factors to which the increase in fermentation produced by the addition of boiled juice were ultimately traced were 7#a7 the presence of phosphates in the liquid1 and 7#b7 the existence in boiled fresh yeast-juice of a co-ferment or co-enzyme1 the presence of which is indispensable for fermentation ,harden and ,young1 #aije1 #a1 #b4 ,the former of these factors will be here discussed and the co-enzyme will form the subject of the following chapter4 ,the general fact that sodium phosphate increases the total fermentation produced by a given volume of yeast juice was observed on several occasions by ,wroblewski #aija and also by ,buchner ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 pp4 #ada-b1 who ascribed the action of this salt to its alkalinity1 comparing it in this respect with potassium carbonate and remarking that the increase in both cases took place chiefly in the first twenty hours of fermentation4 ,the increased amount of fermentation following the addition of boiled yeast-juice was also noted by ,buchner and ,rapp #ahii1 #b1 ,no4 #bfe1 p4 #bjic in a single experiment4 ,observations made at intervals of a few minutes instead of twenty hours have1 however1 revealed the fact that phosphates play a part of fundamental importance in alcoholic fermentation and that their presence is absolutely essential for the production of the phenomenon4 ,,effect ,,of ,,the ,,addition ,,of ,,phosphate ,,to ,a ,,fermenting ,,mixture ,,of ,,yeast-,,juice ,,and ,,sugar4 ,when a suitable quantity#b of a soluble phosphate is added to a fermenting mixture of glucose1 fructose1 or mannose with yeast-juice1 the rate of fermentation rapidly rises1 sometimes increasing as much as twenty-fold1 continues at this high value for a certain period and then falls again to a value approximately equal to1 but generally p#jdc somewhat higher than1 that which it originally had4 ,careful experiments have shown that during this period of enhanced fermentation the amounts of carbon dioxide and alcohol produced exceed those which would have been formed in the absence of added phosphate by a quantity exactly equivalent to the phosphate added in the ratio ,,co#b or ,c#b;,h#f,o3,r#b;,,hpo#d ,harden and ,young1 #aijf1 #a4 #b ,the effect of an excess of phosphate is discussed later on1 p4 #ga4 ,this result is of fundamental importance1 and the evidence on which it rests deserves some consideration4 ,quantitative experiments on this subject require certain preliminary precautions4 ,the acid phosphates are too acid to permit of any extended fermentation and the phosphates of the formula ,r#b;,,hpo#d absorb a considerable volume of carbon dioxide with production of a bicarbonate1 according to the reaction3-- ,r#b;,,hpo#d ,h#b;,,co#c ,,rhco#c ,,rh#b,,po#d4 ,the method which has been adopted1 therefore1 is to employ either a secondary phosphate saturated with carbon dioxide at the temperature of the experiment1 or a mixture of five molecular proportions of the secondary phosphate with one molecular proportion of a primary phosphate1 in which the amount of bicarbonate formed is negligible4 ,in the former case it is necessary to ascertain whether any of the carbon dioxide evolved is derived from the bicarbonate by the action of acid originally present or produced in the yeast-juice or by a disturbance of the original equilibrium owing to the chemical change which occurs4 ,this is done by acidifying duplicate samples with hydrochloric acid before and after the fermentation and measuring the gas evolved in each case4 ,any necessary correction can then be made4 ,the calculation of the extra amount of carbon dioxide evolved from yeast-juice containing sugar when a phosphate is added involves an estimation of the amount which would have been evolved in the absence of added phosphate1 and this is a matter of some difficulty4 ,since the final steady rate of fermentation attained is often slightly different from the initial rate1 the practice has been adopted of ascertaining this final rate and then calculating the total evolution corresponding to it for the whole period from the time of the addition of the phosphate to the end of the observations4 ,this amount deducted from the observed total leaves the extra amount of carbon dioxide formed1 and it is this quantity which is equivalent to the phosphate added4 ,alcohol is simultaneously produced in the normal ratio4 ,the justification for this method of calculation will be found later 7p4 #ed74 ,the following table1 containing the results of experiments with ,pg #jdd glucose1 fructose1 and mannose1 indicates very clearly the nature of the method of calculation and also of the agreement between observation and theory4 ,three quantities of #be c4c4 of yeast-juice #e c4c4 of a solution containing #a gram of the sugar to be examined 7a large excess7 were incubated with toluene at #be for one hour1 in order to remove all free phosphate1 and to each were then added #e c4c4 of a solution of sodium phosphate corresponding to #jafcb gram of ,mg#b,p#b,o#g and equivalent to #cbf c4c4 of carbon dioxide at ,n4,t4,p4 ,the rates of fermentation were then observed until they had passed through the period of acceleration and had fallen and attained a steady value1 the gases being measured moist at #aic and #gfjae mm4 ,glucose4 ,mannose4 ,fructose4 ,maximum rate attained1 c4cs4 per five minutes #if #g #aac ,final rate of fermentation #aa #jif #ajh ,total carbon dioxide produced by fermentation in fifty-five minutes after addition of phosphate #dig #dgh #dgf ,correction for evolution in absence of phosphate in fifty-five minutes #aba #ajf #aai ,extra carbon dioxide equivalent to phosphate #cgf #cgb #ceg at ,n4,t4,p4 #cdd #cd #cbf ,these numbers agree well with the value calculated from the phosphate added1 viz4 #cbf ,harden and ,young1 #aiji4 ,another experiment is illustrated graphically in ,fig4 #d1 in which the volume of carbon dioxide evolved is plotted against time4 ,the determination was in this case made by adding #be c4c4 of an aqueous solution containing #e grams of glucose to one quantity of #be c4c4 of yeast-juice 7curve ,a7 and #e c4c4 of #jc molar solution of the mixed primary and secondary sodium phosphates1 and #bj c4c4 of a solution containing #e grams of glucose to a second equal quantity of yeast-juice 7curve ,b74 ,curve ,a shows the normal course of fermentation of yeast-juice with glucose4 ,there is a slight preliminary acceleration during the first twenty minutes1 due to free phosphate in the juice1 and the rate then becomes steady at about #ad c4c4 in five minutes4 ,during this preliminary acceleration #aj c4c4 of extra carbon dioxide are evolved1 this number being obtained graphically by continuing the line of steady rate back to the axis of zero time4 ,curve ,b shows the effect of the added phosphate4 ,the rate rises to about #ie c4c4 in five minutes1 i4e4 to more than six times the normal rate1 and then gradually falls until after an hour it is again steady and almost exactly equal to #ad c4c4 per five minutes4 ,continuing the line of steady rate back to the axis of zero p#jde time it is found that the extra amount of carbon dioxide is #dh c4c4 ,subtracting from this the #aj c4c4 shown in curve ,a as due to the juice alone1 a difference of #ch c4c4 is obtained due to the added phosphate4 ,the amount calculated from the phosphate added in this case is1 at atmospheric temperature and pressure1 #chi c4c4 ,illustration3 ,,fig4 #d 7,graph of ,carbon ,dioxide ,evolution v ,time--,ed47 ,after the expiration of seventy minutes from the commencement of the experiment1 a second addition is made of an equal amount of phosphate4 ,the whole phenomenon then recurs1 as shown in curve ,c1 the maximum rate being slightly lower than before1 about #f c4c4 per five minutes1 and the rate again becoming finally steady at #ad c4c4 as before4 ,the extra amount of carbon dioxide evolved in this second period obtained graphically as in the former case1 is #ajg-fh #ci c4c4 ,it may be noted that in this case the observations after each addition last fifty to seventy minutes1 so that an error of #ja c4c4 per five minutes in the estimated final rate would make an error of #a to #ad c4c4 in the extra amount of carbon dioxide1 i4e4 about #c to #d per cent4 of the total1 and this is approximately the limit of accuracy of the method4 p#jdf ,the results are more precise when the yeast-juice employed is an active one1 since1 when the fermenting power of the juice is low1 the initial period of accelerated fermentation is unduly prolonged and the calculation of the extra amount of carbon dioxide is rendered uncertain4 ,zymin 7p4 #ch7 yields precisely similar results to yeast-juice1 but in this case the rate of fermentation is not so largely increased4 ,this has the effect that the extra amount of carbon dioxide cannot be quite so accurately estimated for zymin1 because a slight error in the determination of the final rate of fermentation has a greater influence on the result4 ,the equivalence between the extra amount of carbon dioxide evolved and the phosphate added is1 however1 unmistakable1 as is shown by the following results of an experiment with zymin1 in which #f grams of zymin 7,schroder7 #c grams of fructose 7,schering7 #be c4c4 of water were incubated at #be in presence of toluene until a steady rate had been attained4 ,five c4c4 of a solution of sodium phosphate equivalent to #cbb c4c4 carbon dioxide at ,n4,t4,p4 were then added4 ,maximum rate attained1 c4c4 per five minutes #ada ,final rate of fermentation #fb ,total evolved by fermentation in eighty minutes after addition of phosphate #aca ,correction for evolution in absence of phosphate in eighty minutes #iib ,extra carbon dioxide at #af and #gfga mm #cah ,n4,t4,p #bih ,considering the small proportional rise in rate and the long period of accelerated fermentation1 the agreement between the volume observed1 #bih c4c41 and that calculated from the phosphate1 #cbb1 is quite satisfactory ,harden and ,young1 #aiaj1 #a4 ,precisely the same relations hold for maceration extract1 but in this case it must be remembered that a large amount of free phosphate is present in the extract1 as much as #jcabi grm4 ,mg#b,p#b,o#g being obtained from #bj c4c4 in one preparation1 so that the original extract had the concentration of a #jad molar solution of sodium phosphate4 ,it is in fact not improbable that the delay in the onset of fermentation sometimes observed with maceration extract 7see ,lebedeff1 #aiab1 #b2 ,neuberg and ,rosenthal1 #aiac7 may be due to the presence of phosphate in so great an excess of the amount which can be rapidly esterified by the enzymes that the rate of fermentation is at first greatly lowered 7see p4 #ga74 ,when this phosphate is removed by incubation with glucose or fructose1 the subsequent addition of phosphate produces the characteristic action and the extra carbon dioxide evolved is1 as with other yeast preparations1 equivalent to the phosphate added4 ,an actual estimation carried out in this way gave #ce c4c4 of ,,co#b for an addition of phosphate equivalent to #cbi c4c4 ,harden and ,young1 #aiab4 p#jdg ,within the limits imposed by the experimental conditions1 then1 the fact is well established that the addition of a soluble phosphate to a fermenting mixture of a hexose with yeast-juice1 maceration extract1 dried yeast1 or zymin causes the production of an equivalent amount of carbon dioxide and alcohol4 ,this fact indicates that a definite chemical reaction occurs in which sugar and phosphate are concerned1 and this conclusion is confirmed when the fate of the added phosphate is investigated4 ,if an experiment1 such as one of those described above1 be interrupted as soon as the rate of fermentation has again become normal1 and the liquid be boiled and filtered1 it is found that nearly the whole of the phosphorus present passes into the filtrate1 but that only a small proportion of this exists as mineral phosphate1 whilst the remainder1 including that added in the form of a soluble phosphate1 is no longer precipitable by magnesium citrate mixture ,harden and ,young1 #aije1 #b4 ,a similar observation was made at a later date by ,iwanoff #aijg1 who had previously observed #aije that living yeast1 like many other vegetable organisms1 converted mineral phosphates into organic derivatives4 ,iwanoff employed zymin and hefanol 7p4 #ch7 instead of yeast-juice1 and found that phosphates were thereby rendered non-precipitable by uranium acetate solution1 but did not observe the accelerated fermentation caused by their addition4 ,the foregoing conclusions have been strikingly confirmed by experiments with maceration extract carried out by ,euler and ,johansson #aiac1 in which both the carbon dioxide evolved and the phosphate rendered non-precipitable by magnesia were determined at intervals4 ,when dried yeast is employed as the fermenting agent1 the amount of phosphate esterified in the earlier stages is greater than would be expected1 but ultimately becomes exactly equivalent to the carbon dioxide evolved4 ,,nature ,,of ,,the ,,phospho-,,organic ,,compound ,,formed ,,by ,,yeast-,,juice ,,and ,,zymin ,,from ,,the ,,hexoses ,,and ,,phosphate4 ,the formation and properties of the compound produced from phosphates in the manner just described have been investigated by ,harden and ,young #aije1 #b2 #aijh1 #a2 #aiji2 #aiaa1 #b1 ,young #aiji2 #aiaa1 ,iwanoff #aijg2 #aiji1 #a1 ,lebedeff #aiji2 #aiaj2 #aiaa1 #e1 #f2 #aiab1 #c2 #aiac1 #a2 and ,euler #aiab1 #a2 ,euler and ,fodor1 #aiaa2 ,euler and ,kullberg1 #aiaa1 #c2 ,euler and ,ohlsn1 #aiaa2 #aiab2 ,euler and ,johansson1 #aiab1 #d2 ,euler and ,bckstrm1 #aiab1 but its exact constitution cannot as yet be regarded as definitely known4 p#jdh ,phosphates undergo this characteristic change when the sugar undergoing fermentation is glucose1 mannose1 or fructose1 and it may be said at once that no distinction can be established between the products formed from these various hexoses2 they all appear to be identical4 ,the compound produced is1 as already mentioned1 not precipitated by ammoniacal magnesium citrate mixture1 nor by uranium acetate solution4 ,it can1 however1 be precipitated by copper acetate 7,iwanoff7 and by lead acetate 7,young74 ,the preparation of the pure lead salt from the liquid obtained by fermenting a sugar with yeast-juice or zymin in presence of phosphate is commenced by boiling and filtering the liquid4 ,magnesium nitrate solution and a small quantity of caustic soda solution are then added to precipitate any free phosphate1 and the liquid well stirred and allowed to stand over night4 ,to the neutralised filtrate lead acetate is then added together with sufficient caustic soda solution to maintain the reaction neutral to litmus1 until no further precipitate is formed4 ,the liquid is then filtered or1 better1 centrifugalised1 and the precipitate repeatedly washed with water until a portion of the clear filtrate gives no reduction when boiled with ,fehling's solution4 ,it is essential that this washing should be thorough as evidence has recently been obtained of the formation under certain conditions of a hexosephosphate1 the lead salt of which is not so sparingly soluble as that of the hexosediphosphate ,harden and ,robison1 #aiad4 ,the lead precipitate is then suspended in water1 decomposed by a current of sulphuretted hydrogen1 the clear filtrate freed from sulphuretted hydrogen by a current of air1 and finally neutralised with caustic soda4 ,the removal of phosphate and conversion into lead salt are repeated twice1 and the resulting lead salt is then found to be free from nitrogen and to have a composition represented by the formula ,c#f;,h#aj,o#d7,,po#d,pb7#b4 ,lebedeff carries out the preparation in a somewhat different manner4 ,the fermentation is effected by means of air-dried yeast 7#aej grams to #a litre of water1 #baj grams cane-sugar and #aje grams of a mixture of #b parts ,na#b;,,hpo#d and #a part ,na,h#b,,po#d7 and the liquid 7about #gjj c4c47 after boiling and filtering1 is treated with an equal volume of acetone4 ,about #cjj c4c4 of a thick liquid is precipitated and this is redissolved in water and precipitated by an equal volume of acetone two or three times4 ,the final liquid is then precipitated with warm lead acetate solution and filtered and washed with dilute lead acetate solution until the filtrate is clear and no longer reduces ,fehling's solution after removal of the lead #aiaj4 ,euler and ,fodor #aiaa on the other hand precipitate the free phosphate with magnesia mixture and then add acetone1 dissolve the syrup thus precipitated in water and add copper p#jdi acetate solution4 ,a blue copper salt is precipitated which is thoroughly washed with water and used for the preparation of solutions of the acid4 ,a solution of the free acid can readily be prepared by the action of sulphuretted hydrogen on the lead salt suspended in water4 ,it forms a strongly acid liquid1 which requires exactly two equivalents of base for each atom of phosphorus present to render it neutral to phenolphthalein4 ,it decomposes when evaporated1 leaving a charred mass containing free phosphoric acid4 ,the acid is slightly optically active1 and has _/a_/,d #cd4 ,a number of amorphous salts have been prepared by precipitation from a solution of the sodium salt1 and of these the silver1 barium1 and calcium salts have been analysed with results agreeing with the general formula ,c#f;,h#aj,o#d7,,po#d,r#b7b4 ,the magnesium1 calcium1 barium1 and manganese salts1 which are only sparingly soluble1 are all precipitated when their solutions are boiled but re-dissolve on cooling1 and this property can be utilised for their purification4 ,the alkali salts have only been obtained as viscid residues4 ,a difference of opinion exists as to the molecular weight and constitution of this substance4 ,iwanoff #aiji1 #a regards it as a triosephosphoric acid1 ,c#c;,h#e,o#b7,,po#d;,h#b71 basing this view on the preparation of an osazone which melted at #adb1 but when recrystallised from benzene gave a product melting at #abg-h1 which had the same appearance1 melting-point1 and nitrogen content as the triosazone formed by the action of phenylhydrazine on the oxidation products of glycerol4 ,neither ,lebedeff #aiji nor ,young could obtain ,iwanoff's osazone1 and all attempts to reduce the acid with formation of glycerol either by sodium amalgam or hydriodic acid were unsuccessful 7,young74 ,there is therefore practically no serious experimental evidence in favour of ,iwanoff's view4 ,on the other hand1 ,harden and ,young regard the acid as a diphosphoric ester of a hexose4 ,this view is based on the fact that when the acid is boiled with water1 or an acid1 free phosphoric acid is produced along with a levo-rotatory solution containing fructose and possibly a small proportion of some other sugar or sugars4 7,euler and ,fodor however did not obtain a hexose in this way #aiaa47 ,the acid itself only reduces ,fehling's solution after some hours in the cold1 rapidly when boiled1 whereas when its solution is first boiled1 and then treated with ,fehling's solution in the cold1 the products of decomposition bring about reduction in a few minutes4 ,the reduction brought about when the acid is boiled with ,fehling's solution is considerably less 7#cc per cent47 than that produced by an equivalent amount of glucose4 ,the behaviour of the compound towards phenylhydrazine is also in complete agreement p#jej with this view4 ,lebedeff found #aiji1 #aiaj that the acid or its salts heated with phenylhydrazine in presence of acetic acid gave an insoluble compound which was ultimately found to be the _/phenylhydrazine salt of hexosemonophosphoric acid osazone_/ ,c#f;,h#e,,nh,,nh#b;,h#b,,po#d;,c#d;,h#e 7,,oh7#c ,c7,n#b;,,hc#f;,h#e7;,,ch7,n#b;,,hc#f;,h #e7 ,lebedeff1 #aiaj2 #aiaa1 #f2 ,young1 #aiaa4 ,after recrystallisation from alcohol this compound forms yellow needles1 melting at #aea-aeb4 ,it is decomposed by caustic soda yielding a _/sodium salt_/ ,na#b,,po#d;,c#d;,h#e7,,oh7#c7;,,cn#b;,, hc#f;,h#e7;,,ch7,n#b;,,hc#f;,h#e7 and on boiling with caustic soda decomposes giving a hexosazone 7free from phosphorus7 which is probably glucosazone1 and in addition glyoxalosazone1 probably as the result of a secondary decomposition4 ,towards acids it is remarkably stable yielding with hydrochloric acid a _/hexosonephosphoric ester_/ from which the original osazone can be regenerated 7,lebedeff74 ,lebedeff at first #aiaj argued from the formation of this osazone that the original hexosephosphate contained only one phosphoric acid group per molecule of hexose4 ,it was however shown by ,young #aiaa and subsequently confirmed by ,lebedeff #aiaa1 #f that one molecule of phosphoric acid is split off during the formation of the osazone1 even in neutral solution4 ,moreover it has been found that in the cold hexosediphosphoric acid reacts with #c molecules of phenylhydrazine forming the _/diphenylhydrazine salt of hexosediphosphoric acid phenylhydrazone_/ 7,c#f;,h#e,,nh,,nh#b;,h#b,,po#d7b;,c#f;, h#g7,,oh7#c,n#b;,,hc#f;,h#e4 ,this compound crystallises out when #a volume of alcohol is added to a solution of #c molecules of phenylhydrazine in one of the acid and forms colourless needles melting at #aae-aag4 p-,bromophenylhydrazine yields an analogous compound melting at #abg-abh4 ,precisely the same products are given with phenylhydrazine by the hexosephosphoric acid prepared from glucose1 mannose1 and fructose1 proving that all these sugars yield the same hexosediphosphoric acid1 a point of fundamental importance4 ,direct measurements of the molecular weight of the acid by the freezing-point method1 combined with the determination of the degree of dissociation by the rate of cane-sugar inversion1 are indecisive1 but indicate that the acid has a molecular weight considerably higher than that required for a triosephosphoric acid4 ,a similar uncertainty attaches to the determination of the molecular weight from the freezing-point depression and conductivity of the acid potassium salt ,euler and ,fodor1 #aiaa4 ,euler however concludes p#jea that both a hexosediphosphoric acid and a triosemonophosphoric acid are formed1 but has not prepared any derivatives of the latter4 ,as regards the constitution of the hexosephosphoric ester several suggestions have been made by ,young1 but no decisive evidence at present exists4 ,the identity of the products from glucose1 mannose1 and fructose may be explained by regarding the acid as a derivative of the enolic form common to these three sugars 7p4 #ig71 or by supposing that portions of two sugar molecules may be concerned in its production4 ,the formation and composition of the hydrazone and osazone are of great importance as they indicate that in all probability one of the phosphoric acid residues is united with the carbon atom adjacent to the carbonyl group of the hexose4 ,they moreover render it certain that the original phosphoric ester is a hexosediphosphoric ester and not a triosemonophosphoric ester4 ,hexosediphosphoric acid has not as yet been discovered in the animal body4 ,the action of a number of enzymes upon it has been examined ,euler1 #aiab1 #b2 ,euler and ,funke1 #aiab2 ,harding1 #aiab2 ,plimmer1 #aiac with the following results4 ,the lipase of castor oil seeds1 a glycerol extract of the intestinal mucous membrane of the rabbit and pig1 and an aqueous extract of bran have a slow hydrolytic action1 whereas pepsin and trypsin are without effect4 ,feeding experiments with rabbits and dogs indicate that the ester is capable of hydrolysis in the animal body1 a large proportion of the phosphorus being excreted as inorganic phosphate4 ,the ester is also decomposed by _/,bacillus coli communis_/4 ,it is remarkable that the hexosephosphate is not fermented nor hydrolysed by living yeast1 a fact observed by ,iwanoff1 ,harden and ,young1 and ,euler1 although1 according to the experiments of ,paine #aiaa1 the yeast cell is at all events partially permeable to the sodium salt4 ,,the ,,equation ,,of ,,alcoholic ,,fermentation4 ,an equation can readily be constructed for the reaction in which hexosephosphate is formed1 the data available being the formula of the product and the relation between the phosphate added and the carbon dioxide and alcohol produced3-- 7#a7 #b;,c#f;,h#ab,o#f #b,,po#d;,,hr#c #b;,,co#b #b;,c#b;,h#f,o #b;,h#b,o ,c#f;,h#aj,o#d7,,po#d,r#b7b4 ,according to this1 two molecules of sugar are concerned in the change1 the carbon dioxide and alcohol being equal in weight to one p#jeb half of the sugar used1 and the hexosephosphate and water representing the other half4 ,additional confirmation of this equation is afforded by the determination of the ratio between sugar used and carbon dioxide evolved when a known weight of sugar together with an excess of phosphate is added to yeast-juice at #be4 ,the phenomena then observed are precisely similar to those which occur when a phosphate is added to a fermenting mixture of yeast-juice and excess of sugar as described above4 ,the rate of fermentation rapidly rises and then gradually falls until a rate is attained approximately equal to that of the autofermentation of the juice in presence of phosphate4 ,at this point it is found that the extra amount of carbon dioxide evolved1 beyond that which would have been given off in the absence of added sugar1 bears the ratio expressed in equation 7#a7 to the sugar added ,harden and ,young1 #aiaj1 #b4 ,the results of four estimations made in this way were 7_/a_/7 #jb grams of glucose gave #bfe and #bgi c4c4 of carbon dioxide at ,n4,t4,p42 7_/b_/7 #jb grams of fructose gave #bgi and #bhi c4c4 ,the carbon dioxide calculated from the sugar added in each of the four cases is #bfif c4c4 ,it has also been shown by ,euler and ,johansson #aiac that in the fermentation of a mixture of equivalent amounts of phosphate and glucose1 the whole of the glucose had disappeared when the whole of the phosphate had become esterified4 ,,cycle ,,of ,,changes ,,undergone ,,by ,,phosphate ,,in ,,alcoholic ,,fermentation4 ,according to equation 7#a7 the free phosphate present is used up in the reaction1 and the question at once arises whether there is any source from which a constant supply of free phosphate can be elaborated in the juice1 or whether some other change occurs which results in the formation of carbon dioxide and alcohol in the absence of free phosphate4 ,the experimental evidence points in the direction of the former of these alternatives1 but the question is a very difficult one to decide with absolute certainty4 ,when a mixture of a phosphate with yeast-juice and sugar is examined at intervals and the amount of free phosphate estimated1 the following stages are observed3-- #a4 ,during the initial period of accelerated fermentation following the addition of the phosphate1 the concentration of free phosphate rapidly diminishes4 #b4 ,at the close of this period1 the amount of free phosphate p#jec present is very low1 and1 as long as active fermentation continues1 no marked increase in it occurs4 #c4 ,as alcoholic fermentation slackens and finally ceases1 a marked and rapid rise in the amount of free phosphate occurs at the expense of the hexosephosphate1 which steadily diminishes in amount1 and this change is brought about by an enzyme in the juice and ceases if the liquid be boiled4 ,this last reaction may be represented by the equation 7#b7 ,c#f;,h#aj,o#d7,,po#d,r#b7b #b;,h#b,o ,c#f;,h#ab,o#f #b,,po#d;,,hr#b4 ,in the light of this equation1 together with equation ,no4 #a1 given above1 all these facts can be simply and easily understood4 ,the rapid diminution in the amount of free phosphate during stage #a corresponds with the occurrence of reaction 7#a74 ,during the whole period of fermentation the enzymic hydrolysis of the hexosephosphate is proceeding according to equation 7#b74 ,up to the end of stage #b the phosphate thus produced enters into reaction1 according to equation 7#a71 with the sugar which is present in excess and is thus reconverted into hexosephosphate1 so that as long as alcoholic fermentation is proceeding freely1 no accumulation of free phosphate can occur4 ,as soon as alcoholic fermentation ceases1 however1 it is no longer possible for the phosphate to pass back into hexosephosphate1 and hence it accumulates in the free state4 ,a similar hydrolysis of hexosephosphate and accumulation of phosphate occur when a solution of hexosephosphate is treated with yeast-juice which has been deprived of the power of fermentation by dialysis1 or with zymin freed from co-enzyme by washing 7p4 #fc74 ,the actual rate of fermentation observed in any particular case in presence of excess of sugar1 enzyme1 and co-enzyme must on this view depend on the supply of phosphate which is available4 ,in presence of an adequate amount of phosphate1 as well as of sugar1 the highest rate attained represents the maximum velocity at which reaction 7#a7 can proceed in that sample of yeast-juice or zymin1 and this high rate is characteristic of the initial period of accelerated fermentation which follows the addition of a suitable quantity of phosphate4 ,by the simple expedient of renewing the supply of phosphate as rapidly as it is converted into hexosephosphate1 this high rate can be maintained for a considerable time ,harden and ,young1 #aijh1 #a4 ,in this way1 for example1 an average rate of evolution of carbon dioxide of #ae c4c4 in five minutes was maintained for an hour and a p#jed quarter1 whereas the normal rate in the absence of added phosphate was #c c4c4 ,as soon as all the free phosphate has entered into the reaction1 however1 the supply of phosphate depends in the main on the rate at which the resulting hexosephosphate is decomposed1 and the rate of fermentation now attained is conditioned by the rate at which reaction 7#b7 proceeds1 and this evidently depends on the existing concentration of the hydrolytic enzyme1 which may be provisionally termed _/hexosephosphatase_/4 ,the rates attained during the initial period of rapid fermentation and the subsequent period of slow fermentation are thus seen to represent the velocities of two entirely different chemical reactions4 ,these considerations also explain why it is the _/extra_/ carbon dioxide evolved during the initial period1 and not the total carbon dioxide1 which is equivalent to the added phosphate4 ,as the production of phosphate is proceeding throughout the whole period at a rate which is equivalent to the normal rate of fermentation1 it is obviously necessary to deduct the corresponding amount of carbon dioxide from the total evolved in order to ascertain the amount equivalent to the added phosphate4 ,an explanation is also afforded of the fact that a considerable increase in the concentration of hexosephosphate does not materially increase the normal rate of fermentation4 ,this is probably due to the circumstance that1 in accordance with the general behaviour of enzymes in presence of excess of the fermentable substance1 the hexosephosphatase hydrolyses approximately equal amounts of hexosephosphate in equal times whatever the concentration of the latter may be1 above a certain limit4 ,according to the experiments of ,euler and ,johansson #aiac the hydrolytic activity of the hexosephosphatase is greatly diminished by the presence of toluene4 ,,effect ,,of ,,phosphate ,,on ,,the ,,total ,,fermentation ,,produced ,,by ,,yeast-,,juice4 ,the addition of a phosphate to yeast-juice not only produces the effect already described1 but also enables a given volume of yeast-juice to effect a larger total fermentation1 even after allowance is made for the carbon dioxide equivalent to the quantity of phosphate added4 ,the increase in the case of ordinary yeast-juice has been found to amount to from #aj to #aej per cent4 of the original total fermentation p#jee produced by the juice in the absence of added phosphate4 ,the numbers contained in columns #a and #b of the table on p4 #ef illustrate this effect1 the ratio of the total in the presence of phosphate to that obtained in its absence being given1 as well as that of the total in presence of phosphate less the equivalent of the phosphate added1 to the original fermentation4 ,the cause of this increase in the total fermentation is probably to be sought mainly in a protective action of the excess of hexosephosphate on the various enzymes1 for1 as has been stated above1 the rate of fermentation after the termination of the initial period1 is practically the same as in the absence of added phosphate 7see p4 #dc74 ,now it follows from equation 7#a7 7p4 #ea7 that in the total absence of phosphate no fermentation should occur1 and the experimental realisation of this result would afford very strong evidence in favour of this interpretation of the phenomenon4 ,hitherto1 however1 it has not been found possible to free the materials employed completely from phosphorus compounds which yield phosphates by enzymic hydrolysis during the experiment1 but it has been found that when the phosphate contents are reduced to as low a limit as possible1 the amount of sugar fermented becomes correspondingly small1 and1 further1 that in these circumstances the addition of a small amount of phosphate or hexosephosphate produces a relatively large increase in the fermenting power of the enzyme4 ,when the total phosphorus present is thus largely reduced1 the increase produced by the addition of a small amount of phosphate may amount to as much as eighty-eight times the original1 in addition to the quantity equivalent to the phosphate1 whilst the actual total evolved1 including this equivalent1 may be as much as twenty times the original fermentation4 ,this result must be regarded as strong evidence in favour of the view that phosphates are indispensable for alcoholic fermentation4 ,the results indicated above were experimentally obtained in three different ways and are exhibited in the following table4 ,in the first place 7cols4 #c and #d71 advantage was taken of the fact that the residues obtained by filtering yeast-juice through a ,martin gelatin filter 7p4 #ei7 are sometimes found to be almost free from mineral phosphates1 whilst they still contain a small amount of co-enzyme4 ,the experiment then consists in comparing the fermentation produced by such a residue poor in phosphate with that observed when a small amount of phosphate is added4 ,the second method 7col4 #e7 consisted in carrying out two parallel fermentations by means of a residue rendered inactive by filtration p#jef and a solution of co-enzyme free from phosphate and hexosephosphate 7p4 #fg7 ,harden and ,young1 #aiaj1 #b4 ,the third method 7col4 #f7 consisted in washing zymin with water1 to remove soluble phosphates1 and then adding to it a solution of co-enzyme containing only a small amount of phosphate1 and ascertaining the effect of the addition of a small known amount of hexosephosphate upon the fermentation produced by this mixture ,harden and ,young1 #aiaa1 #a4 #a #b #c #d #e #f c4c4 c4c4 c4c4 c4c4 c4c c4c4 ,gas evolved in absence of added phosphate #cfi #bbj #ad #ab #bjc #ae ,in the presence of #fbi #fbi #beh #bfh #ibc #acbg ,increase due to phosphate #bfj #dji #bdd #bef #gbj #acab ,carbonic acid equivalent to phosphate #fc #fa #afi #afh #afh -- ,increase after initial period #aig #cdh #ge #hh #eeb -- ,ratio of totals #ag #bi #ahd #bac #de #hh ,ratio of increase after initial period to original fermentation #je #af #ec #gc #bg -- ,,production ,,of ,a ,,fermentable ,,sugar ,,from ,,hexosephosphate ,,by ,,the ,,action ,,of ,,an ,,enzyme ,,contained ,,in ,,yeast-,,juice4 ,the sugar which1 according to equation 7#b7 accompanies the phosphate formed by the enzymic hydrolysis of hexosephosphate is under ordinary circumstances fermented by the alcoholic enzyme of the juice and thus escapes detection4 ,when1 however1 a solution of a hexosephosphate is exposed to the action of either yeast-juice or zymin1 entirely or partially freed from co-enzyme1 this sugar1 being no longer fermented1 accumulates and can be examined4 ,it has thus been found ,harden and ,young1 #aiaj1 #b that a sugar is in fact produced in this way which can be fermented by living yeast and exhibits the reactions of fructose1 although the presence of other hexoses is not excluded4 ,the products of the enzymic hydrolysis of the hexosephosphates therefore appear to be the same as1 or similar to1 those formed by the action of acids ,young1 #aiji4 ,a further consequence of these facts is that a hexosephosphate will yield carbon dioxide and alcohol when it is added to yeast-juice or zymin1 and this has also been found to be the case ,harden and ,young1 #aiaj1 #b2 ,iwanoff1 #aiji1 #a4 p#jeg ,,mechanism ,,of ,,the ,,formation ,,of ,,hexosediphosphoric ,,acid4 ,on this subject little is yet known1 but a number of extremely interesting results1 the interpretation of which is still doubtful1 have been obtained by ,euler and his colleagues4 ,euler has obtained a yeast ,yeast ,h of the ,st4 ,erik's brewery in ,stockholm which differs from ,munich yeast in several respects4 ,a maceration extract prepared from the yeast dried at #dj in a vacuum produces no effect on a glucose solution containing phosphate4 ,if1 however1 the glucose solution be previously partially fermented with living yeast and then boiled and filtered1 the addition of the extract prepared from ,yeast ,h brings about the esterification of phosphoric acid without any accompanying evolution of carbon dioxide ,euler and ,ohlsn1 #aiaa1 #aiab4 ,euler interprets this as follows3 7_/a_/7 ,glucose itself is not directly esterified1 but must first undergo some preliminary change1 which is brought about by the action of living yeast4 ,no proof of the existence of a new modification of glucose in this solution has however been advanced1 other than its behaviour to extract of ,yeast ,h1 so that ,euler's conclusion cannot be unreservedly accepted4 ,it is moreover possible and even more probable that some thermostable catalytic substance 7perhaps a co-enzyme7 passes from the yeast into the glucose solution and enables the yeast extract to attack the glucose and phosphoric acid4 ,a very small degree of esterification was also produced when an extract having no action on glucose and phosphate was added to glucose which had been treated with #b per cent4 caustic soda for forty hours1 but the nature of the compound formed was not ascertained ,euler and ,johansson1 #aiab1 #d4 7_/b_/7 ,the esterification of phosphoric acid without the evolution of carbon dioxide implies that the enzyme by which this process is effected is distinct from that which causes the actual decomposition of the sugar4 ,euler goes further than this and regards the enzyme as a purely synthetic one1 giving it the name of hexosephosphatese to distinguish it from the hexosephosphatase which hydrolyses the hexosephosphate4 ,the evidence on which this conclusion is based cannot be regarded as satisfactory1 inasmuch as it consists in the observation that _/in presence of sugar_/ yeast extract does not hydrolyse the phosphoric ester4 ,this1 however1 could not be expected since hydrolysis and synthesis under these conditions would ultimately proceed at equal rates4 ,in any case the adoption of this nomenclature is inconsistent with the conception of an enzyme as a catalyst and is therefore inadvisable until the reaction has been much more thoroughly studied4 p#jeh ,it may further be pointed out that no proof has yet been advanced that the phosphoric ester produced without evolution of carbon dioxide is identical with hexosediphosphoric acid produced with evolution of carbon dioxide4 ,it is by no means improbable that it represents some intermediate stage in the production of the latter 7see p4 #aag74 ,euler's other results on this subject may be briefly summarised as follows3-- 7#a7 ,in presence of excess of sugar the esterification of the phosphoric acid proceeds by a monomolecular reaction and is most rapid in faintly alkaline reaction ,euler and ,kullberg1 #aiaa1 #c4 7#b7 ,when yeast extract has been heated for #cj minutes to #dj it effects the esterification of phosphoric acid at a much greater rate than the unheated extract 7#b-aj times74 ,heating at #ej for #cj minutes however completely inactivates the extract4 ,the cause of the activation is as yet unknown4 ,the temperature coefficient for the unheated extract 7#age-cj7 is #ad-ae for #aj rise of temperature ,euler and ,ohlsn1 #aiaa4 7#c7 ,yeasts which in the dried state all produce rapid esterification of phosphoric acid1 yield extracts of very unequal powers in this respect ,euler1 #aiab1 #a4 p#jei ,,chapter ,,iv4 ,,the ,,co-,,enzyme ,,of ,,yeast-,,juice4 ,in the previous chapter reference was made to the fact that the addition of boiled yeast-juice greatly increases the amounts of carbon dioxide and alcohol formed from sugar by the action of a given volume of yeast-juice4 ,when the boiled juice is dialysed the substance or substances to which this effect is due pass into the dialysate1 the residue being quite inactive4 ,in order to ascertain the effect on the process of alcoholic fermentation of the complete removal of these unknown substances from yeast-juice itself1 dialysis experiments were instituted with fresh yeast-juice1 capable of bringing about an active production of carbon dioxide and alcohol from sugar4 ,it was already known from the experiments of ,buchner and ,rapp #ahih1 #a that dialysis in parchment paper for seventeen hours at #j against water or physiological salt solution only produced a diminution of about #bj per cent4 in the total amount of fermentation obtainable1 and in view of the less permanent character of the juice from top yeasts a more rapid method of dialysis was sought4 ,this was found in the process of filtration under pressure through a film of gelatin1 supported in the pores of a ,chamberland filter candle1 which had been introduced by ,martin #ahif4 ,in this way it was found possible to divide the juice into a residue and a filtrate1 each of which was itself incapable of setting up the alcoholic fermentation of glucose1 whereas1 when they were reunited1 the mixture produced almost as active a fermentation as the original juice ,harden and ,young1 #aije1 #a2 #aijf1 #b4 ,the apparatus employed for this purpose consists of a brass tube provided with a flange in which the gelatinised candle is held by a compressed india-rubber ring1 and is shown in section in ,fig4 #e4 ,two such apparatus are used1 each capable of holding about #gj c4c4 of the liquid to be filtered4 ,the tubes1 after being filled with the yeast-juice1 are connected by means of a screw joint with a cylinder of compressed air and the filtration carried out under a pressure of #ej atmospheres1 p#jfj the arrangement employed being shown in ,fig4 #f4 ,in the earlier experiments #be to #ej c4c4 of yeast-juice were placed in each tube and the filtration continued until no more liquid passed through4 ,the residue was then washed several times _/in situ_/ by adding water and forcing it through the candle4 ,the time occupied in this process varied from six to twelve hours with different preparations of yeast-juice4 ,the candle was then removed from the brass casing and the thick1 brown-coloured residue scraped off1 dissolved in water1 and at once examined4 ,it was subsequently found to be possible to dry this residue _/in vacuo_/ over sulphuric acid without seriously altering the fermenting power1 and this led to a slight modification of the method1 which is now conducted as follows4 ,two quantities of #ej c4c4 each of yeast-juice are filtered1 without washing1 and the residues spread on watch-glasses and dried _/in vacuo_/4 ,two fresh quantities of #ej c4c4 are then filtered through the same candles and the residues also dried4 ,the #bjj c4c4 of juice treated in this way give a dry residue of #ag to #bd grams4 ,the residue is then dissolved in #ajj c4c4 of water and filtered in quantities of #ej c4c4 through two fresh gelatinised candles and the residue again dried4 ,a considerable diminution in weight occurs1 partly owing to incomplete removal from the candle and brass casing1 and the final residue only amounts to about #i to #ab grams4 ,occasionally it is necessary to repeat the processes of dissolving in water1 filtering1 and drying1 but a considerable loss both of material and fermenting power attends each such operation4 ,illustration ,,fig4 #e4 7,filter ,apparatus1 ,tube_/,flange ,detail--,ed47 ,the sticky residue dries up very rapidly _/in vacuo_/ to a brittle1 scaly mass1 which is converted by grinding into a light yellow powder4 ,the filtrate was invariably found to be quite devoid of fermenting power1 none of the enzyme passing through the gelatin4 ,illustration3 ,,fig4 #f4 7,filter ,apparatus--,ed47 _/,properties of the ,filtered and ,washed ,residue4_/--,the residue prepared as described above consists mainly of the protein1 glycogen1 and dextrins of the yeast-juice1 and is almost free from mineral phosphates1 but contains a certain amount of combined phosphorus4 ,it also contains the enzymes of the juice1 including the proteoclastic enzyme1 and the hexosephosphatase 7p4 #ed74 ,its solution in water is usually quite inactive to glucose or fructose1 but in some cases produces a small and evanescent fermentation4 ,when the original filtrate or a corresponding p#jfa quantity of the filtrate from boiled fresh yeast-juice is added1 the mixture ferments glucose or fructose quite readily4 ,the following table shows the quantitative relations observed1 the sugar being in all cases present in excess3-- ,filtrate ,boiled ,water ,,co#b ,no4 ,material4 ,volume4 added4 ,juice added4 evolved4 added4 c4c4 c4c4 c4c4 #a ,undried and unwashed residue #ae c4c4 #j #j #ae #j g4 #ae #ae #j #j #jjce #b #ae #j #j #ae #jjbd #ae #j #ae #j #jbhb #c ,undried and washed residue #be #j #j #j #jd c4c4 #be #j #be #j #bfh #d #bj #j #j #j #hc #bj #bj #j #j #ijc #e ,washed and dried residue #a gram in #ae c4c4 #j #j #j #j #j #ab #j #ajh #f #a gram in #be c4c4 #j #j #j #j #j #be #j #cfd p#jfb ,these experiments lead to the conclusion that the fermentation of glucose and fructose by yeast-juice is dependent upon the presence1 not only of the enzyme1 but also of another substance which is dialysable and thermostable4 ,precisely similar results were subsequently obtained by ,buchner and ,antoni #aije1 #b by the dialysis of yeast-juice4 ,one hundred c4c4 of juice were dialysed for twenty-four hours at #j against #acjj c4c4 of distilled water1 and the dialysate was then evaporated at #dj to #ej to #bj c4c4 ,the fermenting power of #bj c4c4 of the dialysed juice was then determined with the following additions3-- 7#a7 #bj c4c4 of dialysed juice #aj c4c4 of water gave #jjb gram ,,co#b4 7#b7 #bj c4c4 of dialysed juice #aj c4c4 of evaporated dialysate gave #jeb gram ,,co#b4 7#c7 #bj c4c4 of dialysed juice #aj c4c4 of boiled juice gave #jhi gram ,,co#b4 ,it was shown in the previous chapter that phosphates are essential to fermentation1 and hence it becomes necessary to inquire whether the effect of dialysis is simply to remove these4 ,experiment shows that this is not the case4 ,soluble phosphates do not confer the power of producing fermentation on the inactive residue obtained by filtration4 ,moreover1 when yeast-juice is digested for some time before being boiled1 it is found1 as will be subsequently described1 that the boiled autolysed juice is quite incapable of setting up fermentation in the inactive residue1 although free phosphates are abundantly present ,harden and ,young1 #aijf1 #b4 ,the filtration residue is never obtained quite free from combined phosphorus1 but the production from this of the phosphate necessary for fermentation to proceed1 may be so slow as to render the test for co-enzyme uncertain1 owing to the absence of sufficient phosphate4 ,when a filtration residue is being tested it is therefore necessary to secure the presence of sufficient phosphate to enable the characteristic reaction to proceed1 and at the same time to avoid adding phosphate in too great concentration1 as this may1 in the presence of only small amounts of enzyme or co-enzyme1 inhibit the fermentation 7p4 #ga74 ,the proof that a filtration residue or dialysed juice is quite free from co-enzyme is therefore a somewhat complicated matter1 and not only involves the experimental demonstration that the material will not ferment sugar1 but also that this power is not imparted to it by the addition of a small concentration of phosphate4 ,as it has been found 7p4 #gc7 that the fermentation of fructose is less affected than that of glucose by the presence of excess of phosphate1 the practical method of examining a filtration residue for co-enzyme is to test its action on a solution of fructose 7#a7 alone and 7#b7 in presence of a small concentration of phosphate4 ,if the residue produces no action p#jfc in either case1 but produces fermentation when a solution of co-enzyme is added in the presence of the same concentration of phosphate as was previously employed1 it may be concluded that this sample was free from co-enzyme but contained enzyme2 such an experiment also affords a definite proof that the co-enzyme does not consist of phosphate4 ,this dialysable1 thermostable substance1 without which alcoholic fermentation cannot proceed1 has been provisionally termed the co-ferment or co-enzyme of alcoholic fermentation4 ,this expression was first introduced by ,bertrand #ahig1 to denote substances of this kind1 and he applied it in two instances--to the calcium salt which he considered was necessary for the action of pectase on pecten substances1 and to the manganese which he supposed to be essential for the activity of laccase4 ,without inquiring whether these substances are precisely comparable in function with that contained in yeast-juice1 the term may be very well applied to signify the substance of unknown constitution without the co-operation of which the thermolabile enzyme of yeast-juice is unable to set up the process of alcoholic fermentation4 ,the active agent of yeast-juice consisting of both enzyme and co-enzyme may be conveniently spoken of as the fermenting complex1 and this term will occasionally be employed in the sequel4 ,the co-enzyme is present alike in the filtrates from fresh yeast-juice and from boiled yeast-juice1 and is also contained in the liquids obtained by boiling yeast with water and by washing zymin or dried yeast with water4 ,practically the only chemical property of the co-enzyme1 other than that of rendering possible the process of alcoholic fermentation1 which has so far been observed1 is that it is capable of being decomposed1 probably by hydrolysis1 by a variety of reagents1 prominent among which is yeast-juice4 ,this was observed by ,harden and ,young in the course of their attempts to prepare a completely inactive residue by filtration4 ,in many cases a residue was obtained which still possessed a very limited power of fermentation1 only a small amount of carbon dioxide being formed and the action ceasing entirely after the expiration of a short period2 on the subsequent addition of boiled juice1 however1 a very considerable evolution of carbon dioxide was produced4 ,this was interpreted to mean that the residue in question contained an ample supply of enzyme but only a small proportion of co-enzyme1 and that the latter was rapidly destroyed1 so that the fermentation soon ceased4 ,the boiled juice then added provided a further proportion of co-enzyme by the aid of which the surplus enzyme was p#jfd enabled to carry on the fermentation4 ,this view was confirmed by adding to a solution of a completely inactive filtration residue and glucose successive small quantities of boiled juice and observing the volumes of carbon dioxide evolved after each such addition4 ,thus in one case successive additions of volumes of #c c4c4 of boiled juice produced evolutions of #hb1 #f1 and #f c4c4 of carbon dioxide4 ,in another case two successive additions of #ae c4c4 of boiled juice produced evolutions of #ed and #dab c4c4 ,on the other hand1 the enzyme itself also gradually disappears from yeast-juice when the latter is incubated either alone or with sugar 7p4 #bj74 ,the cessation of fermentation in any particular mixture of enzyme and co-enzyme may1 therefore1 be due to the disappearance of either of these factors from the liquid4 ,if the amount of co-enzyme present be relatively small it is the first to disappear1 and fermentation can then only be renewed by the addition of a further quantity1 whilst the addition of more enzyme produces no effect4 ,if1 on the other hand1 the amount of co-enzyme be relatively large1 the inverse is true2 the enzyme is the first to disappear1 and fermentation can only be renewed by the addition of more enzyme1 a further quantity of co-enzyme producing no effect4 ,it has1 moreover1 been found that the co-enzyme1 like the enzyme1 disappears more rapidly in the absence of glucose than in its presence1 incubation at #be for two days being as a rule sufficient to remove all the co-enzyme from yeast-juice from top yeasts in the absence of sugar1 whilst in the presence of fermentable sugar co-enzyme may still be detected at the end of four days4 ,in all the experiments carried out by ,harden and ,young with juice from ,english top yeast it was found that when a mixture of the juice with glucose was incubated until fermentation had ceased1 the further addition of co-enzyme in the form of boiled juice did not cause any renewal of the action2 in other words1 the whole of the enzyme had disappeared4 ,on the other hand1 ,buchner and ,klatte #aijh1 working with juice and zymin prepared from bottom yeast1 observed the extremely interesting fact that after the cessation of fermentation the addition of an equal volume of boiled juice caused a renewed decomposition of sugar1 and that the processes of incubation until no further evolution of gas occurred and re-excitation of fermentation by the boiled juice could be repeated as many as six times4 ,thus in one experiment the duration of the fermentation was extended from three to a total of twenty-four days1 and the total gas evolved from #jgc gram to #bai grams4 ,the phenomenon has been found to be common to yeast from ,munich and p#jfe from ,berlin as well as to zymin and maceration extract1 and it was further observed that the boiled juice from one yeast could regenerate the juice from another1 although the quantitative relations were different4 ,in these samples of yeast-juice1 therefore1 there is present a natural condition of affairs precisely similar to that obtaining in the artificial mixtures of inactive filtration residue and co-enzyme solution made by ,harden and ,young4 ,the balance of quantities is such that the co-enzyme disappears before the enzyme1 leaving a certain amount of enzyme capable of exercising its usual function as soon as sufficient co-enzyme is added4 ,this establishes an interesting point of contrast with the juice prepared from top yeast in ,england1 in which the enzyme does not outlast the co-enzyme ,harden and ,young1 #aijg4 ,the difference may be due to some variation in the relative proportions of enzyme and co-enzyme or of the enzymes to which the disappearance of each of these is presumptively due1 or to a combination of these two causes4 ,it was1 however1 found1 even in the juice from bottom yeast1 that incubation for three days at #bb without the addition of sugar caused the disappearance of the enzyme as well as of the co-enzyme1 and left a residue alike incapable of being regenerated by the addition of co-enzyme or of restoring the power of producing fermentation to an inactive mixture containing enzyme and sugar4 ,if the fermenting power of the juice is to be preserved by repeated regeneration for a long period1 it is absolutely necessary to add the co-enzyme solution each time as soon as fermentation has ceased1 since the enzyme in the absence of this addition rapidly disappears1 even in the presence of sugar4 ,this result is probably to be explained1 at all events in the main1 by the presence in the co-enzyme solution of the antiprotease to which reference has already been made ,buchner and ,haehn1 #aiaj1 #b4 ,this agent1 the constitution of which is still unknown1 protects proteins in general from the action of digestive enzymes1 and on the assumption that the alcoholic enzyme of yeast-juice belongs to the class of proteins1 may be supposed to lessen the rate at which this enzyme is destroyed by the endotryptase of the juice4 ,this antiprotease is1 like the co-enzyme 7p4 #fh71 destroyed by lipase but is more stable than the co-enzyme towards hydrolytic agents1 and can be obtained free from co-enzyme by boiling the solution for some hours alone or by heating with dilute sulphuric acid4 ,such a solution possesses no regenerative power1 but still retains its power of protecting proteins against digestion and of preserving the fermenting power of yeast-juice4 p#jff ,it must1 however1 be remembered that the addition of a phosphate alone may greatly prolong the period of fermentation of yeast-juice 7p4 #ee71 and sugar is well known to exert a similar action4 ,it appears1 therefore1 that the existence of the enzyme is prolonged not only by the presence of the antiprotease but also by that of sugar and hexosephosphate1 into which phosphate passes in presence of sugar4 ,similar effects are exerted on the co-enzyme by sugar and probably also by hexosephosphate4 ,the fermenting complex1 therefore1 in the presence of these substances1 either separately or together1 falls off more slowly in activity and is present for a longer time1 and for both of these reasons produces an increased amount of fermentation4 ,it seems probable also that the hexosephosphatase is similarly affected1 so that the supply of free phosphate is at the same time better maintained1 and the rate of fermentation for this reason decreases more slowly than would otherwise be the case4 ,it is in this way that an explanation may be found of the remarkable increase in total fermentation1 which is produced by the addition to yeast-juice and sugar of boiled yeast-juice1 containing free phosphate 7which passes into hexosephosphate7 as well as co-enzyme1 of boiled autolysed yeast-juice1 containing free phosphate but no co-enzyme1 or of phosphate solution alone4 ,in no case is the original rate of fermentation greatly increased after the initial acceleration has disappeared1 but in every case the total fermentation is considerably augmented1 and this is no doubt mainly to be attributed1 as just explained1 to the diminished rate of decomposition of the fermenting complex and probably of the hexosephosphatase4 ,although both enzyme and co-enzyme are completely precipitated from yeast-juice1 as already described 7p4 #ch71 by #aj volumes of acetone1 the co-enzyme is less easily precipitated than the enzyme1 and a certain degree of separation can therefore be attained by fractional precipitation ,buchner and ,duchaek1 #aiji4 ,the enzyme cannot1 however1 be completely freed from co-enzyme in this manner1 and the process is attended by a very considerable loss of enzyme4 ,this is probably due to the fact that only small quantities of acetone can be added 7#ae to #c volumes71 in order to avoid precipitation of co-enzyme1 and that the precipitates thus formed contain a large proportion of water1 a condition which appears to be fatal to the preservation of the enzyme4 ,it is1 however1 not quite certain whether it is the zymase or the hexosephosphatase which is destroyed in these cases1 as no attempt ,pg #jfg was made to distinguish between them4 ,in any case the precipitates obtained by fractional treatment with acetone1 even when reunited1 produce a much smaller fermentation than the original juice or the powder prepared by bringing it into #aj volumes of acetone4 ,attempts to isolate the co-enzyme from boiled yeast-juice have also been hitherto unsuccessful4 ,it has1 however1 been found possible to remove a considerable amount of material from the solution without affecting the co-enzyme4 ,when #a volume of alcohol is added to boiled yeast-juice1 a bulky precipitate1 consisting largely of carbohydrates1 is produced1 and the filtrate from this is found to contain the co-enzyme and can be freed from alcohol by evaporation4 ,further precipitation with alcohol has not led to useful results4 ,when a solution which has been treated in this way is precipitated with lead acetate and kept neutral to litmus1 the free phosphate and hexosephosphate are thrown down and the co-enzyme remains in solution4 ,the filtrate can be freed from lead by means of sulphuretted hydrogen and neutralised1 and then forms a solution of co-enzyme free from phosphate and hexosephosphate but still containing combined phosphorus4 ,more complete purification than this has not yet been accomplished4 ,occasionally the precipitate of lead salts retains some of the co-enzyme1 apparently by adsorption1 but usually the greater part remains in the solution 7,harden and ,young74 ,the co-enzyme is partially removed from yeast-juice by means of a colloidal solution of ferric hydroxide 7,resenscheck74 ,a precipitate is thus obtained which contains phosphorus and resembles boiled yeast-juice in its regenerative action on yeast-juice rendered inactive by fermentation4 ,it has not1 however1 so far been found possible to isolate any definite compound from this precipitate4 ,there are also indications that when yeast-juice1 either fresh or boiled1 is electrolysed1 the co-enzyme tends to accumulate at the cathode ,resenscheck1 #aijh1 #a1 #b4 ,buchner and ,klatte #aijh made use of yeast-juice rendered free from co-enzyme by incubation with sugar solution to examine the nature of the agent by which the co-enzyme is destroyed4 ,this agent is certainly an enzyme1 since boiled yeast-juice can be preserved with unimpaired powers for a considerable length of time1 and suspicion fell naturally1 in the first instance1 on the endotryptase of the yeast cell4 ,direct experiment showed1 however1 that yeast-juice1 which1 when fresh1 rapidly destroyed the co-enzyme of boiled juice1 lost this power on preservation1 but retained its proteoclastic properties without diminution1 so that the tryptic enzyme could not be the one concerned4 ,the direct action of commercial trypsin on boiled yeast-juice also yielded p#jfh a negative result1 although this cannot strictly be regarded as an indication of the effect of the specific proteoclastic enzymes of yeast-juice4 ,on the other hand1 it was found that when boiled juice was treated for some time with an emulsion containing the lipase of castor oil seeds1 the co-enzyme was completely destroyed4 ,this is a result of great importance1 inasmuch as it probably indicates that the co-enzyme is chemically allied to the class of substances hydrolysable by lipase1 i4e4 to the fats and other esters4 ,further1 observations by ,buchner and ,haehn #aiji have shown that digestion with potassium carbonate solution containing #be grams per #ajj c4c4 also brings about the destruction of the co-enzyme1 and that this is also slowly accomplished by the repeated boiling of the juice4 ,the co-enzyme is also destroyed both by acid and alkaline hydrolysis1 and when the solution is evaporated to dryness and the residue ignited4 ,beyond this general indication nothing is known of the chemical nature of the co-enzyme4 ,the intimate relation of phosphoric acid to the process of fermentation renders it not impossible that the co-enzyme may contain this group1 but there is no definite evidence for such a belief4 ,purely negative results have been obtained with all the substances of known composition which have yet been tested1 among these being soluble phosphates1 hexosephosphates and a number of oxidisable and reducible substances1 such as quinol1 p-phenylenediamine1 methylene blue1 peptone beef broth1 etc4 7,harden and ,young2 ,harden and ,norris #aiad2 see also ,euler and ,bckstrm #aiab71 glycero-phosphates 7,buchner and ,klatte74 ,the precise function of the co-enzyme is even more obscure than its chemical nature4 ,the system of reacting substances consisting of fermentable material1 enzyme and co-enzyme1 bears1 however1 an obvious superficial resemblance to many of the systems required for the accomplishment of chemical changes in the animal or vegetable organism4 ,such a triad of substances is1 for example1 requisite for the process by which the red blood corpuscles of an animal are broken up by the serum of a different animal into the blood of which the red corpuscles of the first animal have been injected4 ,this effect is only produced when two substances are present1 the amboceptor or immune body and the complement4 ,the analogy may be carried to a further stage since the amboceptor is1 like the co-enzyme1 more thermostable than the complement1 which therefore corresponds with the enzyme4 ,immune serum can1 in fact1 be freed from complement by being heated at #eg-fj for half an hour1 whereas the amboceptor is unaffected by this treatment4 ,on the other hand1 the complement and amboceptor do not p#jfi appear to act like enzymes but rather like ordinary chemical reagents1 remaining in combination even after the blood corpuscle has been broken up1 whereas the enzyme and co-enzyme of yeast-juice are again liberated when the reaction between sugar and phosphate has been completed4 ,pg #jgj ,,chapter ,v4 ,,action ,,of ,,some ,,inhibiting ,,and ,,accelerating ,,agents ,,on ,,the ,,enzymes ,,of ,,yeast-,,juice4 ,one of the most interesting and at the same time most difficult problems concerning enzyme action in general is the nature of the inhibiting or accelerating effect produced by many substances upon the rate or total result of the chemical process set up in presence of the enzyme4 ,inhibition1 it is usually supposed1 involves either the decomposition of the enzyme1 in which case it is irreversible1 its removal from the sphere of action by some change in its mode of solution1 or the formation of an inactive or less active compound between the enzyme and the inhibiting agent4 ,this compound it may sometimes be possible to decompose1 with the result that the activity of the enzyme is restored4 ,a striking example of this1 to which allusion has already been made1 is the effect of hydrocyanic acid on alcoholic fermentation 7p4 #cg74 ,acceleration of enzyme action can in some cases be ascribed to the fact that the accelerating substance possesses an assignable chemical function in the reaction1 so that an increase in the concentration of this substance causes an increase in the rate of the reaction4 ,as we have seen in ,chapter ,,iii1 this is the explanation of the accelerating effect of phosphates on fermentation by yeast-juice4 ,in many other cases1 however1 no such chemical function can be traced1 as1 for example1 in the effect of neutral salts on the hydrolytic action of invertase1 or the effect of the addition of the co-enzyme to zymase1 and it is necessary to fall back on some assumption1 such as that the accelerating agent acts by increasing the effective concentration of the enzyme or by combining either with the enzyme or the substrate1 forming a compound which undergoes the reaction more readily4 ,the interest in the following examples of inhibition and acceleration of fermentation by yeast-juice lies not only in their relation to these general problems but also1 and perhaps chiefly1 in their bearing on the specific problem of the nature and mode of action of the various agents concerned in the production of alcohol and carbon dioxide from sugar in the yeast-cell4 p#jga ,i4 ,,influence ,,of ,,concentration ,,of ,,phosphate ,,on ,,the ,,course ,,of ,,fermentation4 ,prominent among these instances of inhibition and acceleration are the phenomena attendant on the addition of excess of phosphate to yeast-juice4 ,when a phosphate is added to a fermenting mixture of a sugar and yeast-juice1 the effect varies with the concentration of the phosphate and the sugar and with the particular specimen of yeast-juice employed4 ,with low concentrations of phosphate in presence of excess of glucose the acceleration produced is so transient that no accurate measurements of rate can be made4 ,as soon as the amount of phosphate added is sufficiently large1 it is found that the rate of evolution of carbon dioxide very rapidly increases from five to ten times1 and then quickly falls approximately to its original value4 ,as the concentration of phosphate is still further increased1 it is first observed that the maximum velocity1 which is still attained almost immediately after the addition of the phosphate1 is maintained for a certain period before the fall commences1 and then1 as the increase in concentration of phosphate proceeds1 that the maximum is only gradually attained after the addition1 the period required for this increasing with the concentration of the phosphate4 ,moreover1 with still higher concentrations1 the maximum rate attained is less than that reached with lower concentrations1 and further1 the rate falls off more slowly4 ,the concentration of phosphate which produces the highest rate1 which may be termed the optimum concentration1 varies very considerably with different specimens of yeast-juice ,harden and ,young1 #aijh1 #a4 ,all these points are illustrated by the accompanying curves 7,fig4 #g7 which show the rate of evolution per five minutes plotted against the time for four solutions in which the initial concentrations of phosphate were 7,a7 #jjcc1 7,b7 #jjfg1 7,c7 #ja1 and 7,d7 #jacc molar1 the volumes of #jc molar phosphate being #e1 #aj1 #ae1 and #bj c4c4 in each case added to #be c4c4 of yeast-juice1 and made up to #de c4c1 each solution containing #de grams of glucose4 ,the time of addition is taken as zero1 the rate before addition being constant1 as shown in the curves4 ,it will be observed that #e and #aj c4c4 7,a and ,b7 give the same maximum1 whilst #ae c4c4 7,c7 produce a much lower maximum1 and #bj c4c4 7,d7 a still lower one1 the rate at which the velocity diminishes after the attainment of the maximum being correspondingly slow in these last two cases4 ,by calculating the amount of phosphate which has disappeared as such from the amount of carbon dioxide evolved1 p#jgb it is found that the maximum does not occur at the same concentration of free phosphate in each case4 ,illustration3 ,,fig4 #g4 7,graph ,,co#b rate vs time--,ed47 ,these results suggest that the phosphate is capable of forming two or more different unstable associations with the fermenting complex4 ,one of these1 formed with low concentrations of the phosphate1 has the composition most favourable for the decomposition of sugar1 whilst the others1 formed with higher concentrations of phosphate1 contain more of the latter1 probably associated in such a way with the fermenting complex as to render the latter partially or wholly incapable of effecting the decomposition of the sugar molecule4 ,as the fermentation proceeds slowly in the presence of excess of phosphate1 the concentration of the latter is reduced by conversion into hexosephosphate1 and a re-distribution of phosphate occurs1 resulting in the gradual change of the less active into the more active association of phosphate with fermenting complex1 and a consequent rise in the rate of fermentation4 ,in those cases in which the maximum rate corresponding to the optimum concentration of phosphate is never attained1 some secondary cause may be supposed to intervene1 such as a permanent change in a portion of the fermenting complex1 accumulation of the products of the reaction1 etc4 ,it is also possible as suggested by ,buchner for the analogous case of arsenite 7p4 #gh7 that the addition of increasing amounts of phosphate causes a progressive but reversible change in the mode of dispersion p#jgc of the colloidal enzyme1 and that this has the secondary effect of altering the rate of fermentation4 ,no decisive evidence is as yet available upon the subject4 ,the results obtained by ,euler and ,johansson #aiac to which reference has already been made indicate that in presence of a moderate excess of phosphate esterification is more rapid than production of carbon dioxide4 ,no explanation of this phenomenon has yet been given1 but it might obviously be due either to the production of some phosphorus compound which subsequently takes part in the production both of hexosediphosphate and of carbon dioxide1 or1 less probably1 to the entire independence of the two changes--esterification of phosphate and production of carbon dioxide--which might then be differently affected by the presence of excess of phosphate and therefore take place at different rates4 ,,ii4 ,,reaction ,,of ,,fructose ,,with ,,phosphates ,,in ,,presence ,,of ,,yeast-,,juice4 ,although1 as has been pointed out 7p4 #db71 glucose1 mannose1 and fructose all react with phosphate in a similar manner in presence of yeast-juice1 there are nevertheless certain quantitative differences between the behaviour of glucose and mannose on the one hand1 and fructose on the other1 which appear to be of considerable importance4 ,fructose differs from the other two fermentable hexoses in two particulars3 7#a7 the optimum concentration of phosphate is much greater2 7#b7 the maximum rate of fermentation attainable is much higher ,harden and ,young1 #aijh1 #b2 #aiji4 ,these points are clearly illustrated by the following results1 which all refer to #aj c4c4 of yeast-juice1 and show that the optimum concentration of phosphate for the fermentation of fructose is from #ae to #aj times that of glucose1 and that the maximum rate of fermentation for fructose in presence of phosphate is #b to #f times that of glucose4 ,sugar ,total ,optimum ,volume of ,maximum ,rate in ,cubic in ,volume4 #jf ,molar ,phosphate ,centimetres of ,,co#b ,grams4 in c4c4 per ,five ,minutes ,glucose4 ,fructose4 ,glucose4 ,fructose4 #b #ce #b #e #ge #cbb #d #ej #a #aj #ed #bhd #af #bc #b #e #h #ag #a #be #age #e #eb #bei #b #be #e #ge #afb #cab #b #bj #b #ce #gi #bbf #b #bbe #jge #b #cd #bbb p#jgd ,it is interesting to note that the two high rates1 #cbb and #cab c4c4 per five minutes1 are equal to about half the rate obtainable with an amount of living yeast corresponding to #aj c4c4 of yeast-juice1 assuming that about #af to #bj grams of yeast are required to yield this volume of juice1 and that this amount of yeast would give about #ef to #gj c4c4 of carbon dioxide per five minutes at #be1 which has been found experimentally to be about the rate obtainable with the top yeast employed for these experiments4 ,,iii4 ,,effect ,,of ,,the ,,addition ,,of ,,fructose ,,on ,,the ,,fermentation ,,of ,,glucose ,,or ,,mannose ,,in ,,presence ,,of ,a ,,large ,,excess ,,of ,,phosphate4 ,when the maximum rate of fermentation of glucose or mannose by yeast-juice in presence of phosphate is greatly lowered by the addition of a large excess of phosphate1 the addition of a relatively small amount of fructose 7as little as #be per cent4 of the weight of the glucose7 causes rapid fermentation to occur4 ,this induced activity is not due solely to the selective fermentation of the added fructose1 since the amount of gas evolved may be greatly in excess of that obtainable from the quantity added4 ,another way of expressing the same thing is to say that the optimum concentration of phosphate 7p4 #ga7 is greatly raised when #be per cent4 of fructose is added to glucose1 and that consequently the rate of fermentation rises4 ,the effect is extremely striking1 since a mixture of glucose and yeast-juice fermenting in the presence of a large excess of phosphate at the rate of less than #a c4c4 of carbon dioxide in five minutes may be made to ferment at six to eight times this rate by the addition of only #jje gram of fructose 7#be per cent4 of the glucose present71 and to continue until the total gas evolved is at least five to six times as great as that obtainable from the added fructose1 the concentration of the phosphate being the whole time at such a height as would limit the fermentation of glucose alone to its original value4 ,the effect is not produced when the concentration of the phosphate is so high that the rate of fermentation of fructose is itself greatly lowered4 ,this remarkable inductive effect is specific to fructose and is not produced when glucose is added to mannose or fructose1 or by mannose when added to glucose or fructose1 under the proper conditions of concentration of phosphate in each case4 ,this interesting property of fructose1 taken in connection with the p#jge facts that this sugar in presence of phosphate is much more rapidly fermented than glucose or mannose1 and that the optimum concentration of phosphate for fructose is much higher than for glucose or mannose1 appears to indicate that fructose when added to yeast-juice does not merely act as a substance to be fermented1 but in addition1 bears some specific relation to the fermenting complex4 ,all the phenomena observed are1 indeed1 consistent with the supposition that fructose actually forms a permanent part of the fermenting complex1 and that1 when the concentration of this sugar in the yeast-juice is increased1 a greater quantity of the complex is formed4 ,as the result of this increase in the concentration of the active catalytic agent1 the yeast-juice would be capable of bringing about the reaction with sugar in presence of phosphate at a higher rate1 and at the same time the optimum concentration of phosphate would become greater1 exactly as is observed4 ,the question whether1 as suggested above1 fructose actually forms part of the fermenting complex1 and the further questions1 whether1 if so1 it is an essential constituent1 or whether it can be replaced by glucose or mannose with formation of a less active complex1 remain at present undecided1 and cannot profitably be more fully discussed until further information is available4 ,it must1 moreover1 be remembered that different samples of yeast-juice vary to a considerable extent in their relative behaviour to glucose and fructose1 so that the phenomena under discussion may be expected to vary with the nature and past history of the yeast employed4 ,,iv4 ,,effect ,,of ,,arsenates ,,on ,,the ,,fermentation ,,of ,,sugars ,,by ,,yeast-,,juice ,,and ,,zymin4 ,the close analogy which exists between the chemical functions of phosphorus and arsenic lends some interest to the examination of the action of sodium arsenate upon a mixture of yeast-juice and sugar1 and experiments reveal the fact that arsenates produce a very considerable acceleration in the rate of fermentation of such a mixture ,harden and ,young1 #aijf1 #c2 #aiaa1 #a4 ,the phenomena observed1 however1 differ markedly from those which accompany the action of phosphate4 ,the acceleration produced is of the same order of magnitude as that obtained with phosphate1 but it is maintained without alteration for a considerable period1 so that there is no equivalence between the amount of arsenate added and the extra amount of fermentation effected4 ,further1 no organic arsenic compound corresponding in composition with the hexosephosphates appears to be formed4 ,increase of concentration of arsenate produces a rapid inhibition of p#jgf fermentation1 probably due to some secondary effect on the fermenting complex1 possibly to be interpreted as the formation of compounds incapable of combining with sugar and hence unable to carry on the process of fermentation4 ,an optimum concentration of arsenate therefore exists just as of phosphate1 at which the maximum rate is observed1 and this optimum concentration and the corresponding rate vary with different samples of juice and are less for glucose than for fructose4 ,the rate of fermentation by zymin is relatively less increased than that by yeast-juice4 ,owing to the fact that the rate is permanently maintained the addition of a suitable amount of arsenate increases the total fermentation produced to a much greater extent than phosphate4 ,the nature of these effects may be gathered from the result of a few typical experiments4 ,in one case the rate of fermentation of glucose by yeast-juice was raised by the presence of #jjc molar arsenate from #b to #bc c4c4 per five minutes1 and the total evolved in ninety-five minutes from #ea to #dei c4c4 ,the accelerating effect on #bj c4c4 of juice1 of as little as #jjje c4c4 of #jc molar arsenate1 containing #jaa mgrm4 of arsenic1 can be distinctly observed1 but the maximum effect is usually produced by about #a to #c c4c41 the concentration being therefore #jjae to #jjde molar4 ,greater concentrations than this produce a less degree of acceleration accompanied by a shorter duration of fermentation1 as shown by the following numbers which refer to #bj c4c4 of yeast-juice in a total volume of #dj c4c4 containing #aj per cent4 of glucose3-- ,c4cs4 of ,molar ,maximum #jc ,molar ,concentration of ,rate of ,arsenate ,arsenate4 ,fermentation4 in #dj c4c4 #j #j #ce #jjje #jjjjjcge #fc #jja #jjjjjge #h #jjb #jjjjae #adb #jjd #jjjjc #aii #ja #jjjjge #big #jb #jjjae #ce #je #jjjcge #cdi #aj #jjjge #bie #bj #jjae #bcb #ej #jjcge #ade #ajj #jjge #hg #aej #jaabe #ec #bj #jae #cb ,the contrast between glucose and fructose in their relations to p#jgg arsenate are well exhibited in the following table1 in which the rates of fermentation produced by arsenate in presence of excess of glucose and fructose respectively are given3-- ,rate4 ,concentration of ,arsenate4 ,glucose4 ,fructose4 #jjjge molar #aba #bff #jjbbe 7opt4 for glucose7 #acd -- #jjebe 7opt4 for fructose7 -- #deh #jaabe #ea #ci ,here the optimum concentration for fructose is more than twice that for glucose1 whilst the maximum rate of fermentation obtainable with fructose is between three and four times the maximum given by glucose4 ,v4 ,,effect ,,of ,,arsenites ,,on ,,the ,,fermentation ,,produced ,,by ,,yeast-,,juice4 ,effects somewhat similar to those produced by arsenates were observed by ,buchner ,buchner and ,rapp1 #ahig2 #ahih1 #a1 #b1 #c2 #ahii1 #b2 ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 pp4 #ahd-bje when potassium arsenite was added to yeast-juice4 ,this substance1 the action of which on yeast had been adduced by ,schwann as a proof of the vegetable nature of this organism1 was employed by ,buchner on account of its poisonous effect on vegetable cells as an antiseptic and as a means of testing for the protoplasmic nature of the agent present in yeast-juice4 ,its effect on the fermentation was1 however1 found to be irregular1 and at the same time it did not act as an efficient antiseptic in the concentrations which could be employed4 ,even #b per cent4 of arsenious oxide1 added as the potassium salt1 had in many cases a decided effect in diminishing the total fermentation obtained with cane sugar1 and this effect increased with the concentration4 ,a number of irregularities were also observed which cannot here be discussed4 ,it was further found that in some cases #b per cent4 of arsenious oxide inhibited the fermentation of glucose but not of saccharose1 or of a mixture of glucose and fructose1 whilst its effect on fructose alone was of an intermediate character4 ,the important observation was also made by ,buchner that the addition of a suitable quantity of arsenite as a rule caused a greatly increased fermentation during the first sixteen hours even in experiments in which the total fermentation was diminished4 ,by examining the effect of arsenite on fermentation in a similar manner to that of arsenate1 ,harden and ,young #aiaa1 #a have found that a close analogy exists ,pg #jgh between the effects and modes of action of these substances1 but that arsenite produces a much smaller acceleration than arsenate4 ,an optimum concentration of arsenite exists1 just as in the case of arsenate1 which produces a maximum rate of fermentation4 ,further increase in concentration leads to inhibition1 and in no case is there any indication of the production of an exactly equivalent amount of fermentation as in the case of phosphate4 ,in various experiments with dialysed1 evaporated1 and diluted yeast-juice in which #b per cent4 of arsenious oxide was found by ,buchner to inhibit fermentation1 it is probable that1 owing to the small amount of fermenting complex left1 this amount of arsenious oxide was considerably in excess of the optimum concentration1 although ,buchner ascribes the effect to the removal of some of the protective colloids of the juice1 owing to the prolonged treatment to which it had been subjected4 ,the extent of the action of arsenite appears from the following results4 ,in one case a rate of #ag c4c4 was increased to #g c4c4 by #jjf molar arsenite4 ,in another experiment it was found that the optimum concentration was #jjd molar arsenite1 the addition of which increased the rate three-fold4 ,as in the case of arsenate the optimum concentration and the corresponding maximum rate of fermentation are considerably greater for fructose than for glucose4 ,the relative rates produced by the addition of equivalent amounts of arsenate and arsenite 7#a c4c4 of #jc molar solution in each case to #bj c4c4 of yeast-juice7 were #bge and #ca1 the original rate of the juice being #ag4 ,in general the optimum concentration of arsenite is considerably greater than that of arsenate4 ,the inhibiting effects of higher concentrations of arsenite and arsenate also present close analogies1 but this most interesting aspect of the question has not yet been sufficiently examined to repay detailed discussion4 ,buchner ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 pp4 #aii-bje has suggested that the inhibition is due primarily to some change in the colloidal condition of the enzyme and has shown that certain colloidal substances appear to protect it1 as does also sugar4 ,the possibility is also present that inactive combinations of some sort are formed between the fermenting complex and the inhibiting agent1 in the manner suggested to account for the inhibiting effect of excess of phosphate 7p4 #gb74 ,it seems most probable that the effect is a complex one1 in which many factors participate4 ,,nature ,,of ,,the ,,acceleration ,,produced ,,by ,,arsenate ,,and ,,arsenite4 ,in explanation of the remarkable accelerating action of arsenates and arsenites two obvious possibilities present themselves4 ,in the p#jgi first place the arsenic compound may actually replace phosphate in the reaction characteristic of alcoholic fermentation1 the resulting arsenic analogue of the hexosephosphate being so unstable that it undergoes immediate hydrolysis1 and is therefore only present in extremely small concentration at any period of the fermentation and cannot be isolated4 ,in the second place it is possible that the arsenic compound may accelerate the action of the hexosephosphatase of the juice1 and thus by increasing the rate of circulation of the phosphate produce the permanent rise of rate4 ,with this effect may possibly be associated a direct acceleration of the action of the fermenting complex4 ,the experimental decision between these alternative explanations is rendered possible by the use of a mixture of enzyme and co-enzyme free from phosphate and hexosephosphate4 ,as has already been described 7p4 #ee7 a mixture of boiled yeast-juice1 which has been treated with lead acetate1 glucose or fructose1 and washed zymin can be prepared which scarcely undergoes any fermentation unless phosphate be added4 ,if now arsenates or arsenites can replace phosphate1 they should be capable of setting up fermentation in such a mixture4 ,experiment shows that they do not possess this power4 ,for fermentation to proceed phosphate must be present and it cannot be replaced either by arsenate or arsenite ,harden and ,young1 #aiaa1 #a4 ,the effect of these salts on the action of the hexosephosphatase can also be ascertained by a modification of the foregoing experiment4 ,if a hexosephosphate be made the sole source of phosphate in such a mixture as that described above1 in which it must be remembered abundance of sugar is present1 the rate at which fermentation can proceed will be controlled by the rate at which the hexosephosphate is decomposed with formation of phosphate4 ,experiment shows that in the presence of added arsenate or arsenite the rate of fermentation is largely increased1 so that the effect of these salts must be to increase the rate of liberation of phosphate1 or in other words1 to accelerate the hydrolytic action of the hexosephosphatase4 ,this conclusion is even more strikingly confirmed by a comparison of the direct action of yeast-juice on hexosephosphate in presence and in absence of arsenate1 as measured by the actual production of free phosphate4 ,in a particular experiment this gave rise to #jjgjg gram of ,mg#b,p#b,o#g in the absence of arsenate and #jfacf gram of ,mg#b,p#b,o#g in the presence of arsenate4 ,the results obtained with arsenite are throughout very similar to those given by arsenate1 but are not quite so striking4 ,it may therefore be affirmed with some confidence that the chief action of arsenates p#jhj and arsenites in accelerating the rate of fermentation of sugars by yeast-juice or zymin1 consists in an acceleration of the rate at which phosphate is produced from the hexosephosphate by the action of the hexosephosphatase4 ,it has further been found that arsenates1 and to a less degree arsenites1 also produce an acceleration of the rate of autofermentation of yeast-juice and of the rate at which glycogen is fermented4 ,this turns out to be due in all probability to an increase in the activity of the glycogenase by the action of which the sugar is supplied which is the direct subject of fermentation4 ,thus in one case an initial rate of fermentation of glycogen of #ai c4c4 per five minutes was increased by #jje molar arsenate to #ig and the amount of carbon dioxide evolved in two hours from #ch to #aeh c4c4 ,even this enhanced production of glucose from glycogen1 however1 is not nearly sufficient for the complete utilisation of the phosphate also being liberated by the action on the hexosephosphatase1 for the addition of an excess of sugar produces a much higher rate1 in this case #cf c4c4 per five minutes4 ,the effect of arsenate on the rate of action of the glycogenase seems therefore to be much smaller than on that of the hexosephosphatase4 ,no other substances have yet been found which share these interesting properties with arsenates and arsenites1 and no advance has been made towards an understanding of the mechanism of the accelerating action of these salts on the specific enzymes which are affected by them4 p#jha ,,chapter ,,vi4 ,,carboxylase4 ,an observation of remarkable interest1 which promises to throw light on several important features of the biochemistry of yeast1 was made in #aiaa1 and has since then formed the subject of detailed investigation by ,neuberg and a number of co-workers4 ,it was found that yeast had the power of rapidly decomposing a large number of hydroxy-and keto-acids ,neuberg and ,hildesheimer1 #aiaa2 ,neuberg and ,tir1 #aiaa2 see also ,karczag1 #aiab1 #a1 #b4 ,the most important among these are pyruvic acid1 ,,ch#c;,,co,,cooh1 and a considerable number of other aliphatic a-keto-acids which are decomposed with evolution of carbon dioxide and formation of the corresponding aldehyde3-- ,r,,co,,cooh ,r,,cho ,,co#b4 ,the reaction is produced by all races of brewer's yeast which have been tried1 as well as by active yeast preparations and extracts and by wine yeasts ,neuberg and ,karczag1 #aiaa1 #d2 ,neuberg and ,kerb1 #aiab1 #b4 ,the phenomenon can readily be exhibited as a lecture experiment by shaking up #b g4 of pressed yeast with #ab c4c4 of #a per cent4 pyruvic acid1 placing the mixture in a ,schrtter's fermentation tube1 closing the open limb by means of a rubber stopper carrying a long glass tube and plunging the whole in water of #ch-dj4 ,comparison tubes of yeast and water and yeast and #a per cent4 glucose may be started at the same time1 and it is then seen that glucose and pyruvic acid are fermented at approximately the same rate ,neuberg and ,karczag1 #aiaa1 #a4 ,if ,english top yeast be used it is well to take #je per cent4 pyruvic acid solution and to saturate the liquids with carbon dioxide before commencing the experiment4 ,the production of acetaldehyde can be readily demonstrated by distilling the mixture at the close of fermentation and testing for the aldehyde either by ,rimini's reaction 7a blue coloration with diethylamine and sodium nitroprusside7 or by means of p-nitrophenylhydrazine which precipitates the hydrazone1 melting at #abhe ,neuberg and ,karczag1 #aiaa1 #b1 #c4 p#jhb ,as the result of quantitative experiments it has been shown that #hj per cent4 of the theoretical amount of acetaldehyde can be recovered4 ,the salts of the acids are also attacked1 the carbonate of the metal1 which may be strongly alkaline1 being formed4 ,thus taking the case of pyruvic acid1 the salts are decomposed according to the following equation3-- #b;,,ch#c;,,co,,cook ,h#b,o #b;,,ch#c;,,cho ,k#b;,,co#c ,,co#b4 ,under these conditions a considerable portion of the aldehyde undergoes condensation to aldol ,neuberg1 #aiab3-- #b;,,ch#c;,,cho ,,ch#c;,,ch7,,oh7,,ch#b;,,cho4 ,this change appears to be due entirely to the alkali and not to an enzyme since the aldol obtained yields inactive -hydroxybutyric acid on oxidation ,neuberg and ,karczag1 #aiaa1 #c2 ,neuberg1 #aiab4 ,the various preparations derived from yeast which are capable of producing alcoholic fermentation also effect the decomposition of pyruvic acid in the same manner as living yeast4 ,they are1 however1 more sensitive to the acidity of the pyruvic acid1 and it is therefore advisable to employ a salt of the acid in presence of excess of a weak acid1 such as boric or arsenious acid1 which decomposes the carbonate formed but has no inhibiting action on the enzyme ,harden1 #aiac2 ,neuberg and ,rosenthal1 #aiac4 ,as already mentioned the action is exerted on -ketonic acids as a class and proceeds with great readiness with oxalacetic acid1 ,,cooh,,ch#b;,,co,,cooh1 all the three forms of which are decomposed1 with -ketoglutaric acid1 and with -ketobutyric acid4 ,hydroxypyruvic acid ,,ch#b7,,oh7,,co,,cooh is slowly decomposed yielding glycolaldehyde1 ,,ch#b7,,oh7,,cho1 and this condenses to a sugar ,neuberg and ,kerb1 #aiab1 #c2 #aiac1 #a4 ,positive results have also been obtained with diketobutyric1 phenylpyruvic1 p-hydroxyphenylpyruvic1 phenylglyoxylic and acetonedicarboxylic acids ,neuberg and ,karczag1 #aiaa1 #e4 ,,relation ,,of ,,carboxylase ,,to ,,alcoholic ,,fermentation4 ,with regard to the relation of carboxylase to the process of alcoholic fermentation1 nothing definite is yet known4 ,as ,neuberg points out see ,neuberg and ,kerb1 #aiac1 #a the universal presence of the enzyme in yeasts capable of producing alcoholic fermentation1 and the extreme readiness with which the fermentation of pyruvic acid takes place create a p#jhc strong presumption that the decomposition of pyruvic acid actually forms a stage in the process of the alcoholic fermentation of the sugars4 ,on the other hand ,ehrlich's alcoholic fermentation of the amino-acids 7p4 #hg7 provides another function for carboxylase--that of decomposing the -ketonic acids produced by the deaminisation of the amino-acids4 ,it must be remembered in this connection that carboxylase is not specific in its action1 but catalyses the decomposition not only of pyruvic acid but also of a large number of other -ketonic acids1 including many of those which correspond to the amino-acids of proteins and are doubtless formed in the characteristic decomposition of these amino-acids by yeast4 ,carboxylase undoubtedly effects one stage in the production of alcohols from amino-acids1 whether it is also the agent by which one stage in the alcoholic fermentation of sugar is brought about still remains to be proved4 ,a comparison of the conditions of action of carboxylase and zymase has revealed several interesting points of difference4 ,neuberg and ,rosenthal #aiac have observed that the fermentation of pyruvic acid by maceration extract commences much more rapidly than that of glucose and interpret this to mean that in the fermentation of glucose a long preliminary process occurs before sufficient pyruvic acid has been produced to yield a perceptible amount of carbon dioxide4 ,the long delay 7#c hours7 which they sometimes observed in the action of maceration juice on glucose is however by no means invariable 7see p4 #df71 but in any case indicates that the sugar fermentation can be affected by conditions which are without influence on the pyruvic fermentation4 ,a similar conclusion is to be drawn from the fact that the pyruvic acid fermentation is less affected by antiseptics than the glucose fermentation ,neuberg and ,karczag1 #aiaa1 #d2 ,neuberg and ,rosenthal1 #aiac1 chloroform sufficient to stop the glucose fermentation brought about by yeast or dried yeast being usually without effect on the fermentation of the pyruvates either alone or in presence of boric or arsenious acid4 ,a more important difference is that carboxylase decomposes pyruvic acid in the absence of the co-enzyme which is necessary for the fermentation of glucose ,harden1 #aiac2 ,neuberg and ,rosenthal1 #aiac4 ,this can be demonstrated experimentally by washing dried yeast or zymin with water 7see p4 #fc7 until it is no longer capable of decomposing glucose 7,harden71 or by allowing maceration extract to autolyse or dialyse until it is free from co-enzyme 7,neuberg and ,rosenthal74 ,the zymase of maceration extract is moreover inactivated in #aj minutes at #ej-ea1 whereas after this treatment the carboxylase is still active4 p#jhd ,the only conclusion that can be legitimately drawn from these highly interesting facts is that if the decomposition of pyruvic acid actually be a stage in the alcoholic fermentation of glucose the soluble co-enzyme is required for some change precedent to this1 so that in its absence the production of pyruvic acid cannot be effected4 p#jhe ,,chapter ,,vii4 ,,the ,,by-,,products ,,of ,,alcoholic ,,fermentation4 ,when pure yeast is allowed to develop in a solution of sugar containing a suitable nitrogenous diet and the proper mineral salts1 the liquid at the close of the fermentation contains not only alcohol and some carbon dioxide but also a considerable number of other substances1 some arising from the carbonaceous and others from the nitrogenous metabolism of the cell4 ,prominent among the non-nitrogenous substances which are thus found in fermented sugar solutions are fusel oil1 succinic acid1 glycerol1 acetic acid1 aldehyde1 formic acid1 esters1 and traces of many other aldehydes and acids4 ,in addition to these substances which are found in the liquid1 there are also the carbonaceous constituents of the newly formed cells of the organism1 comprising the material of the cell walls1 yeast gum1 glycogen1 complex organic phosphates1 as well as other substances4 ,the attention of chemists has been directed to these compounds since ,pasteur first emphasised their importance as essential products of the alcoholic fermentation of sugar1 and his example was generally followed in attributing their origin to the sugar4 ,the study of cell-free fermentation by means of yeast-juice or zymin has1 however1 revealed the facts that certain of these substances are not formed in the absence of living cells1 and that their origin is to be sought in the metabolic processes which accompany the life of the cell4 ,their source1 moreover1 has been traced not to the sugar but to the amino-acids1 formed by the hydrolysis of the proteins1 which occur in all such liquids as beer wort1 grape juice1 etc41 which are usually submitted to alcoholic fermentation4 ,this has so far been proved with certainty for the fusel oil and succinic acid1 and rendered highly probable for all the various aldehydes and acids of which traces have been detected4 ,,fusel ,,oil4 ,all forms of alcohol prepared by fermentation contain a fraction of high boiling-point1 which is termed fusel oil1 and amounts to about p#jhf #ja to #jg per cent4 of the crude spirit obtained by distillation4 ,this material is not an individual substance1 but consists of a mixture of very varied compounds1 all occurring in small amount relatively to the ethyl alcohol from which they have been separated4 ,the chief constituents of the mixture are the two amyl alcohols1 isoamyl alcohol1 7,,ch#c7b;,,ch,,ch#b;,,ch#b,,oh1 and _/d_/-amyl alcohol1 ,,ch#c;,,ch7,c#b;,h#e7;,,ch#b,,oh1 which contains an asymmetric carbon atom and is optically active4 ,in addition to these1 much smaller amounts of propyl alcohol and isobutyl alcohol are present1 together with traces of fatty acids1 aldehydes1 and other substances4 ,the origin of these purely non-nitrogenous compounds was usually sought in the sugar of the liquid fermented1 from which they were thought to be formed by the yeast itself or by the agency of bacteria ,emmerling1 #aijd1 #aije2 ,pringsheim1 #aije1 #aijg1 #aijh1 #aiji1 whilst others traced their formation to the direct reduction of fatty acids4 ,felix ,ehrlich has1 however1 conclusively shown in a series of masterly researches that the alcohols1 and probably also the aldehydes1 contained in fusel oil are in reality derived from the amino-acids which are formed by the hydrolysis of the proteins4 ,the close relationship between the composition of leucine1 7,,ch#c7b;,,ch,,ch#b;,,ch7,,nh#b7;,,cooh 1 and isoamyl alcohol1 7,,ch#c7b;,,ch,,ch#b;,,ch#b,,oh1 had previously led to the surmise that a genetic relation might exist between these substances1 but the idea had not been experimentally confirmed4 ,in #aijc ,ehrlich discovered #aijc2 #aijd1 #a1 #b2 #aijg1 #b2 #aijh2 ,ehrlich and ,wendel1 #aijh1 #b that proteins also yield on hydrolysis an isomeride of leucine known as isoleucine1 which has the constitution ,,ch#c;,,ch7,c#b;,h#e7;,,ch7,,nh#b7;,,co oh1 and therefore stands to _/d_/-amyl alcohol1 ,,ch#c;,,ch7,c#b;,h#e7;,,ch#b,,oh1 in precisely the same relation as leucine to isoamyl alcohol4 ,this suggestive fact at once directed his attention to the problem of the origin of the amyl alcohols in alcoholic fermentation4 ,using a pure culture of yeast1 and thus excluding the participation of bacteria in the change1 he found that leucine readily yielded isoamyl alcohol1 and isoleucine _/d_/-amyl alcohol when these amino-acids were added in the pure state p#jhg to a solution of sugar and treated with a considerable proportion of yeast #aije2 #aijf1 #b1 #c2 #aijg1 #a1 #c4 ,the chemical reactions involved are simple ones and are represented by the following equations3-- 7#a7 7,,ch#c7b;,,ch,,ch#b;,,ch7,,nh#b7;,,cooh ,h#b,o ,leucine 7,,ch#c7b;,,ch,,ch#b;,,ch#b,,oh ,,co#b ,,nh#c ,isoamyl alcohol 7#b7 ,,ch#c;,,ch7,c#b;,h#e7;,,ch7,,nh#b7;,,co oh ,h#b,o ,isoleucine ,,ch#c;,,ch7,c#b;,h#e7;,,ch#b,,oh ,,co#b ,,nh#c _/d_/-,amyl alcohol ,the experiments by which these important changes were demonstrated were of a very simple and convincing character ,ehrlich1 #aijg1 #a4 ,two hundred grams of sugar and #c to #aj grams of the nitrogenous substance to be examined were dissolved in #b to #be litres of tap water in a #c to #d litre flask1 the liquid was sterilised by being boiled for several hours1 and after cooling #dj to #fj grams of fresh yeast were added and the flask allowed to stand at room temperature until the whole of the sugar had been decomposed by fermentation4 ,in the earlier experiments the amyl alcohols were isolated and identified by conversion into the corresponding valerianic acids1 but as a rule the fusel oil as a whole was quantitatively estimated in the filtrate by the ,rse-,herzfeld method ,lunge1 #aije1 p4 #ega4 ,the following are typical results4 7#a7 ,an experiment carried out as above without any addition of leucine gave #igcb grams of alcohol containing #jdj per cent4 of fusel oil4 7#b7 ,when #f grams of synthetic1 optically inactive leucine were added1 #igbf grams of alcohol were obtained1 containing #baa per cent4 of fusel oil1 which was also optically inactive2 #be grams of leucine were recovered1 so that #hg per cent4 of the theoretical yield of isoamyl alcohol was obtained from the #ce grams of leucine decomposed4 7#c7 ,in the presence of #be grams of _/d_/-isoleucine 7prepared from molasses residues71 #bjj grams of sugar gave #icii grams of alcohol1 containing #add per cent4 of fusel oil1 which was lvo-rotatory4 ,this corresponds with #hj per cent4 of the theoretical yield of _/d_/-amyl alcohol from the isoleucine added4 ,this change1 which ,ehrlich has termed the alcoholic fermentation of the amino-acids1 although brought about by living yeast1 does not appear to occur at all when zymin ,ehrlich1 #aijf1 #d2 ,pringsheim1 #aijf or yeast-juice ,buchner and ,meisenheimer1 #aijf is substituted for the intact organism1 nor is it effected even by living yeast in the absence of a fermentable sugar ,ehrlich1 #aijg1 #a4 ,the reaction appears indeed to be intimately connected with the nitrogenous metabolism of the cell1 and the whole of the ammonia produced is at once assimilated and does not appear in the fermented liquid4 ,other amino-acids p#jhh undergo a corresponding change1 and the reaction appears to be a general one4 ,thus tyrosine1 ,,oh,c#f;,h#d;,,ch#b;,,ch7,,nh#b7;,,cooh 1 yields p-hydroxyphenylethyl alcohol1 or tyrosol ,ehrlich1 #aiaa1 #a2 ,ehrlich and ,pistschimucka1 #aiab1 #b1 ,,oh,c#f;,h#d;,,ch#b;,,ch#b,,oh1 a substance of intensely bitter taste1 which was first prepared in this way and is probably one of the most important factors in determining the flavour of beers1 etc4 ,phenylalanine1 ,c#f;,h#e;,,ch#b;,,ch7,,nh#b7;,,cooh1 in a similar way yields phenylethyl alcohol1 ,c#f;,h#e;,,ch#b;,,ch#b,,oh1 one of the constituents of oil of roses1 whilst tryptophane1 ,c#f;,h#d ,,hn ,c,,ch#b;,,ch7,,nh#b7;,,cooh1 ,,ch yields tryptophol1 ,c#f;,h#d ,,hn ,c,,ch#b;,,ch#b,,oh1 ,,ch which was also first prepared in this way ,ehrlich1 #aiab and has a very faintly bitter1 somewhat biting taste4 ,the extent to which the amino-acids of a medium in which yeast is producing fermentation are decomposed in this sense depends on the amount of the available nitrogen and on the form in which it is present4 ,thus the addition of ammonium carbonate to a mixture of yeast and sugar was found to lower the production of fusel oil from #jg to #jcc per cent4 of the alcohol produced4 ,the addition of leucine alone raised the percentage from #jg to #bgh1 but the addition of both leucine and ammonium carbonate resulted in the formation of only #jgh per cent4 of fusel oil1 ,the production of fusel oil therefore and the character of the constituents of the fusel oil alike depend on the composition of the medium in which fermentation occurs4 ,this affords a ready explanation of the fact that molasses1 which contains almost equal amounts of leucine and isoleucine1 yields a fusel oil also containing approximately equal amounts of isoamyl alcohol and _/d_/-amyl alcohol ,marckwald1 #aijb1 whilst corn and potatoes1 in which leucine preponderates over isoleucine1 yield fusel oils containing a relatively large amount of the inactive alcohol4 ,the subject is1 in fact1 one of great interest to the technologist1 for as ,ehrlich points out the great variety of the bouquets of wine and aromas of brandy1 cognac1 arrak1 rum1 etc41 may be very simply referred to the manifold variety of the proteins of the raw materials 7grapes1 corn1 rice1 sugar cane1 etc47 from which they are derived4 ,yeast can also form fusel oil at the expense of its own protein1 but this only occurs to any considerable extent when the external p#jhi supply of nitrogen is insufficient4 ,under these circumstances the amino-acids formed by autolysis may be decomposed and their nitrogen employed over again for the construction of the protein of the cell4 ,the yield is also influenced by the condition of the yeast employed with regard to nitrogen1 a yeast poor in nitrogen being more efficacious in decomposing amino-acids than one which is already well supplied with nitrogenous materials4 ,the nature of the carbonaceous nutriment and finally the species of yeast are also of great importance see ,ehrlich1 #aiaa1 #b2 ,ehrlich and ,jacobsen1 #aiaa4 ,a very important characteristic of the action of yeast on the amino-acids is that the two stereo-isomerides of these optically active compounds are fermented at different rates4 ,when inactive1 racemic leucine is treated with yeast and sugar1 the naturally occurring component1 the _/l_/-leucine1 is more rapidly attacked1 so that if the experiment be interrupted at the proper moment the other component1 the _/d_/-leucine1 alone is present and may be isolated in the pure state4 ,in an actual experiment #ch grams of this component were obtained in the pure state from #aj grams of _/dl_/-leucine ,ehrlich1 #aijf1 #a1 so that the whole of the _/l_/-leucine 7#e grams7 had been decomposed but only #ab grams of the _/d_/-leucine4 ,this mode of action has been found to be characteristic of the alcoholic fermentation of the amino-acids by yeast4 ,in all the instances so far observed1 both components of the inactive amino-acid are attacked1 but usually the naturally occurring isomeride is the more rapidly decomposed1 although in the case of -aminobutyric acid both components disappear at the same rate ,ehrlich and ,wendel1 #aijh1 #a4 ,this reaction therefore must be classed along with the action of moulds on hydroxy-acids ,mc,kenzie and ,harden1 #aijc1 and the action of lipase on inactive esters ,dakin1 #aijc1 #aije1 in which both isomerides are attacked but at unequal rates1 and differs sharply from the action of yeast itself on sugars ,fischer and ,thierfelder1 #ahid1 and of emulsin1 maltase1 etc41 which only act on one isomeride and leave the other entirely untouched see ,bayliss1 #aiad1 pp4 #ee1 #gg1 #aag4 ,,succinic ,,acid4 ,the origin of the succinic acid formed in fermentation has also been traced by ,ehrlich #aiji to the alcoholic fermentation of the amino-acids4 ,it was shown by ,buchner and by ,kunz #aijf that succinic acid like fusel oil is not formed during fermentation by yeast-juice or zymin1 and1 in the light of ,ehrlich's work on fusel oil1 several p#jij modes of formation appeared possible for this substance ,ehrlich1 #aijf1 #c4 ,the dibasic amino-acids might1 for example1 undergo simple reduction1 the ,,nh#b group being removed as ammonia and replaced by hydrogen4 ,aspartic acid would thus pass into succinic acid3-- ,,cooh,,ch#b;,,ch7,,nh#b7;,,cooh #b;,h ,,cooh,,ch#b;,,ch#b;,,cooh ,,nh#c4 ,this change can be effected in the laboratory only by heating with hydriodic acid4 ,biologically it has been observed ,e4 and ,h4 ,salkowski1 #ahgi when aspartic acid is submitted to the action of putrefactive bacteria1 and almost quantitatively when _/,bacillus coli communis_/ is cultivated in a mixture of aspartic acid and glucose ,harden1 #aija4 ,in this case a well-defined source of hydrogen exists in the glucose1 which when acted on by this bacillus yields a large volume of gaseous hydrogen1 which is not evolved in the presence of aspartic acid4 ,some such source is also available in the case of yeast1 although it cannot be chemically defined1 for this organism is known to produce many reducing actions1 which are usually ascribed to the presence of reducing ferments or reductases in the cell4 ,a similar action would convert glutamic acid1 ,,cooh,,ch#b;,,ch#b;,,ch7,,nh7#b;,,cooh1 into glutaric acid1 ,,cooh,,ch#b;,,ch#b;,,ch#b;,,cooh1 which also is found among the products of fermentation1 whilst the monamino-acids would pass into the simple fatty acids4 ,on submitting these ideas to the test of experiment1 however1 ,erhlich found that the addition of aspartic acid did not in any way increase the yield of succinic acid1 and that of all the amino-acids which were tried only glutamic acid1 ,,cooh,,ch#b;,,ch#b;,,ch7,,nh#b7;,,cooh1 produced a definite increase in the amount of this substance4 ,further experiments showed that glutamic acid was actually the source of the succinic acid1 the relations being quite similar to those which exist for the production of fusel oil4 ,succinic acid is formed whenever sugar is fermented by yeast1 even in the absence of added nitrogenous matter1 and amounts to #jb to #jf per cent4 of the weight of the sugar decomposed1 its origin in this case being the glutamic acid formed by the autolysis of the yeast protein4 ,when some other source of nitrogen is present1 such as asparagine or an ammonium salt1 the amount falls to #jje to #ja4 ,if glutamic acid be added it rises to about #a to #ae per cent4 but falls again to about #jje to #ja when other sources of nitrogen1 such as asparagine or ammonium salts1 are simultaneously available1 either in the presence or p#jia absence of added glutamic acid4 ,as in the case of fusel oil1 the production does not occur in the absence of sugar1 and is not effected by yeast-juice or zymin4 ,the chemical reaction involved in the production of succinic acid differs to some extent from that by which fusel oil is formed1 inasmuch as an oxidation is involved3-- ,,cooh,,ch#b;,,ch,,ch7,,nh#b7;,,cooh #b,o ,,cooh,,ch#b;,,ch#b;,,cooh ,,nh#c ,,co#b4 ,from analogy with the production of amyl alcohol from leucine1 glutamic acid would be expected to yield -hydroxybutyric acid3-- ,,cooh,,ch#b;,,ch#b;,,ch7,,nh#b7;,,cooh ,h#b,o ,,nh#c ,,co#b ,,cooh,,ch#b;,,ch#b;,,ch#b,,oh4 ,as a matter of fact this substance cannot be detected among the products of fermentation1 but succinic acid as already explained is formed4 ,this acid might1 however1 possibly be formed by the oxidation of the -hydroxybutyric acid3-- ,,cooh,,ch#b;,,ch#b;,,ch#b,,oh #b,o ,,cooh,,ch#b;,,ch#b;,,cooh ,h#b,o1 although this change is on biological grounds improbable4 ,the conversion of the group ,,ch7,,nh#b7 into the terminal ,,ch#b,,oh in fusel oil1 or ,,cooh in succinic acid1 may possibly be effected in several different ways1 the most probable of which are the following3-- ,i4 ,direct elimination of carbon dioxide1 followed by hydrolysis of the resulting amine3-- 7#a7 ,r,,ch7,,nh#b7;,,cooh ,r,,ch#b,,nh#b ,,co#b4 7#b7 ,r,,ch#b,,nh#b ,h#b,o ,r,,ch#b,,oh ,,nh#c4 ,the reaction 7#a7 is actually effected by many bacteria and has been employed for the preparation of bases from amino-acids cf4 ,barger1 #aiad1 p4 #g1 although there is no direct evidence that it can be brought about by yeast4 ,on the other hand reaction 7#b7 has actually been observed with some yeasts4 ,thus it has been found ,ehrlich and ,pistschimuka1 #aiab1 #a that many wild yeasts produce this change with great readiness in presence of sugar1 glycerol or ethyl alcohol as sources of carbon and grow well in media in which amines1 such as p-hydroxyphenylethylamine or iso-amylamine1 form the only source of nitrogen4 _/,willia anomala_/ 7,hansen71 a yeast which forms surface growths1 succeeds admirably under these conditions1 whereas culture yeasts are much less active in this way1 although they produce a certain amount of change4 ,it is therefore possible that this mode of decomposition plays some part in the production of fusel oil1 but in the case of culture yeasts it is entirely subordinated to the mode next to be discussed4 p#jib ,,ii4 ,oxidative removal of the ,,nh#b group with formation of an -ketonic acid3-- 7#a7 ,r,,ch7,,nh#b7;,,cooh ,o ,r,,co,,cooh ,,nh#c followed by the decomposition of the ketonic acid into carbon dioxide and an aldehyde and the subsequent reduction or oxidation of the aldehyde3-- 7#b7 ,r,,co,,cooh ,r,,cho ,,co#b4 7#c7 7_/a_/7 ,r,,cho #b;,h ,r,,ch#b,,oh4 7_/b_/7 ,r,,cho ,o ,r,,cooh4 ,the evidence for the occurrence of reaction 7#a7 is supplied by the experiments of ,neubauer and ,fromherz #aiaa4 ,having previously found that amino-acids undergo a change of this kind in the animal body1 ,neubauer investigated their behaviour towards yeast4 ,taking _/dl_/-phenylaminoacetic acid1 ,c#f;,h#e;,,ch7,,nh#b7;,,cooh1 it was found that the changes produced were essentially the same as in the animal body4 ,the _/l_/-component of the acid was partly acetylated and partly unchanged1 whereas the _/d_/-component of the acid yielded benzyl alcohol1 ,c#f;,h#e;,,ch#b,,oh1 phenylglyoxylic acid1 ,c#f;,h#e;,,co,,cooh1 and the hydroxy-acid ,c#f;,h#e;,,ch7,,oh7,,cooh4 ,since however this hydroxy-acid was produced in the _/l_/-form it probably arose by the asymmetric reduction of phenylglyoxylic acid1 a reaction which can be effected by yeast as was also found to be the case in the animal body see ,dakin1 #aiab1 pp4 #eb1 #gh4 ,moreover it was shown that when the effects of yeast on a ketonic acid and the corresponding hydroxy-acid were compared1 the alcohol was formed in much better yield from the ketonic acid 7#gj per cent47 than from the hydroxy-acid 7#c-d per cent471 the actual example being the production of tyrosol 7p-hydroxyphenylethyl alcohol71 ,,oh,c#f;,h#d;,,ch#b;,,ch#b,,oh1 from p-hydroxyphenylpyruvic acid1 ,,oh,c#f;,h#d;,,ch#b;,,co,,cooh1 and p-hydroxyphenyl-lactic acid1 ,,oh,c#f;,h#d;,,ch#b;,,ch7,,oh7,,cooh respectively4 ,neubauer by these experiments established two extremely important points4 #a4 ,that the amino-acids actually yield the corresponding -ketonic acids when treated with yeast and sugar solution4 #b4 ,that the a-ketonic acids under similar conditions give the alcohol containing one carbon atom less in good yield1 whereas the corresponding hydroxy-acids only give an extremely small amount of these alcohols4 ,it is therefore probable that at an early stage in the decomposition of the amino-acids by yeast a ketonic acid is produced1 which then undergoes further change4 ,the source of the oxygen required for this reaction and the mechanism of oxidation have not yet been definitely ascertained4 ,it is possible p#jic ,,oh that hydrated imino-acids of the type ,r,c,,cooh are first formed ,,nh#b ,knoop1 #aiaj1 but these have not as yet been isolated4 ,the spontaneous production of ketonic aldehydes from amino-acids and from hydroxy-acids in aqueous solution1 which has been demonstrated by ,dakin and ,dudley #aiac1 points however to the possibility that the ketonic acid may be a secondary product derived from the corresponding ketonic aldehyde see also ,dakin1 #aijh2 ,neuberg1 #aijh1 #aiji4 ,this itself may either arise directly from the amino-acid or from a previously formed hydroxy-acid1 the latter alternative being1 however1 improbable in view of the small yield of alcohol obtained from hydroxy-acids by the action of yeast in the experiments of ,neubauer and ,fromherz4 ,r,,ch7,,nh#b7;,,cooh ,r,,ch7,,oh7,,cooh ,r,,ch7,,nh#b7;,,cooh ,r,,co,,cho ,r,,co,,cho ,r,,ch7,,oh7,,cooh #b,r,,co,,cho ,o#b #b,r,,co,,cooh 7#b7 ,whatever be the exact mode by which the ketonic acid is formed1 it appears most probable that a compound of this nature forms the starting-point for the next stage in the production of the alcohols4 ,the researches of ,neuberg1 which have already been discussed on p4 #ha1 have revealed a mechanism in yeast--the enzyme carboxylase--by which these -ketonic acids are rapidly broken up into an aldehyde and carbon dioxide3 ,r,,co,,cooh ,r,,cho ,,co#b and it can scarcely be doubted that this is the actual course of the reaction4 7#c7 ,the final conversion of the aldehyde into the corresponding alcohol is also a change which it has been proved can be effected by yeast ,neuberg and ,rosenthal1 #aiac probably by the aid of the reductase which is one of the weapons in its armoury of enzymes4 ,yeast is capable of producing many vigorous reducing actions and rapidly reduces methylene blue and sodium selenite4 ,it is in all probability due to a reaction of this kind that the iso-amylaldehyde and isovaleraldehyde were reduced to the alcohols in ,neuberg and ,steenbock's experiments #aiac1 #aiad1 and that considerable quantities of ethyl alcohol are formed in the sugar free fermentation of pyruvic acid ,neuberg and ,kerb1 #aiac1 #a 7see later p4 #aaj for a discussion of this question74 ,a further possibility exists that in some cases the aldehyde may p#jid be simultaneously oxidised and reduced or the molecule of one aldehyde reduced and that of another oxidised with production of the corresponding acid and alcohol by an aldehydo-mutase1 similar to that which has been observed by ,parnas #aiaj in many animal tissues4 ,finally the aldehyde may simply be converted into the corresponding acid by oxidation as appears to take place in the formation of succinic acid4 ,the intermediate production of an aldehyde would thus be consistent both with the production of alcohols and acids from amino-acids4 ,fusel oil would be formed by the reduction of the aldehydes arising from the simple monobasic amino-acids1 succinic acid would be produced by oxidation of the aldehyde derived from the dibasic glutamic acid4 ,in favour of this view is to be adduced the fact that aldehydes such as isobutyraldehyde and valeraldehyde have been found in crude spirit1 whilst acetaldehyde is a regular product of alcoholic fermentation see ,ashdown and ,hewitt1 #aiaj4 ,benzaldehyde1 moreover1 has been actually detected as a product of the alcoholic fermentation of phenylaminoacetic acid1 ,c#f;,h#e;,,ch7,,nh#b7;,,cooh ,ehrlich1 #aijg1 #a4 ,further1 the aldehydes so produced would readily pass by oxidation into the corresponding fatty acids1 small quantities of which are invariably produced in fermentation4 ,this view of the nature of the alcoholic fermentation of the amino-acids is undoubtedly to be preferred to that previously suggested by ,ehrlich #aijf1 #c according to which a hydroxy-acid is first formed and then either directly decomposed into an alcohol and carbon dioxide or into an aldehyde and formic acid1 the aldehyde being reduced and the formic acid destroyed 7see p4 #aae74 ,r,,ch7,,nh#b7;,,cooh ,r,,ch7,,oh7,,cooh ,r,,ch7,,oh7,,cooh ,r,,ch#b,,oh ,,co#b or ,r,,cho ,h,,co#b;,h ,r,,cho ,r,,ch#b,,oh ,the most probable course of the decomposition by which isoamyl alcohol and succinic acid are produced from leucine and glutamic acid respectively is therefore the following3-- 7_/a_/7 _/,isoamyl ,alcohol4_/ 7#a7 7,,ch#c7b;,,ch,,ch#b;,,ch7,,nh#b7;,,cooh 7#c7 7,,ch#c7b;,,chch#b;,,cho,,co#b ,leucine ,isovaleraldehyde 7#b7 7,,ch#c7b;,,ch,,ch#b;,,co,,cooh 7#d7 7,,ch#c7b;,,ch,,ch#b;,,ch#b,,oh -,ketoisovalerianic acid ,isoamyl alcohol 7_/b_/7 _/,succinic ,acid4_/ 7#a7 ,,cooh,,ch#b;,,ch#b;,,ch7,,nh#b7;,,cooh 7#c7 ,,cooh,,ch#b;,,ch#b;,,cho ,,co#b ,glutamic acid ,succinic semialdehyde 7#b7 ,,cooh,,ch#b;,,ch#b;,,co,,cooh 7#d7 ,,cooh,,ch#b;,,ch#b;,,cooh -,keto-glutaric acid ,succinic acid p#jie ,,glycerol4 ,of the three chief by-products of alcoholic fermentation1 only glycerol remains at present referable directly to the sugar4 ,this substance1 as shown by the careful experiments of ,buchner and ,meisenheimer #aijf1 is formed by the action both of yeast-juice and zymin to the extent of #ch per cent4 of the sugar decomposed1 and no other source for its production has so far been experimentally demonstrated4 ,if it be true that during the decomposition of sugar into alcohol and carbon dioxide1 substances containing three carbon atoms are formed as intermediate compounds 7see p4 #ajj71 it is obvious that these might by reduction be converted into glycerol which would thus be a true by-product of the alcoholic fermentation of sugar4 ,see ,oppenheimer1 #aiad1 #b4 ,it has1 however1 been suggested that it may in reality be a product of decomposition of lipoid substances or of the nuclein of the cell 7,ehrlich74 ,the effect of ,ehrlich's work has been clearly to distinguish the chemical changes involved in the production of fusel oil and succinic acid from those concerned in the decomposition of sugar into alcohol and carbon dioxide1 and to bring to light a most important series of reactions by means of which the yeast-cell is able to supply itself with nitrogen1 one of the indispensable conditions of life4 p#jif ,,chapter ,,viii4 ,,the ,,chemical ,,changes ,,involved ,,in ,,fermentation4 ,it has long been the opinion of chemists that the remarkable and almost quantitative conversion of sugar into alcohol and carbon dioxide during the process of fermentation is most probably the result of a series of reactions1 during which various intermediate products are momentarily formed and then used up in the succeeding stage of the process4 ,no very good ground can be adduced for this belief except the contrast between the chemical complexity of the sugar molecule and the comparative simplicity of the constitution of the products4 ,many attempts have1 however1 been made to obtain evidence of such a series of reactions1 and numerous suggestions have been made of probable directions in which such changes might proceed4 ,in making these suggestions1 investigators have been guided mainly by the changes which are produced in the hexoses by reagents of known composition4 ,the fermentable hexoses1 glucose1 fructose1 mannose1 and galactose1 appear to be relatively stable in the presence of dilute acids at the ordinary temperature1 and are only slowly decomposed at #ajj1 more rapidly by concentrated acids1 with formation of ketonic acids1 such as levulinic acid1 and of coloured substances of complex and unknown constitution4 ,in the presence of alkalis1 on the other hand1 the sugar molecule is extremely susceptible of change4 ,in the first place1 as was discovered by ,lobry de ,bruyn #ahie2 ,bruyn and ,ekenstein1 #ahie2 #ahif2 #ahig1 #a1 #b1 #c1 #d1 each of the three hexoses1 glucose1 fructose1 and mannose is converted by dilute alkalis into an optically almost inactive mixture containing all three1 and probably ultimately of the same composition whichever hexose is employed as the starting-point4 ,this interesting phenomenon is most simply explained on the assumption that in the aqueous solution of any one of these hexoses1 along with the molecules of the hexose itself1 there exists a small proportion of those of an enolic form which is common to all the three hexoses1 as illustrated by the following formul1 the aldehyde formul p#jig being employed instead of the -oxide formul for the sake of simplicity3-- ,,cho ,,cho ,,ch#b7,,oh7 ,,ch7,,oh7 ,,hcoh ,,hoch ,,co ,,coh ,,hoch ,,hoch ,,hoch ,,hoch ,,hcoh ,,hcoh ,,hcoh ,,hcoh ,,hcoh ,,hcoh ,,hcoh ,,hcoh ,,ch#b7,,oh7 ,,ch#b7,,oh7 ,,ch#b7,,oh7 ,,ch#b7,,oh7 ,glucose4 ,mannose4 ,fructose4 ,enolic form4 ,this enolic form is capable of giving rise to all three hexoses1 and the change by which the enolic form is produced and converted into an equilibrium mixture of the three corresponding hexoses is catalytically accelerated by alkalis1 or rather by hydroxyl ions4 ,in neutral solution the change is so slow that it has never been experimentally observed2 in the presence of decinormal caustic soda solution at #gj the conversion is complete in three hours4 ,precisely similar effects are produced with galactose1 which yields an equilibrium mixture containing talose and tagatose1 sugars which appear not to be fermentable4 ,the continued action even of dilute alkaline solutions carries the change much further and brings about a complex decomposition which is much more rapidly effected by more concentrated alkalis and at higher temperatures4 ,this change has been the subject of very numerous investigations for an account of these see ,e4 v4 ,lippmann1 #aijd1 pp4 #cbh1 #gac1 #hce1 but for the present purpose the results recently obtained by ,meisenheimer #aijh may be quoted as typical4 ,using normal solutions of caustic soda and concentrations of from #b to #e grams of hexose per #ajj c4c41 it was found that at air temperature in #bg to #aci days from #cj to #ed per cent4 of the hexose was converted into inactive lactic acid1 ,c#c;,h#f,o#c1 from #je to #b per cent4 into formic acid1 ,,ch#b,o#b1 and about #dj per cent4 into a complex mixture of hydroxy-acids1 containing six and four carbon atoms in the molecule4 ,usually only about #gd to #ij per cent4 of the sugar which had disappeared was accounted for1 but in one case the products amounted to #ig per cent4 of the sugar4 ,about #a per cent4 of the sugar was probably converted into alcohol and carbon dioxide4 ,no glycollic acid1 oxalic acid1 glycol1 or glycerol was produced4 ,the fact that alcohol is actually formed by the action of alkalis on sugar was established by ,buchner and ,meisenheimer #aije1 who obtained small quantities of alcohol 7#ah to #bh grams from #c kilos4 of cane sugar7 by acting on cane sugar with boiling concentrated caustic soda p#jih solution4 ,it is evident that under these conditions an extremely complex series of reactions occurs1 but the formation of alcohol and carbon dioxide and of a large proportion of lactic acid deserves more particular attention4 ,the direct formation of alcohol from sugar by the action of alkalis appears first to have been observed by ,duclaux #ahhf1 who exposed a solution of glucose and caustic potash to sunlight and obtained both alcohol and carbon dioxide4 ,as much as #bf per cent4 of the sugar was converted into alcohol in a similar experiment made by ,buchner and ,meisenheimer #aijd4 ,when the weaker alkalis1 lime water or baryta water1 were employed instead of caustic potash1 however1 no alcohol was formed1 but #ej per cent4 of the sugar was converted into inactive lactic acid ,duclaux1 #ahic1 #ahif4 ,duclaux therefore regarded the alcohol and carbon dioxide as secondary products of the action of a comparatively strong alkali on preformed lactic acid4 ,ethyl alcohol can1 in fact1 be produced from lactic acid both by the action of bacteria ,fitz1 #ahhj and of moulds ,maz1 #aijb1 and also by chemical means4 ,thus ,duclaux #ahhf found that calcium lactate solution exposed to sunlight underwent decomposition1 yielding alcohol and calcium carbonate and acetate1 whilst ,hanriot #ahhe1 #ahhf1 by heating calcium lactate with slaked lime obtained a considerable quantity of a liquid which he regarded as ethyl alcohol1 but which was shown by ,buchner and ,meisenheimer #aije to be a mixture of ethyl alcohol with isopropyl alcohol4 ,it appears1 therefore1 that inactive lactic acid can be quite readily obtained in large proportion from the sugars by the action of alkalis1 whilst alcohol can only be prepared in comparatively small amount and probably only as a secondary product of the decomposition of lactic acid4 ,the study of the action of alkalis on sugar has1 however1 yielded still further information as regards the mechanism of the reaction by which lactic acid is formed4 ,a considerable body of evidence has accumulated1 tending to show that some intermediate product of the nature of an aldehyde or ketone containing three carbon atoms is first formed4 ,thus ,pinkus #ahih and subsequently ,nef #aijd1 #aijg1 by acting on glucose with alkali in presence of phenylhydrazine obtained the osazone of methylglyoxal1 ,,ch#c;,,co,,cho4 ,this osazone may be formed either from methylglyoxal itself1 from acetol1 ,,ch#c;,,co,,ch#b,,oh1 or from lactic aldehyde1 ,,ch#c;,,ch7,,oh7,,cho ,wohl1 #aijh4 ,methylglyoxal itself may also be regarded as a secondary p#jii product derived from glyceraldehyde1 ,,ch#b7,,oh7,,ch7,,oh7,,cho1 or dihydroxyacetone1 ,,ch#b7,,oh7,,co,,ch#b7,,oh71 by a process of intramolecular dehydration1 so that the osazone might also be derived indirectly from either of these compounds see also ,neuberg and ,oertel1 #aiac4 ,methylglyoxal itself readily passes into lactic acid when it is treated with alkalis1 a molecule of water being taken up3-- ,,ch#c;,,co,,cho ,h#b,o ,,ch#c;,,ch7,,oh7,,cooh4 ,further evidence in the same direction is afforded by the interesting discovery of ,windaus and ,knoop #aije1 that glucose is converted by ammonia in presence of zinc hydroxide into methyliminoazole1 ,,ch#c;,c,,nh ,,ch1 ,,ch,n a substance which is a derivative of methylglyoxal4 ,the idea suggested by ,pinkus that acetol is the first product of the action of alkalis on sugar has been rendered very improbable by the experiments of ,nef1 and the prevailing view 7,nef1 ,windaus and ,knoop1 ,buchner and ,meisenheimer7 is that the first product is glyceraldehyde1 which then passes into methylglyoxal1 and finally into lactic acid3-- 7#a7 ,c#f;,h#ab,o#f #b;,,ch#b7,,oh7,,ch7,,oh7,,cho4 7#b7 ,,ch#b7,,oh7,,ch7,,oh7,,cho ,,ch#c;,,co,,cho ,h#b,o4 7#c7 ,,ch#c;,,co,,cho ,h#b,o ,,ch#c;,,ch7,,oh7,,cooh4 ,all these changes may occur at ordinary temperatures in the presence of a catalyst1 and in so far resemble the processes of fermentation by yeasts and bacteria4 ,the first attempt to suggest a scheme of chemical reactions by which the changes brought about by living organisms might be effected was made in #ahgj by ,baeyer #ahgj1 who pointed out that these decompositions might be produced by the successive removal and re-addition of the elements of water4 ,the result of this would be to cause an accumulation of oxygen atoms towards the centre of the chain of six carbon atoms1 which1 in accordance with general experience1 would render the chain more easily broken4 ,baeyer formulated the changes characteristic of the alcoholic and lactic fermentations as follows1 the intermediate stages being derived from the hydrated aldehyde formula of glucose by the successive removal and addition of the elements of water3 p#ajj ,i4 ,,ii4 ,,iii4 ,,iv4 ,v4 ,,ch#b,,oh ,,ch#b444,,oh ,,ch#c ,,ch#c ,,ch#c ,,ch,,oh ,,coh44,h ,,ch,,oh ,,ch7,,oh7 ,,ch#b ,,ch,,oh ,c44,,oh44,h ,c7,,oh7#b ,,co ,o ,,ch,,oh ,,coh444,h ,c7,,oh7#b ,o ,,co ,,ch,,oh ,,coh444,h ,c7,,oh7#b ,,co ,o ,,ch7,,oh7#b ,,ch4447,,oh7#b ,,ch#c ,,ch7,,oh7 ,,co ,,ch#c ,o ,,ch#b ,,ch#c ,the immediate precursor of alcohol and carbon dioxide is here seen to be the anhydride of ethoxycarboxylic acid 7,v71 whilst that of lactic acid is lactic anhydride 7,,iv74 7,baeyer does not appear1 as recently stated by ,meisenheimer #aijg1 p4 #h1 ,wohl #aijg1 #b1 and ,buchner and ,meisenheimer #aiji to have suggested that lactic acid was an intermediate product in alcoholic fermentation1 but rather to have represented independently the course of the two different kinds of fermentation1 the alcoholic and the lactic47 ,it was subsequently pointed out by ,buchner and ,meisenheimer #aijd that ,baeyer's principle of oxygen accumulation might be applied in a different way1 so that a ketonic acid would be produced1 the decomposition of which1 in a manner analogous to that of acetoacetic acid1 would lead to the formation of two molecules of lactic acid1 from which the final products alcohol and carbon dioxide might be directly derived1 as shown in the following formul3-- ,,cho ,,cooh ,,cooh ,,co#b ,,ch7,,oh7 ,,ch7,,oh7 ,,ch7,,oh7 ,,ch#b,,oh ,,ch7,,oh7 ,,ch#b ,,ch#c ,,ch#c ,,ch7,,oh7 ,,co ,,cooh ,,co#b ,,ch7,,oh7 ,,ch7,,oh7 ,,ch7,,oh7 ,,ch#b,,oh ,,ch#b7,,oh7 ,,ch#c ,,ch#c ,,ch#c ,a scheme based on somewhat different principles has been propounded by ,wohl ,lippmann1 #aijd1 p4 #ahia1 and has been accepted by ,buchner and ,meisenheimer #aije as more probable than that quoted above4 ,wohl and ,oesterlin #aija were able to trace experimentally the various stages of the conversion of tartaric acid 7,i7 into oxalacetic acid 7,,iii71 which can be carried out by reactions taking place at the ordinary temperature1 and they found that the first stage consisted in the removal of the elements of water leaving an unsaturated hydroxy derivative 7,,ii7 which in the second stage underwent intramolecular change into the corresponding keto-compound 7,,iii73 p#aja ,,cooh ,,cooh ,,cooh ,,ch7,,oh7 minus ,h ,c7,,oh7 ,,co ,,ch7,,oh7 ,,oh ,,ch ,,ch#b ,,cooh ,,cooh ,,cooh ,i4 ,,ii4 ,,iii4 ,tartaric acid4 ,oxalacetic acid4 ,this change differs in principle from that assumed by ,baeyer1 inasmuch as the second stage is not effected by the re-addition of water1 but by the keto-enol transformation1 which is now usually ascribed to the migration of the hydrogen atom1 although the same result can theoretically be arrived at by the addition and removal of the elements of water4 ,the analogy of this process to what might be supposed to occur in the conversion of sugar into carbon dioxide and alcohol was pointed out by ,wohl and ,oesterlin1 and subsequently ,wohl developed a theoretical scheme of reactions by which the process of alcoholic fermentation could be represented4 ,in the first place the elements of water are removed from the and carbon atoms of glucose 7,i7 and the resulting enol 7,,ii7 undergoes conversion into the corresponding ketone 7,,iii71 which has the constitution of a condensation product of methylglyoxal and glyceraldehyde1 and hence is readily resolved by hydrolysis into these compounds 7,,iv74 ,the glyceraldehyde passes by a similar series of changes 7,v1 ,,vi7 into methylglyoxal1 and this is then converted by addition of water into lactic acid 7,,vii71 a reaction which is common to all ketoaldehydes of this kind4 ,finally1 the lactic acid is split up into alcohol and carbon dioxide 7,,viii73-- ,,cho ,,cho ,,cho ,,ch7,,oh7 ,h ,c7,,oh7 ,,co minus ,,ch7,,oh7 ,,oh ,,ch ,,ch#b ,,ch7,,oh7 ,,ch7,,oh7 ,,ch7,,oh7 ,,ch7,,oh7 ,,ch7,,oh7 ,,ch7,,oh7 ,,ch#b7,,oh7 ,,ch#b7,,oh7 ,,ch#b7,,oh7 ,i4 ,,ii4 ,,iii4 ,glucose4 ,methylglyoxal ,,cho ,,cooh ,,co#b ------ ,,co ,h#b,o ,,ch7,,oh7 ,,ch#b,,oh ,,ch#c ,,ch#c ,,ch#c ,,cho ,,cho ,,cho ,,cooh ,,co#b ,h ------ ,,ch7,,oh7 minus ,c7,,oh7 ,,co ,h#b,o ,,ch7,,oh7 ,,ch#b,,oh ,,oh ,,ch#b7,,oh7 ,,ch#b ,,ch#c ,,ch#c ,,ch#c ,,iv4 ,v4 ,,vi4 ,,vii4 ,,viii4 ,glyceraldehyde4 ,methyl- ,lactic ,alcohol glyoxal4 acid4 and carbon dioxide4 p#ajb ,this scheme agrees well with the current ideas as to the formation of lactic acid from glucose under the influence of alkalis 7p4 #ii74 ,it postulates the formation as intermediate products of no less than three compounds containing a chain of three carbon atoms--glyceraldehyde1 methylglyoxal1 and lactic acid4 ,,the ,,lactic ,,acid ,,theory ,,of ,,alcoholic ,,fermentation4 ,a practical interest was given to these various schemes by the fact that ,buchner and ,meisenheimer adduced experimental evidence in favour of the view that lactic acid is an intermediate product in the formation of alcohol and carbon dioxide from sugar by fermentation #aijd1 #aije1 #aijf1 #aiji4 ,these observers proved by a series of very careful analyses that yeast-juice frequently1 but not invariably1 contains small quantities of lactic acid1 not exceeding #jb per cent4 ,when yeast-juice is incubated alone or with sugar the amount of lactic acid may either increase or decrease4 ,moreover1 lactic acid added to the juice is sometimes diminished and sometimes increased in quantity4 ,on the whole it appears that the addition of a considerable quantity of sugar or of some lactic acid favours the disappearance of lactic acid4 ,juices of low fermenting power produce a diminution in the lactic acid present1 those of high fermenting power an increase4 ,in all cases the amounts of lactic acid either produced or destroyed are very small in relation to the volume of the yeast-juice employed4 ,throughout the whole series of experiments the greatest increase amounted to #jdg per cent4 on the juice employed1 and the greatest decrease to #jc per cent4 ,see also ,oppenheimer1 #aiad1 #a4 ,buchner and ,meisenheimer at one time regarded these facts as strong evidence that lactic acid is an intermediate product of alcoholic fermentation4 ,it was thought probable that the production of alcohol and carbon dioxide from sugar occurred in at least two stages and under the influence of two distinct enzymes4 ,the first stage consisted in the conversion of sugar into lactic acid1 and for the enzyme which brought about this decomposition was reserved the name zymase or yeast-zymase4 ,the lactic acid was then broken down into alcohol and carbon dioxide by the second enzyme1 lactacidase4 ,this theory1 which is quite in harmony with the current ideas as to the mode of decomposition of sugars by alkalis1 and is also consistent with ,wohl's scheme of reactions1 is open to adverse criticism from several points of view4 ,in the first place1 it is noticeable that the total amount of lactic acid used up by the juice is extremely small1 even p#ajc in the most favourable cases1 relatively to the amount of the juice ,harden1 #aije1 and it may be added to the sugar-fermenting power of the juice4 ,moreover1 as pointed out by ,buchner and ,meisenheimer themselves #aiji1 no proof is afforded that the lactic acid which disappears is converted into alcohol and carbon dioxide4 ,it is not even certain1 although doubtless probable1 that the lactic acid which occurs or is produced in the juice is really derived from sugar4 ,the most weighty criticism of the theory is that of ,slator #aijf1 #aijg2 #aijh1 #a1 #b1 which is based on the consideration that if lactic acid be an intermediate product of alcoholic fermentation the reaction by which it is fermented must proceed at least as rapidly as that by which it is formed1 in order to prevent accumulation of lactic acid4 ,the fermentation of lactic acid by yeast should therefore proceed at least as rapidly as that of glucose4 ,so far is that from being the case that it has been experimentally demonstrated that lactic acid is not fermented at all by living yeast4 ,this conclusion was rendered extremely probable by ,slator1 who showed that lactic acid1 even in concentrations insufficient to prevent the fermentation of glucose1 is not fermented to any considerable extent4 ,the final proof that lactic acid is neither formed nor fermented by pure yeast has been brought by ,buchner and ,meisenheimer in a series of very careful quantitative experiments carried out with a pure yeast and with strict precautions against bacterial contamination #aiji1 #aiaj4 ,at first sight this fact appears decisive against the validity of the lactic acid theory1 and it is recognised as such by ,buchner and ,meisenheimer4 ,wohl has1 however1 suggested that the non-fermentability of lactic acid by yeast is not really conclusive #aijg1 #a2 see also ,franzen and ,steppuhn1 #aiab1 #a4 ,the production of lactic acid from glucose is attended by the evolution of a considerable amount of heat 7#bb cal471 and it is possible that at the moment of production the molecule of the acid is in a condition of activity corresponding with a much higher temperature than the average temperature of the fermenting liquid4 ,under these circumstances the molecule would be much more susceptible of chemical change than at a later period when temperature equilibrium had been attained4 ,it has1 however1 been pointed out by ,tafel #aijg1 that such a decomposition of the lactic acid would occur at the very instant of formation of the molecule1 so that no ground remains even on this view for assuming the actual existence of lactic acid as a definite intermediate product4 ,it has also been suggested by ,luther #aijg that an unknown isomeride of lactic acid is formed as an intermediate product and fermented1 and that traces of lactic p#ajd acid are formed by a secondary reaction from this1 but no satisfactory evidence for this view is forthcoming4 ,there still remains a doubt as to whether the living yeast-cell is permeable to lactic acid1 a fact which would of course afford a very simple explanation of the non-fermentability of the acid4 ,apart from this1 however1 it is difficult1 in face of the evidence just quoted1 to believe that lactic acid is in reality an intermediate product in alcoholic fermentation4 ,,methylglyoxal1 ,,dihydroxyacetone ,,and ,,glyceraldehyde4 ,as regards the fermentability by yeast of compounds containing three carbon atoms1 which may possibly appear as intermediate products in the transformation of sugar into carbon dioxide and alcohol1 many experiments have been carried out1 with somewhat uncertain results4 ,care has to be taken that the substance to be tested is not added in such quantity as to inhibit the fermenting power of the yeast or yeast-juice1 and further that the conditions are such that the substance in question1 often of a very unstable nature1 is not converted by some chemical change into a different fermentable compound4 ,it is also possible that the substance to be tested may accelerate the rate of autofermentation in a similar manner to arsenates 7pp4 #hj1 #abf7 and many other substances4 ,these are all points which have not up to the present received sufficient attention4 ,in the case of living yeast the further question arises of the permeability of the cell4 ,methylglyoxal1 ,,ch#c;,,co,,cho1 has been tested by ,mayer #aijg and ,wohl #aijg1 #b with yeast1 and by ,buchner and ,meisenheimer both with acetone-yeast #aijf and yeast-juice #aiaj1 in every case with negative results1 but it may be noted that the concentration employed in the last mentioned of these experiments was such as considerably to diminish the autofermentation of the juice4 ,glyceraldehyde1 ,,ch#b7,,oh7,,ch7,,oh7,,cho1 was also tested with yeast with negative results by ,wohl #ahih and by ,emmerling #ahii1 who employed a number of different yeasts4 ,the same negative result attended the experiments of ,piloty #ahig and ,emmerling #ahii with pure dihydroxyacetone4 ,fischer and ,tafel #ahhh1 #ahhi1 however1 had previously found that glycerose1 a mixture of glyceraldehyde and dihydroxyacetone prepared by the oxidation of glycerol1 was readily fermented by yeast1 agreeing in this respect with the still older observations of ,van ,deen and of ,grimaux4 ,the reason for this diversity of result has not been definitely ascertained1 but it has been supposed by ,emmerling to lie in the formation of some fermentable sugar from p#aje glycerose when the latter is subjected to too high a temperature during its preparation4 ,on the other hand1 ,bertrand #aijd succeeded in fermenting pure dihydroxyacetone by treating a solution of #a gram in #cj c4c4 of liquid with a small quantity of yeast for ten days at #cj1 the best result being a fermentation of #be per cent4 of the substance taken4 ,moreover1 ,boysen-,jensen #aijh1 #aiaj1 #aiad states that he has also observed both the formation from glucose and the fermentation of this substance by living yeast1 but the amounts of alcohol and carbon dioxide produced were so minute and the evidence for the production of dihydroxyacetone so inconclusive that the experiments cannot be regarded as in any way decisive see ,chick1 #aiab2 ,euler and ,fodor1 #aiaa2 ,karauschanoff1 #aiaa2 ,buchner and ,meisenheimer1 #aiab4 ,a careful investigation by ,buchner #aiaj and ,buchner and ,meisenheimer #aiaj has led them to the conclusion that both glyceraldehyde and dihydroxyacetone are fermentable4 ,glyceraldehyde exerts a powerful inhibiting action both on yeast and yeast-juice1 and was only found to give rise to a very limited amount of carbon dioxide1 quantities of #jae to #jjbe gram being treated with #a gram of yeast or #e c4c4 of yeast-juice and a production of #d to #ab c4c4 of carbon dioxide being attained4 ,when #ja gram of dihydroxyacetone in #e c4c4 of water was brought in contact with #a gram of living yeast1 about half was fermented1 #ag c4c4 of carbon dioxide 7at #bj and #fjj mm47 being evolved in excess of the autofermentation of the yeast 7#ac c4c474 ,a much greater effect was obtained by the aid of yeast-juice1 and the remarkable observation was made that whilst yeast-juice alone produced comparatively little action a mixture of yeast-juice and boiled yeast-juice was much more effective1 quantities of #bj to #ej c4c4 of yeast-juice mixed with an equal volume of boiled juice1 which in some experiments was concentrated1 yielding with #jd1 #a1 and #b grams of dihydroxyacetone almost the theoretical amount of carbon dioxide and alcohol in excess of that evolved in the absence of this substance4 ,it was further observed that the fermentation of this substance commenced much more slowly than that of glucose4 ,no explanation of either of these facts has at present been offered4 ,the conclusion drawn from their experiments by ,buchner and ,meisenheimer that dihydroxyacetone is readily fermentable1 was confirmed by ,lebedeff #aiaa1 #a1 who further made the important observation that during the fermentation of dihydroxyacetone the same hexosephosphoric acid is produced as is formed during the fermentation of the hexoses4 ,lebedeff accordingly propounded a scheme of alcoholic fermentation according to which the hexose p#ajf was first converted into two molecules of triose1 the latter being first esterified to triosephosphoric acid and then condensed to hexosediphosphoric acid1 which then underwent fermentation1 after being hydrolysed to phosphoric acid1 and some unidentified substance1 probably an unstable modification of a hexose1 much more readily attacked by an appropriate enzyme than the original glucose or fructose #aiaa1 #a1 pp4 #bida-b4 ,the idea that the sugar is first converted into triose and this into triosemonophosphoric acid had been previously suggested by ,iwanoff who postulated the agency of a special enzyme termed _/synthease_/ #aiji1 #a1 and supposed that this triosemonophosphoric acid was then directly fermented to alcohol1 carbon dioxide and phosphoric acid4 ,according both to ,iwanoff and ,lebedeff the phosphoric ester is an intermediate product and its decomposition provides this sole source of carbon dioxide and alcohol4 ,this is quite inconsistent with the facts recounted above 7,chap4 ,,iii71 which prove that the formation of the hexosephosphate is _/accompanied_/ by an amount of alcoholic fermentation exactly equivalent to the quantity of hexosephosphate produced1 and that the rate of fermentation rapidly falls as soon as the free phosphate has disappeared1 in spite of the fact that at that moment the concentration of the hexosephosphate is at its highest1 whereas according to ,iwanoff's theory it is precisely under these conditions that the maximum rate of fermentation should be maintained4 ,it has also been shown that the arguments adduced by ,iwanoff in favour of the existence of his synthease are not valid ,harden and ,young1 #aiaj1 #a4 ,the fermentation of dihydroxyacetone was moreover proved by ,harden and ,young #aiab to be effected by yeast-juice and maceration extract at a much slower rate than that of the sugars1 in spite of the fact that the addition of dihydroxyacetone did not inhibit the sugar fermentation4 ,the same thing has been shown for living yeast by ,slator #aiab in agreement with the earlier results of ,buchner #aiaj and ,buchner and ,meisenheimer #aiaj4 ,the logical conclusion from ,lebedeff's experiments would appear rather to be that dihydroxyacetone is slowly condensed to a hexose and that this is then fermented in the normal manner ,harden and ,young1 #aiab2 ,buchner and ,meisenheimer1 #aiab2 ,kostytscheff1 #aiab1 #b4 ,buchner and ,meisenheimer1 however1 regard this as improbable on the ground that dihydroxyacetone1 being symmetric in constitution1 would yield an inactive hexose of which only at most #ej per cent4 would be fermentable4 ,against this it may be urged1 however1 p#ajg that enzymic condensation of dihydroxyacetone might very probably occur asymmetrically yielding an active and completely fermentable hexose4 ,buchner and ,meisenheimer1 however1 still support the view that dihydroxyacetone forms an intermediate stage in the fermentation of glucose and adduce as confirmatory evidence of the probability of such a change the observation of ,fernbach #aiaj that this compound is produced from glucose by a bacillus1 ,tyrothrix tenuis1 which effects the change both when living and after treatment with acetone4 ,the balance of evidence1 however1 appears to be in favour of the opinion that dihydroxyacetone does not fulfil the conditions laid down by ,slator 7see p4 #ajc7 as essential for an intermediate product in the process of fermentation see also ,lb1 #aiaj4 ,lebedeff subsequently #aiab1 #d2 ,lebedeff and ,griaznoff1 #aiab extended his experiments to glyceraldehyde and modified his theory very considerably4 ,using maceration extract it was found in general agreement with the results of ,buchner and ,meisenheimer 7p4 #aje7 that #bj c4c4 of juice were capable of producing about half the theoretical amount of carbon dioxide from #jb gram of glyceraldehyde1 whereas #jd gram caused coagulation of the extract and a diminished evolution of carbon dioxide4 ,the addition of phosphate diminished rather than increased the fermentation4 ,even in the most favourable concentration however 7#jb gram per #bj c4c47 the glyceraldehyde is fermented much more slowly than dihydroxyacetone or saccharose1 as is shown by the following figures3-- #bj c4c4 ,extract ,,co#b in grams in ,duration ,total #jb gram4 successive periods of of fermen- ,,co#b4 #f hours4#ah hours4#bd hours4 tation4 ,cane sugar #jjej #jjjj #jjjj #f #jje ,dihydroxyacetone #jjdb #jjjj #jjjj #f #jjdb ,glyceraldehyde #jjjh #jjbb #jjje #dh #jjce ,further1 during an experiment in which #jabi gram of ,,co#b was evolved in #bbe hours from #ji gram of glyceraldehyde in presence of phosphate1 no change in free phosphate was observed1 whereas in a similar experiment with glucose a loss of about #jb gram of ,p#b,o#e would have occurred4 ,hence the fermentation takes place without formation of hexosediphosphate4 ,this was confirmed by the fact that the osazone of hexosephosphoric acid was readily isolated from the products of fermentation of dihydroxyacetone 7#jbei gram of ,,co#b having been evolved in twenty hours7 but could not be obtained from those of glyceraldehyde 7#jach gram ,,co#b in twenty hours74 p#ajh ,this result is extremely interesting1 although it is not impossible that the rate of fermentation of the glyceraldehyde is so slow that any phosphoric ester produced is hydrolysed as rapidly as it is formed4 ,lebedeff regards the experiments as proof that phosphate takes no part in the fermentation of glyceraldehyde and bases on this conclusion and his other work the following theory of alcoholic fermentation4 #a4 ,the sugar is split up into equimolecular proportions of glyceraldehyde and dihydroxyacetone3-- 7a7 ,c#f;,h#ab,o#f ,c#c;,h#f,o#c ,c#c;,h#f,o#c4 #b4 ,the dihydroxyacetone then passes through the stages previously postulated 7p4 #ajf74 7b7 #d ,c#c;,h#f,o#c #d ,r#b;,,hpo#d #d ,c#c;,h#e,o#b,,po#d,r#b #d ,h#b,o4 7c7 #d ,c#c;,h#e,o#b,,po#d,r#b #b ,c#f;,h#aj,o#d7,r#b,,po#d7b4 7d7 #b ,c#f;,h#aj,o#d7,r#b,,po#d7b #d ,h#b,o #b ,c#f;,h#ab,o#f #d ,r#b;,,hpo#d4 ,after which the hexose1 ,c#f;,h#ab,o#f re-enters the cycle at 7a74 #c4 ,the fermentation of the glyceraldehyde occurs according to the scheme developed by ,kostytscheff 7p4 #aji71 pyruvic acid being formed along with hydrogen and then decomposed into carbon dioxide and acetaldehyde1 which is reduced by the hydrogen4 ,lebedeff1 however1 suggests #aiad1 #a1 #b that glyceric acid is first formed 7#a7 and then converted by an enzyme1 which he terms _/dehydratase_/ into pyruvic acid 7#b73-- 7#a7 ,,ch#b7,,oh7,,ch7,,oh7,,cho ,h#b,o ,,ch#b7,,oh7,,ch7,,oh7,,ch7,,oh7#b ,,ch#b7,,oh7,,ch7,,oh7,,ch7,,oh7#b ,,ch#b7,,oh7,,ch7,,oh7,,cooh #b;,h 7#b7 ,,ch#b7,,oh7,,ch7,,oh7,,cooh ,,ch#c;,,co,,cooh ,h#b,o4 ,the experimental basis for this idea is the fact that glyceric acid is fermented by dried yeast and maceration juice compare ,neuberg and ,tir1 #aiaa4 ,this scheme has the merit of recognising the fact that the carbon dioxide does not wholly arise from the products of decomposition of hexosephosphate1 nor from its direct fermentation4 ,the function assigned to the phosphate is that of removing dihydroxyacetone and thus preventing it from inhibiting further conversion of hexose into triose1 according to the reversible reaction ,c#f;,h#ab,o#f #b ,c#c;,h#f,o#c4 ,this however appears to be quite inadequate1 since1 on the one hand1 the fermentation of glucose proceeds quite freely in presence of as much as #e grams per #ajj c4c4 of dihydroxyacetone ,harden and ,young1 #aiab1 and on the other hand alcoholic fermentation appears not to proceed at all in the absence of phosphate 7see p4 #ee74 ,this forms the chief objection to the theory in its present form4 ,the slow rate at which p#aji glyceraldehyde is fermented also affords an argument against the validity of ,lebedeff's view1 but this may possibly be accounted for to some extent by the fact that glyceraldehyde is a strong inhibiting agent so that it might be more rapidly fermented if added in a more dilute condition4 ,the unfermented glyceraldehyde cannot be recovered from the solution and nothing is known as to its fate except that it readily gives rise both to lactic acid and glycerol ,oppenheimer1 #aiad1 #a1 #b4 ,evidently the reaction between glyceraldehyde and yeast-juice is by no means a simple one4 ,,the ,,pyruvic ,,acid ,,theory4 ,the third stage of ,lebedeff's theory postulates the intermediate formation of pyruvic acid4 ,this idea immediately suggested itself when it became known that yeast was capable of rapidly decomposing _/a_/-ketonic acids with evolution of carbon dioxide see ,neubauer and ,fromherz1 #aiaa1 p4 #cej2 ,neuberg and ,kerb1 #aiab1 #d2 ,kostytscheff1 #aiab1 #b4 ,this scheme has been differently elaborated by different workers4 ,according to ,kostytscheff it involves 7#a7 the production of pyruvic acid from the hexoses1 a process accompanied by loss of hydrogen2 7#b7 the decomposition of pyruvic acid into acetaldehyde and carbon dioxide2 and 7#c7 the reduction of the acetaldehyde to ethyl alcohol4 7#a7 ,c#f;,h#ab,o#f #b;,,ch#c;,,co,,cooh #d;,h4 7#b7 #b;,,ch#c;,,co,,cooh #b;,,ch#c;,,cho #b;,,co#b4 7#c7 #b;,,ch#c;,,cho #d;,h #b;,,ch#c;,,ch#b,,oh4 #a4 ,as regards the production of pyruvic acid from the hexoses by yeast1 the only direct evidence is afforded by the experiments of ,fernbach and ,schoen #aiac who have obtained a calcium salt having the qualitative properties of a pyruvate by carrying out alcoholic fermentation by yeast in presence of calcium carbonate1 but have not yet definitely settled either the identity of the acid or its origin from sugar4 ,pyruvic acid is1 however1 very closely related to several substances which are intimately connected both chemically and biochemically with the hexoses4 ,thus lactic acid is its reduction product1 ,,ch#c;,,co,,cooh ,,ch#c;,,ch7,,oh7,,cooh1 #b;,h glyceraldehyde can readily be converted into it by oxidation to glyceric acid followed by abstraction of water 7,erlenmeyer71 p#aaj ,,ch#b7,,oh7,,ch7,,oh7,,cho ,,ch#b7,,oh7,,ch7,,oh7,,cooh ,,ch#c;,,co,,cooh1 ,o ,h#b,o and finally methylglyoxal ,,ch#c;,,co,,cho is its aldehyde4 #b4 ,the decomposition of pyruvic acid into acetaldehyde and carbon dioxide has already been fully discussed 7,chapter ,,vi74 ,the universality of the enzyme carboxylase in yeasts and the rapidity of its action on pyruvic acid form the strongest evidence at present available in favour of the pyruvic acid theory4 ,given the pyruvic acid1 there is no doubt that yeast is provided with a mechanism capable of decomposing it at the same rate as an equivalent amount of sugar4 #c4 ,the final step postulated by the pyruvic acid theory is the quantitative reduction to ethyl alcohol of the acetaldehyde formed from the pyruvic acid4 ,the idea that acetaldehyde is an intermediate product in the various fermentations of sugar has frequently been entertained ,magnus ,levy1 #aijb2 ,leathes1 #aijf2 ,buchner and ,meisenheimer1 #aijh2 ,harden and ,norris1 ,d41 #aiab although no very definite experimental foundation exists for the belief4 ,it is1 however1 a well-known fact that traces of acetaldehyde are invariably formed during alcoholic fermentation see ,ashdown and ,hewitt1 #aiaj1 and this is of course consistent with the occurrence of acetaldehyde as an intermediate product4 ,important evidence as to the specific capability of yeast to reduce acetaldehyde to alcohol has been obtained by several workers4 ,thus ,kostytscheff #aiab1 #c2 ,kostytscheff and ,hbbenet1 #aiac found that pressed yeast1 dried yeast and zymin all reduced acetaldehyde to alcohol1 #ej grams of yeast in #aj hours producing from #ffj mg4 of aldehyde #bfe mg4 of alcohol in excess of the amount produced by autofermentation in absence of added aldehyde4 ,maceration extract was found to reduce both in absence and in presence of sugar1 whereas ,lebedeff and ,griaznoff #aiab obtained no reduction in presence of sugar1 and observed that the power of reduction was lost by the extract on digestion1 a circumstance which suggests the co-operation of a co-enzyme in the process4 ,neuberg and ,kerb #aiab1 #d2 #aiac1 #a have also been able to show by large scale experiments that alcohol is produced in considerable quantity by the fermentation of pyruvic acid by living yeast in absence of sugar and that the yield is increased by the presence of glycerol4 ,when treated with #bb kilos1 of yeast1 #a kilo1 of pyruvic acid yielded #bda grams of alcohol in excess of that given by the yeast alone1 whilst in presence of glycerol the amount was #cfj grams1 the amount theoretically obtainable being #ebc grams4 ,the function of the glycerol is not understood but is probably that of lessening the rate of destruction of the yeast enzymes4 p#aaa ,that yeast possesses powerful reducing properties has long been known and many investigations have been made as to the relation of these properties to the process of alcoholic fermentation4 ,thus ,hahn 7,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 p4 #cdc7 found that the power of reducing methylene blue was possessed both by yeast and zymin and on the whole ran parallel to the fermenting power in the process of alcoholic fermentation4 ,the intervention of a reducing enzyme was suggested by ,grss #aijd1 #aijh1 #a1 #b and was supported by ,palladin #aijh4 ,the latter observed that zymin which reduces sodium selenite and methylene blue in absence of sugar almost ceases to do so in presence of a fermentable sugar1 and concluded that the great diminution of reduction during fermentation was due to the fact that the reducing enzyme was largely combined with a different substrate arising from the sugar1 the reduction of which was necessary for alcoholic fermentation4 ,grss1 however1 found that with living yeast the reduction is greatly increased in presence of a fermentable sugar1 while ,harden and ,norris1 ,r4 ,v4 #aiad confirmed the observation of ,grss1 but found that the reducing power of zymin is not seriously affected by the presence of a fermentable sugar in concentration less then #bj grams per #ajj c4c41 whilst its fermenting power for glucose is inhibited by #a per cent4 sodium selenite4 ,hence ,palladin's conclusion cannot be regarded as proved4 ,interesting attempts have been made by ,kostytscheff and later by ,lvoff to obtain evidence of the participation of a reductase in alcoholic fermentation by adding some substance which would be capable either of taking up hydrogen and thus preventing the reduction of the acetaldehyde or of converting the aldehyde into some compound less liable to reduction4 ,kostytscheff #aiab1 #a2 #aiac1 #a1 #b2 #aiad2 ,kostytscheff and ,hbbenet1 #aiac2 ,kostytscheff and ,scheloumoff1 #aiac2 ,kostytscheff and ,brilliant1 #aiac has examined the effect of the addition of zinc chloride1 chosen with the idea that it might polymerise the aldehyde and thus remove it from the sphere of action4 ,as pointed out by ,neuberg and ,kerb #aiab1 #a this action is not very probable1 and it was subsequently found ,kostytscheff and ,scheloumoff1 #aiac that the effect of added zinc salts was more probably specifically due to the zinc ion4 ,fermentation of sugar by dried yeast still proceeds when #jf gram of ,zn,cl#b is added to #aj grams of the yeast and #ej c4c4 of water1 whereas it ceases in the presence of #ab gram of ,zn,cl#b4 ,even the addition of #jjge gram however greatly diminishes the rate of fermentation and the total amount of sugar decomposed4 ,the most noteworthy effect is that the production of acetaldehyde is increased both in autofermentation and p#aab in sugar fermentation4 ,the course of the reaction is further modified in the sense that the percentage of sugar used up which can be accounted for in the products decreases1 in other words the disappearing sugar 7p4 #ca7 increases4 ,in long continued fermentations moreover and particularly with high concentrations of zinc chloride less alcohol is produced than is equivalent to the carbon dioxide evolved4 ,the interpretation of these results is difficult4 ,kostytscheff takes them to mean 7#a7 that the zinc salt modifies one stage of the reaction so that a higher concentration of intermediate products is obtained1 and 7#b7 that the carbon dioxide and alcohol must be produced at different stages or their ratio1 in the absence of secondary changes1 would be unalterable4 ,alternative interpretations are1 however1 by no means excluded4 ,thus ,neuberg and ,kerb #aiab1 #a2 #aiac1 #b do not regard it as conclusively proved that the aldehyde really arises from the sugar since they have observed its production in maceration extract free from autofermentation4 ,the method used by ,kostytscheff for the separation of alcohol and aldehyde 7treatment with bisulphite7 has also proved unsatisfactory in their hands and the results obtained as to the reduction of acetaldehyde by yeast1 etc41 are not accepted4 ,they also consider that in any case the small amounts produced 7less than #jb per cent4 of the sugar used7 would not afford convincing evidence that the aldehyde is an intermediate product1 although it must be admitted that no large accumulation of an intermediate product could be reasonably expected4 ,it may also be pointed out that the increase in disappearing sugar may be simply due to the fact that in the controls the whole of the sugar was fermented1 so that any polysaccharide formed at an earlier stage would have been hydrolysed and fermented1 whereas in the presence of zinc chloride excess of sugar was present throughout the whole experiment4 ,lvoff #aiac1 #a1 #b1 #c has made quantitative experiments on the effect of methylene blue both on the sugar fermentation and autofermentation of dried yeast and maceration extract4 ,in presence of sugar the methylene blue causes a decrease in the extent of fermentation1 the difference during the time required for reduction of the methylene blue being represented by an amount of glucose equimolecular to the latter4 ,in the absence of sugar on the other hand an excess of carbon dioxide equimolecular to the methylene blue is evolved but no corresponding increase in the alcohol production occurs4 ,the effect of methylene blue is evidently complex and it is impossible at present to say whether ,lvoff's contention is correct that the methylene blue actually p#aac interferes with the fermentation by taking up hydrogen 7#b atoms per molecule of glucose7 destined for the subsequent reduction of some intermediate product or whether the effect is one of general depression of the fermenting power which would be presumably proportional to the concentration of methylene blue and inversely proportional to that of the fermenting complex see ,harden and ,norris1 ,r4 ,v41 #aiad4 ,in any case it will be noticed that ,lvoff s interpretation of the results is at variance with the requirements of ,kostytscheff's theory 7p4 #aji7 according to which #d atoms of hydrogen should be given off by a molecule of glucose4 ,kostytscheff #aiac1 #b2 ,kostytscheff and ,scheloumoff1 #aiac has also observed a depression of the extent of fermentation by methylene blue without any serious alteration in the ratio of ,,co#b to alcohol1 although an increase occurs in the production of acetaldehyde4 ,on the whole it cannot be said that the evidence gathered from experiments on the reduction of acetaldehyde and methylene blue is very convincing4 ,all that is established beyond doubt seems to be that yeast possesses a reducing mechanism for many aldehydes see also in this connection ,lintner and ,luers1 #aiac2 ,lintner and von ,liebig1 #aiaa2 as well as ,neuberg and ,steenbock1 #aiac1 #aiad and colouring matters4 ,this mechanism appears to be capable of activity in the absence of sugar and it is to be supposed that in accordance with the views of ,bach #aiac the necessary hydrogen is derived from water and that some acceptor for the oxygen simultaneously liberated is also present4 ,there seems however at the moment to be no sufficient reason to suppose that this mode of reduction is in any way altered by the presence of sugar and until the production of intermediate products equivalent to the amount of substance reduced is actually demonstrated1 the conclusions of these workers may be regarded as not fully justified4 ,neuberg and ,kerb #aiac1 #b themselves tentatively propose a complicated scheme possessing some novel features according to which methylglyoxal is the starting-point for the later stages of the change4 7_/a_/7 ,a small portion of this is converted by a reaction which may be variously interpreted as a ,cannizzaro transformation or a reductase reaction into glycerol and pyruvic acid4 ,,ch#b3;,c7,,oh7,,cho ,h#b,o ,h#b ,,ch#b7,,oh7,,ch7,,oh7,,ch#b7,,oh7 glycerol ,,ch#b3;,c7,,oh7,,cho ,o ,,ch#b3;,c7,,oh7,,cooh ,pyruvic acid 7_/b_/7 ,the pyruvic acid is then decomposed by carboxylase yielding aldehyde and carbon dioxide 7equation #b1 p4 #aji74 p#aad 7_/c_/7 ,the aldehyde and a molecule of glyoxal then undergo a ,cannizzaro reaction and yield alcohol and pyruvic acid1 ,,ch#c;,,co,,cho ,o ,,ch#c;,,co,,cooh ,,ch#c;,,cho ,h#b ,,ch#c;,,ch#b7,,oh7 and the latter then undergoes reaction 7_/b_/74 ,a small amount of glycerol is thus necessarily formed1 as is actually found to be the case4 ,the experimental foundation for stages 7_/a_/7 and 7_/c_/7 will be awaited with great interest1 as well as the proof that methylglyoxal is readily fermentable 7see p4 #ajd74 ,,the ,,formic ,,acid ,,theory4 ,an interesting interpretation of the phenomena of fermentation was attempted by ,schade #aijf based upon the conception that glucose under the influence of catalytic agents readily decomposes into acetaldehyde and formic acid4 ,it was subsequently found that the experimental evidence upon which this conclusion was founded had been wrongly interpreted ,buchner1 ,meisenheimer1 and ,schade1 #aijf2 ,schade1 #aijg1 but ,schade has succeeded in devising an interesting series of reactions by means of which alcohol and carbon dioxide can be obtained from sugar by the successive action of various catalysts4 ,the following are the stages of this series3 7#a7 ,glucose1 fructose1 and mannose are converted by alkalis into lactic acid along with other products4 7#b7 ,lactic acid when heated with dilute sulphuric acid yields a mixture of acetaldehyde and formic acid3-- ,,ch#c;,,ch7,,oh7,,cooh ,,ch#c;,,cho ,h,,cooh4 7#c7 ,it has long been known that formic acid is catalysed by metallic rhodium at the ordinary temperature into hydrogen and carbon dioxide1 and ,schade has found that when a mixture of acetaldehyde and formic acid is submitted to the action of rhodium the acetaldehyde is reduced to alcohol at the expense of the hydrogen and the carbon dioxide is evolved3-- ,,ch#c;,,cho ,h,,cooh ,,ch#c;,,ch#b7,,oh7 ,,co#b4 ,schade suggests #aijh that the fermentation of sugar may proceed by a similar series of reactions catalysed by enzymes1 the acetaldehyde and formic acid being derived not from the relatively stable lactic acid but more probably from a labile substance capable of undergoing change either into lactic acid or into aldehyde and formic acid4 ,it will be noticed that this theory resembles the pyruvic acid p#aae theory in postulating the immediate formation of acetaldehyde but differs from it by supposing that the reduction is effected at the expense of formic acid produced at the same time4 ,the acetaldehyde question has already been discussed4 ,in view of the fact that formic acid is a regular product of the action of many bacteria on glucose see ,harden1 #aija1 ,schade's theory of alcoholic fermentation may be said to be a possible interpretation of the facts4 ,formic acid is known to be present in small amounts in fermented sugar solutions and the actual behaviour of yeast towards this substance has been investigated in some detail by ,franzen and ,steppuhn #aiaa2 #aiab1 #a1 #b1 who have obtained results strongly reminiscent of those obtained with lactic acid by ,buchner and ,meisenheimer 7p4 #ajb74 ,many yeasts when grown in presence of sodium formate decompose a certain proportion of it1 whereas in absence of formate they actually produce a small amount of formic acid--the absolute quantities being usually of the order of #jjjje gram molecule 7#jjbc gram7 per #ajj c4c4 of medium in #d to #e days4 ,only in the case of _/,s4 validus_/ did the consumption of formic acid in #e days reach #jjjag gram molecule 7#jjh gram74 ,somewhat similar but rather smaller results were given by yeast-juice1 a small consumption of formic acid being usually observed4 ,the possibility thus exists that formic acid may be an intermediate product of alcoholic fermentation and ,franzen argues strongly in favour of this view4 ,direct experiment1 on the other hand1 shows that yeast-juice cannot ferment a mixture of acetaldehyde and formic acid1 even when these are gradually produced in molecular proportions in the liquid by the slow hydrolysis of a compound of the two1 ethylideneoxyformate1 ,,ohc,o,,ch7,,ch#c7,o,,ch7,,ch#c7,o,,cho 1 this method being adopted to avoid the inhibiting effect of free acetaldehyde and formic acid ,buchner and ,meisenheimer1 #aiaj4 ,nor is the reduction of acetaldehyde assisted by the presence of formate ,neuberg and ,kerb1 #aiab1 #d2 ,kostytscheff and ,hbbenet1 #aiab4 ,a modified form of ,schade's theory has been suggested by ,ashdown and ,hewitt #aiaj1 who have found that when brewer's yeast is cultivated in presence of sodium formate the yield of aldehyde1 as a rule1 becomes less4 ,they regard the aldehyde as derived from alanine1 ,,ch#c;,,ch7,,nh#b7;,,cooh1 one of the amino-acids formed from the proteins by hydrolysis1 which is known to be attacked by yeast in the characteristic manner 7p4 #hg71 forming alcohol1 carbon dioxide1 and ammonia4 ,fermentation is supposed to proceed in such a way that the sugar is first decomposed into two smaller molecules1 ,c#c;,h#f,o#c p#aaf 7equation i71 and that these react with formamide to produce alanine and formic acid 7ii74 ,the alanine then enters into reaction with formic acid1 producing alcohol1 carbon dioxide1 and formamide 7iii73-- 7i7 ,c#f;,h#ab,o#f #b;,c#c;,h#f,o#c4 7ii7 ,c#c;,h#f,o#c ,h,,co,,nh#b ,,ch#c;,,ch7,,nh#b7;,,cooh ,h,,cooh4 7iii7 ,,ch#c;,,ch7,,nh#b7;,,cooh ,h,,cooh ,,ch#c;,,ch#b,,oh ,,co#b ,h,,co,,nh#b4 ,according to this scheme all the sugar fermented passes through the form of alanine1 and the formic acid acts along with the enzyme as catalyst1 passing into formamide in reaction 7iii7 and being regenerated in 7ii74 ,the alanine is in the first place derived from the hydrolysis of proteins1 or possibly by the reaction of the ,c#c;,h#f,o#c group with one of the higher amino-acids3-- ,c#c;,h#f,o#c ,cn,h#bn#a;,,ch7,,nh#b7;,,cooh ,cn,h#bn#a;,,ch#b,,oh ,,co#b ,,ch7,,nh#b7;,,cooh4 ,there is as little positive evidence for this course of events as for that postulated by ,schade1 and the theory suffers from the additional disability that the chemical reactions involved have not been realised in the laboratory4 ,direct experiments with yeast-juice1 moreover1 show that a mixture of alanine with formic acid or a formate is not fermented1 whilst neither the added mixture nor formamide seriously effects the action of the juice on glucose4 ,,other ,,theories4 ,among other suggestions may be mentioned that of ,kohl #aiji who asserts that sodium lactate is readily fermented1 whilst ,kusseroff #aiaj holds the view that the glucose is first reduced to sorbitol and the latter fermented1 in spite of the fact that sorbitol itself in the free state is not fermented by yeast4 ,the rapid appearance and disappearance of glycogen in the yeast cell at various stages of fermentation see ,pavy and ,bywaters1 #aijg2 ,wager and ,peniston1 #aiaj has led to the suggestion ,grss1 #aijd2 ,kohl1 #aijg that this substance is of great importance in fermentation1 and represents a stage through which all the sugar must pass before being fermented4 ,the fact that the formation of glycogen has been observed in yeast-juice by ,cremer #ahii1 and that complex carbohydrates are also undoubtedly formed 7p4 #ca71 are consistent with this theory4 ,the low rate of autofermentation of living yeast1 which is only a few per cent4 of the rate of sugar fermentation1 renders this supposition very improbable 7,slator71 as does the fact that the fermentation of glycogen by yeast-juice is usually slower than that of glucose see also ,euler1 #aiad4 ,an entirely different explanation of the chemical changes attendant on alcoholic fermentation has been suggested by p#aag ,lb #aijf2 #aijh1 #a1 #b2 #aiji1 #a1 #b1 #c1 #d2 #aiaj2 ,lb and ,pulvermacher1 #aiji1 founded on the idea that the various decompositions of the sugar molecule both by chemical and biological agents are to be explained by a reversal of the synthesis of sugar from formaldehyde4 ,as the sugar molecule can be built up by the condensation of formaldehyde1 so it tends to break down again into this substance1 and the products observed in any particular case are formed either by partial depolymerisation in this sense or by partial re-synthesis following on depolymerisation4 ,lb has adduced many striking facts in favour of this view1 and has shown that very dilute alkalis produce no lactic acid but formaldehyde and a pentose as primary products4 ,these substances represent the first stage of depolymerisation and are also formed by the electrolysis of glucose4 ,lb has himself been unable to detect definite intermediate products of fermentation by adding reagents1 such as aniline1 ammonia1 and phloroglucinol1 which would combine with such substances and prevent their further decomposition #aijf4 ,the occurrence of traces of formaldehyde as a product of alcoholic fermentation by yeast-juice ,lebedeff1 #aijh is at least consistent with this theory1 but no decisive evidence has so far been obtained either for or against it4 ,in all the foregoing attempts to indicate the probable stages in the production of alcohol and carbon dioxide from sugar1 a single molecule of the sugar forms the starting-point4 ,the facts recounted in ,chapter ,,iii as to the function of phosphates in alcoholic fermentation1 which are summed up in the equation3-- #b;,c#f;,h#ab,o#f #b,r#b;,,hpo#d #b;,,co#b #b;,c#b;,h#f,o #b;,h#b,o ,c#f;,h#aj,o#d7,,po#d,r#b7b1 render it in the highest degree probable that two molecules of the sugar are concerned4 ,the most reasonable interpretation of this equation appears to be that in the presence of phosphate and of the complicated machinery of enzyme and co-enzyme two molecules of the hexose1 or possibly of the enolic form1 are each decomposed primarily into two groups4 ,of the four groups thus produced1 two go to form alcohol and carbon dioxide and the other two are synthesised to a new chain of six carbon atoms1 which forms the carbohydrate residue of the hexosephosphate4 ,the introduction of the phosphoric acid groups may possibly occur before the rupture of the original molecules1 and may even be the determining factor of this rupture1 or again this introduction may take place during or after the formation of the new carbon p#aah chain4 ,sufficient information is not yet available for the exact formulation of a scheme for this reaction4 ,such a scheme1 it may be noted1 would not necessarily be inconsistent with the views of ,wohl and of ,buchner as to the way in which the carbon chain of a hexose is broken in the process of fermentation1 but would interpret differently the subsequent changes which are undergone by the simpler groups which are the result of this rupture4 ,the reaction might thus proceed without the formation of definite intermediate products1 whilst opportunity would be afforded for the production of a small quantity of by-products such as formaldehyde1 glycerol1 lactic acid1 acetic acid1 etc41 by secondary reactions4 ,a symmetrical scheme can readily be constructed for such a change1 but much further information is required before any decisive conclusion can be drawn as to the precise course of the reaction which actually occurs in alcoholic fermentation4 p#aai ,,chapter ,,ix4 ,,the ,,mechanism ,,of ,,fermentation4 ,the analysis of the process of alcoholic fermentation by yeast-juice and other preparations from yeast which has been carried out in the preceding chapters has shown that the phenomenon is one of a very complex character4 ,the principal substances directly concerned in the change appear to be the enzyme and co-enzyme of the juice1 a second enzyme1 hexosephosphatase1 and1 in addition1 sugar1 phosphate1 and the hexosephosphate formed from these4 ,during autofermentation two other factors are involved1 the complex carbohydrates of the juice1 including glycogen and dextrins1 and the diastatic ferment by which these are converted into fermentable sugars4 ,it is also possible that the supply of free phosphate is partially provided by the action of proteoclastic ferments on phosphoproteins4 ,under special circumstances the rate at which fermentation proceeds may be controlled by the available amount of any one of these numerous substances4 ,when the juice from well-washed yeast is incubated1 the phenomenon of autofermentation is observed4 ,the juice contains an abundant supply of enzyme1 co-enzyme1 and phosphate or hexosephosphate1 and in this case the controlling factor is usually the supply of sugar1 which is conditioned by the concentration of the diastatic enzyme or of the complex carbohydrates as the case may be4 ,when this is the case the measured rate of fermentation is the rate at which sugar is being produced in the juice1 this being the slowest of the various reactions which are proceeding under these circumstances4 ,if sugar be now added1 an entirely different state of affairs is set up4 ,as soon as any accumulated phosphate has been converted into hexosephosphate1 the normal rate of fermentation which is usually higher than that of autofermentation is attained1 and1 provided that excess of sugar be present1 fermentation continues for a considerable period at a slowly diminishing rate and finally ceases4 ,during the first part of this fermentation the rate is controlled entirely by the supply of free phosphate1 and this depends mainly on the concentration of the hexosephosphatase and of the hexosephosphate1 and only in a secondary degree on the decomposition p#abj of other phosphorus compounds by other enzymes and on the concentration of the sugar4 ,the amount of hexosephosphate in yeast-juice is usually such that an increase in its concentration does not greatly affect the rate of fermentation1 and hence the measured rate during this period represents the rate at which hexosephosphate is being decomposed1 and this in its turn depends on the concentration of hexosephosphatase1 which is therefore the controlling factor4 ,as fermentation proceeds1 the concentration of both enzyme and co-enzyme steadily diminishes1 as already explained1 probably owing to the action of other enzymes1 so that at an advanced stage of the fermentation1 the controlling factor may be the concentration of either of these1 or the product of the two concentrations 7see p4 #abb74 ,the hexosephosphatase appears invariably to outlast the enzyme and co-enzyme4 ,the condition at any moment could be determined experimentally if it were possible to add enzyme1 co-enzyme and hexosephosphatase at will and so ascertain which of these produced an acceleration of the rate4 ,unfortunately this can at present be only very imperfectly accomplished1 owing to the impossibility of separating these substances from each other and from accompanying matter which interferes with the interpretation of the result4 ,a third condition can also be established by adding to the fermenting mixture of the juice and sugar a solution of phosphate4 ,the supply of phosphate is now almost independent of the action of the hexosephosphatase1 and the measured rate represents the rate at which reaction 7#a71 p4 #ea1 can occur between sugar and phosphate in the presence of the fermenting complex consisting of enzyme and co-enzyme4 ,this change is controlled1 so long as sugar and phosphate are present in the proper amounts1 by the concentration of the fermenting complex or possibly of either the enzyme or the co-enzyme4 ,if only a single addition of a small quantity of phosphate be made1 the rate falls as soon as the whole of this has been converted into hexosephosphate and the reaction then passes into the stage just considered1 in which the rate is controlled by the production of free phosphate4 ,although these varying reactions have not yet been exhaustively studied from the kinetic point of view1 owing to the experimental difficulties to which allusion has already been made1 investigations have nevertheless been carried out on the effect of the variation of concentration of yeast-juice and zymin as a whole1 as well as of the carbohydrate4 ,herzog #aijb1 #aijd has made experiments of this kind with zymin1 and ,euler #aije with yeast-juice1 whilst many of the results p#aba obtained by ,buchner and by ,harden and ,young are also available4 ,the actual observations made by these authors show that the initial velocity of fermentation is almost independent of the concentration of sugar within certain limits1 but decreases slowly as the concentration increases4 ,when the velocity constant is calculated on the assumption that the reaction is monomolecular see ,bayliss1 #aiad1 ,chap4 ,,vi1 approximate constancy is found for the first period of the fermentation4 ,this method of dealing with the results is1 however1 as pointed out by ,slator1 misleading1 the apparent agreement with the law of monomolecular reactions being probably due to the gradual destruction of the fermenting complex4 ,experiments with low concentrations of sugar are difficult to interpret1 the influence of the hydrolysis of glycogen and of dextrins on the one hand1 and the synthesis of sugar to more complex carbohydrates on the other 7p4 #ca71 having a relatively great effect on the concentration of the sugar4 ,unpublished experiments 7,harden and ,young7 indicate1 however1 that the velocity of fermentation remains approximately constant1 until a certain very low limit of sugar concentration is reached1 and then falls rapidly4 ,the fall in rate1 however1 only continues over a small interval of concentration1 after which the velocity again becomes approximately constant and equal to the rate of autofermentation4 ,during this last phase1 as already indicated1 the velocity is generally controlled by the rate of production of sugar and no longer by that of phosphate1 this substance being now present in excess4 ,in other words1 the rate of fermentation of sugar by yeast-juice and zymin is not proportional to the concentration of the sugar present as required by the law of mass1 but1 after a certain low limit of sugar concentration1 is independent of this and is actually slightly decreased by increase in the concentration of the sugar4 ,the relations here are very similar to those shown to exist by ,duclaux #ahii and ,adrian ,brown #aijb for the action of invertase on cane sugar and are probably to be explained in the manner suggested by the latter4 ,according to this investigator1 the enzyme unites with the fermentable material1 or as it is now termed1 the substrate or zymolyte1 forming a compound which only slowly decomposes so that it remains in existence for a perceptible interval of time4 ,the rate of fermentation depends on the rate of decomposition of this compound and hence varies with its concentration4 ,this conception leads to the result that the rate of fermentation will increase with the concentration of the substrate up to a certain limit and will then remain p#abb constant1 unless interfered with by secondary actions4 ,this limit of concentration is that at which there is just sufficient of the material in question present to combine with practically the whole of the enzyme1 so that no further increase in its amount can cause a corresponding increase in the quantity of its compound with the enzyme or in the rate of fermentation which depends on the concentration of that compound4 ,the curve relating the rate of action of such an enzyme with the concentration of the zymolyte therefore consists of two portions1 one in which the rate at any moment is proportional to the concentration of the zymolyte1 according to the well-known law of the action of mass1 and a second in which the rate at any moment is almost independent of that concentration1 approximately equal amounts being decomposed in equal times whatever the concentration of the substrate4 ,the results of the experiments with yeast-juice therefore indicate that what is being measured is a typical enzyme action1 but afford no information as to which of the many possible actions is the controlling one1 a fact which must be ascertained for each particular case in the manner indicated above4 ,clowes #aiji1 using washed zymin free from fermenting power and adding various volumes of boiled yeast extract1 found that the velocity of reaction was proportional to the product of the concentrations of zymin and yeast extract up to a certain optimum concentration4 ,he interprets these concentrations as representing the concentrations of zymase and co-enzyme1 but they also represent the concentrations of hexosephosphatase 7present in the zymin7 and phosphate 7present in the yeast extract71 so that at least four factors were being altered instead of only two4 ,it has already been mentioned that ,euler and ,kullberg #aiaa1 #c found the conversion of phosphate into hexosephosphate in presence of excess of glucose to proceed according to a monomolecular reaction 7p4 #eh74 ,the rate of fermentation is diminished by dilution of the yeast-juice1 but less rapidly than the concentration of the juice4 ,herzog found that when the relation between concentration of enzyme and the velocity constant of the reaction is expressed by the formula ,k#a_/,k#b 7,c#a_/;,c#b7_/n_/ where ,k#a and ,k#b are the velocity constants corresponding with the enzyme concentrations ,c#a and ,c#b1 the value for _/n_/ is #b for zymin1 whilst ,euler working with yeast-juice obtained values varying from #abi to #afg and decreasing as ,k increased4 ,the temperature coefficient of fermentation by zymin was found p#abc by ,herzog to be ,k#bde_/,k#ade #bhh1 which agrees well with the value found by ,slator for yeast-cells 7p4 #abi74 ,when we endeavour to apply the results of the investigations of the fermentation of sugar by yeast-juice1 zymin1 etc41 to the process which goes on in the living cell1 considerable difficulties present themselves4 ,a scheme of fermentation in the living cell can1 however1 easily be imagined1 which is in harmony with these results4 ,according to the most simple form of this ideal scheme1 the sugar which has diffused into the cell unites with the fermenting complex and undergoes the characteristic reaction with phosphate1 already present in the cell1 yielding carbon dioxide1 alcohol1 and hexosephosphate4 ,the latter is then decomposed1 just as it is in yeast-juice1 but more rapidly1 and the liberated phosphate again enters into reaction1 partly with the sugar formed from the hexosephosphate and partly with fresh sugar supplied from outside the cell4 ,the main difference between fermentation by yeast-juice and by the living cell would then consist in the rate of decomposition of the hexosephosphate1 for it has been shown that yeast-juice in presence of sufficient phosphate can ferment sugar at a rate of the same order of magnitude 7from #cj to #ej per cent47 as that attained by living yeast4 ,the difference between the two therefore would appear to lie not so much in their content of fermenting complex as in their very different capacity for liberating phosphate from hexosephosphate and thus supplying the necessary conditions for fermentation4 ,a simple calculation based on the phosphorus content of living yeast ,buchner and ,haehn1 #aiaj1 #b shows that the whole of this phosphate must pass through the stage of hexosephosphate every five or six minutes in order to maintain the normal rate of fermentation1 whereas in an average sample of yeast-juice the cycle1 calculated in the same way1 would last nearly two hours4 ,wherein this difference resides is a difficult question1 which cannot at present be answered with certainty4 ,in the first place it must be remembered that a very great acceleration of the action of the hexosephosphatase is produced by arsenates 7p4 #gi71 and this suggests the possibility that some substance possessing a similar accelerating power is present in the yeast-cell and is lost or destroyed in the various processes involved in rendering the yeast susceptible to phosphate4 ,the great variety of these processes--extraction of yeast-juice by grinding and pressing1 drying and macerating1 heating1 treating with acetone and with toluene--renders this somewhat improbable1 and so far no such substance has been detected4 p#abd ,a comparison of living yeast1 zymin1 and yeast-juice shows that these are situated on an ascending scale with respect to their response to phosphate4 ,taking fructose as the substrate in each case1 yeast does not respond to phosphate at all 7,slator71 the rate of fermentation by zymin is approximately doubled 7p4 #df71 and that by yeast-juice increased ten to forty times1 whilst the maximum rates are in each case of the same order of magnitude4 ,euler and ,kullberg1 however1 have observed an acceleration of about #be per cent4 in the rate of fermentation of yeast in presence of a #b per cent4 solution of monosodium phosphate1 ,na,h#b,,po#d #aiaa1 #a1 #b4 ,the high rate of fermentation by living yeast and its lack of response to phosphate may possibly be explained by supposing that the balance of enzymes in the living cell is such that the supply of phosphate is maintained at the optimum1 and the rate of fermentation cannot therefore be increased by a further supply4 ,a further difference lies in the fact that yeast-juice and zymin respond to phosphate more strongly in presence of fructose than of glucose1 whereas yeast ferments both sugars at the same rate 7p4 #aca71 and this property has been shown to be connected with the specific relations of fructose to the fermenting complex4 ,it seems possible that these differences are associated with the gradual passage from the complete living cell of yeast1 through the dead and partially disorganised cell of zymin to yeast-juice in which the last trace of cellular organisation has disappeared and the contents of the cell are uniformly diffused throughout the liquid4 ,living yeast is1 moreover1 not only unaffected by phosphate but only decomposes hexosephosphate extremely slowly 7,iwanoff74 ,some light is thrown on these interesting problems by the effect of antiseptics on fermentation by yeast-cells and by yeast-juice4 ,the action of toluene has hitherto been most completely studied1 and this substance is an extremely suitable one for the purpose since it has practically no action whatever on fermentation by yeast-juice4 ,the experiments of ,buchner have1 in fact1 shown that the normal rate of fermentation and the total fermentation produced1 are almost unaffected by the presence of toluene even in the proportion of #a c4c4 to #bj c4c4 of yeast-juice4 ,what then is the effect of toluene on the living yeast-cell8 ,when toluene in large excess is agitated with a fermenting mixture of yeast and sugar1 the rate of fermentation falls rapidly at first and then more slowly until a relatively constant rate is attained which gradually decreases in a similar manner to the rate of fermentation by yeast-juice4 ,thus at air temperature 7#af7 #aj grams of p#abe yeast suspended in #ej c4c4 of #f per cent4 glucose solution gave the following results when agitated with toluene3-- ,time after ,addition ,c4c4 of ,,co#b ,time4 ,c4c4 per of ,toluene1 ,minutes per ,minute4 ,minute #j #df #f #af #a #d #h #ab #b #cc #ab #jhe #c #bf #bd #jh #d #b #cb #je #e #ah constant ,simultaneously with this1 the yeast acquires the property of decomposing and fermenting hexosephosphate and of responding to the addition of phosphate4 ,this last property is only acquired to a small degree in this way but it becomes much more strongly developed if the pressed yeast be washed with toluene on the filter pump4 ,thus #aj grams of yeast after this treatment fermented fructose at #ab c4c4 per three minutes2 after the addition of phosphate 7#e c4c4 of #jf molar phosphate7 the rate rose to #fi and then gradually fell in the typical manner ,harden1 #aiaj2 see also ,euler and ,johansson1 #aiab1 #c4 ,the current explanation of the great decrease in rate of fermentation which attends the action of toluene and other antiseptics on living yeast1 and also follows upon the disintegration of the cell1 appears to be that in living yeast the high rate of fermentation is maintained by the continued production of relatively large fresh supplies of fermenting complex1 and that when the power of producing this catalytic agent is destroyed by the poison1 the rate of fermentation falls to a low value1 corresponding to the store of zymase still present in the cell 7cf4 ,buchner1 ,e4 and ,h41 and ,hahn1 #aijc1 pp4 #agf1 #ahj74 ,this explanation implies that the rate of fermentation after the action of the toluene represents the amount of fermenting complex present1 a supposition which has been shown 7p4 #ec7 to be highly improbable4 ,it further necessitates1 as also pointed out independently by ,euler and ,ugglas #aiaa1 a rapid destruction of the fermenting complex both in the process of fermentation and by the action of the antiseptic1 as otherwise the store of zymase remaining in the dead cell would be practically the same as that contained in the living cell at the moment when it was subjected to the antiseptic1 and this store would therefore suffice to carry out fermentation at the same rate in the dead as in the living cell4 ,no such rapid destruction1 however1 occurs in yeast-juice1 as judged by the rate of fermentation1 which falls off p#abf slowly and to about the same extent in the presence or absence of toluene4 ,moreover1 as shown above1 it is highly probable that the actual amount of fermenting complex in yeast-juice is a large fraction of that present at any moment in the cell1 and is capable under suitable conditions of producing fermentation at a rate comparable with that of the living cell4 ,this last criticism also applies to the view expressed by ,euler ,euler and ,ugglas1 #aiaa2 ,euler and ,kullberg1 #aiaa1 #a1 #b that in the living cell the zymase is partly free and partly combined with the protoplasm2 when the vital activity of the cell is interfered with1 the combined portion of the zymase is thrown out of action and only that which was free remains active4 ,the suggestion made by ,rubner #aiac that the action of yeast on sugar is in reality chiefly a vital act1 but that a small proportion of the change is due to enzyme action1 is similar in its consequences to that of ,euler and may be met by the same arguments4 ,buchner and ,skraup #aiad have moreover shown that the effects of sodium chloride and toluene on the fermenting power of yeast which were observed by ,rubner1 can be explained in other ways4 ,some other explanation must therefore be sought for this phenomenon4 ,great significance must be attached in this connection to the relation noted above between the degree of disintegration and disorganisation of the cell and the fall in the normal rate of fermentation4 ,it seems not impossible that fermentation may be associated in the living cell with some special structure1 or carried on in some special portion of the cell1 perhaps the nuclear vacuole described by ,janssens and ,leblanc #ahih1 ,wager #ahih1 #aiaa2 ,wager and ,peniston1 #aiaj and others which undergoes remarkable changes both during fermentation and autofermentation ,harden and ,rowland1 #aija4 ,the disorganisation of the cell might lead to many modifications of the conditions1 among others to the dilution of the various catalytic agents by diffusion throughout the whole volume of the cell4 ,as a matter of observation the dilution of yeast-juice leads to a considerable diminution of the rate of fermentation of sugar1 and it is possible that this is one of the chief factors concerned4 ,that phenomena of this kind may be involved is shown by the remarkable effect of toluene on the autofermentation of yeast4 ,whereas the fermentation of sugar is greatly diminished by the action of toluene1 the rate of autofermentation1 which is carried on at the expense of the glycogen of the cell1 is greatly increased4 ,in a typical case1 for example1 the autofermentation of #aj grams of yeast suspended in #bj c4c4 of water amounted to #bh c4c4 in #dh hours p#abg at #be1 whereas the same amount of yeast in presence of #b c4c4 of toluene gave #igf c4c4 in the same time4 ,many salts produce a similar effect on ,english top yeasts 7in which the autofermentation is large7 ,harden and ,paine1 #aiab1 whereas ,neuberg and ,karczag in ,berlin #aiaa1 #b were unable to observe this phenomenon4 ,a necessary preliminary of the fermentation of glycogen is its conversion by a diastatic enzyme into a fermentable sugar1 and it is probable that the effect of the disorganisation of the cell by toluene is that this enzyme finds more ready access to the glycogen1 which is stored in the plasma of the cell4 ,no such acceleration of autofermentation is effected by the addition of toluene to yeast-juice1 and hence the result is not due to an acceleration of the action of the diastatic enzyme on the glycogen4 ,this effect of toluene is similar in character to the action of ansthetics on the leaves of many plants containing glucosides and enzymes1 whereby an immediate decomposition of the glucoside is initiated see ,h4 ,e4 and ,e4 ,f4 ,armstrong1 #aiaj4 ,although as indicated above ,euler's theory cannot apply to zymase itself1 if applied to the hexosephosphatase it would afford a consistent explanation of the facts4 ,according to this modified view it would be the hexosephosphatase of yeast which existed largely in the combined form1 so that in extracts1 in dried yeast and in presence of toluene only the small fraction which was free would remain active4 ,the zymase on the other hand would have to be regarded as existing to a large extent in the free state so that it would pass into extracts comparatively unimpaired in amount and capable under proper conditions 7i4e4 when supplied with sufficient phosphate7 of bringing about a very vigorous fermentation4 ,the theory of combined and free enzymes is undoubtedly of considerable value1 although it cannot be considered as fully established4 ,,fermentation ,,by ,,living ,,yeast4 ,much important information as to the nature of the processes involved in fermentation has been acquired by the direct experimental study of the action of living yeast on different sugars4 ,this phenomenon has formed the subject of several investigations from the kinetic point of view1 and its general features may now be regarded as well established4 ,the difficulty1 which must as far as possible be avoided in quantitative experiments of this sort with living yeast1 is the alteration p#abh in the amount or properties of the yeast1 due to growth or to some change in the cells4 ,this has been obviated in the work of ,slator #aijf by determining in every case the initial rate of fermentation1 so that the process only continues for a very short period1 during which any change in the amount or constitution of the yeast is negligible4 ,the method has the further advantage that interference of the products of the reaction is to a large extent avoided4 ,the pressure apparatus already described 7p4 #bi7 was employed by ,slator1 the rate of production of carbon dioxide being measured by the increase of pressure in the experimental vessel4 ,,influence ,,of ,,concentration ,,of ,,dextrose ,,on ,,the ,,rate ,,of ,,fermentation4 ,with regard to this important factor it is found that the action of living yeast follows the same law as that of most enzymes 7p4 #aba72 within certain wide limits the rate of fermentation is almost independent of the concentration of the sugar4 ,this conclusion has been drawn by many previous investigators from their experiments ,dumas1 #ahgd2 ,tammann1 #ahhi2 ,adrian ,brown1 #ahib2 ,o',sullivan1 #ahih1 #ahii and is implicitly contained in the results of ,aberson #aijc1 although he himself regarded the reaction as monomolecular4 ,illustration3 ,,fig4 #h4 7,graph ,fermentation ,velocity vs ,conc4 ,dextrose--,ed47 ,slator1 working with a suspension of ten to twelve yeast-cells per #a_/djjj cubic millimetre at #cj1 obtained the results which are embodied in the curve 7,fig4 #h74 ,this shows that1 for the amount of yeast in question1 the rate of fermentation is almost constant for concentrations of glucose between p#abi #a and #aj grams per #ajj c4c41 but gradually decreases as the concentration increases4 ,below #a gram per #ajj c4c4 the rate decreases very rapidly with the concentration4 ,it follows from this1 in the light of what has already been said 7p4 #aba71 that the action of living yeast on sugar follows the same course as a typical enzyme reaction1 although in this case1 as in that of yeast-juice1 no information is given as to the exact nature of this reaction4 ,,influence ,,of ,,the ,,concentration ,,of ,,yeast4 ,it appears to be well established that1 when changes in the quantity and constitution of the yeast employed are eliminated1 the rate of fermentation is exactly proportional to the number of the yeast-cells present 7,aberson1 ,slator74 ,this result might be anticipated1 as pointed out by ,slator1 from the fact that the fermentation takes place within the cell1 each cell acting as an independent individual4 ,the diffusion of sugar into the yeast-cell which necessarily precedes the act of fermentation has been shown by ,slator and ,sand #aiaj to occur at such a rate that the supply of sugar is always in excess of the amount which can be fermented by the cell4 ,,temperature ,,coefficient ,,of ,,alcoholic ,,fermentation ,,by ,,yeast4 ,the temperature coefficient of fermentation by living yeast has been carefully determined by ,slator by measurements of the initial rates at a series of temperatures from #e to #dj ,c4 ,the coefficient is found to be of the same order as that for many chemical reactions1 but to vary considerably with the temperature1 a rise in temperature corresponding with a diminution in the coefficient4 ,the following values were obtained for glucose2 they are independent of the concentration of yeast and glucose1 the class of yeast1 and presence or absence of nutrient salts1 and remain the same when inhibiting agents are present4 ,almost precisely the same ratios are obtained for fructose and mannose3-- t4 ,v_/t_/ #e_/,v_/t4_/ ,v_/t_/ #aj_/,v_/t4_/ #e #bfe #ef #aj #baa #ch #ae #ahj #bh #bj #aeg #bbe #be #adc #aie #cj #ace #af #ce #abj ,aberson's result1 ,k_/t_/ #aj_/,k_/t_/ #bgb1 which represents the mean coefficient for #aj between #ab and #cc1 agrees well with this4 p#acj ,,action ,,of ,,accelerating ,,agents ,,on ,,living ,,yeast4 ,slator #aijh1 #a was unable to find any agent which greatly accelerated the rate of fermentation of living yeast4 ,small concentrations of various inhibiting agents which are often supposed to act in this way were quite ineffective1 and phosphates1 which produce such a striking change in yeast-juice1 were almost without action 7cp4 p4 #abd74 ,euler and ,bckstrm #aiab1 however1 have made the important observation that sodium hexosephosphate causes a considerable acceleration although it is itself neither fermented nor hydrolysed under these conditions4 ,the extent of this is evident from the following numbers3-- #bj c4c4 of #bj per cent4 glucose solution4 #jbe g4 yeast ,yeast ,h of ,st4 ,erik's brewery4 ,without addition4 #je g4 ,na hexosephosphate4 ,time4 ,,co#b4 ,time4 ,,co#b4 ,min4 ,min4 #df #aje #cg #h #gf #age #gc #ai #aig #de #ahh #ebe #cdg #gde #cba #abc #dhh #ie #dej #aice ,the observation has been confirmed with ,english top yeast 7,harden and ,young1 unpublished experiments71 but no explanation of the phenomenon is at present forthcoming4 ,euler has also found ,euler and ,cassel1 #aiac2 ,euler and ,berggren1 #aiab that yeast extract1 sodium nucleinate and ammonium formate also increase the rate of fermentation of glucose by yeast1 but these results have been criticised by ,harden and ,young #aiac on the ground that the possibility of growth of the yeast during the experiment has not been excluded4 ,,fermentation ,,of ,,different ,,sugars ,,by ,,yeast4 ,many valuable ideas as to the nature of fermentation have been obtained by a consideration of the phenomena presented by the action of yeast on the different hexoses4 ,of these only glucose1 fructose1 mannose1 and galactose are susceptible of alcoholic fermentation by yeast1 the stereoisomeric hexoses prepared in the laboratory being unfermentable1 as are also the pentoses1 tetroses1 and the alcohols corresponding to all the sugars4 ,the yeast-cell is therefore much more limited in its power of producing fermentation than such an organism as1 for example1 _/,bacillus coli communis_/1 which attacks substances as p#aca diverse as arabinose1 glucose1 glycerol and mannitol1 and yields with all of them products of the same chemical character1 although in varying proportions4 ,a careful examination of a number of different genera and species of the ,saccharomycetace and allied organisms by ,e4 ,f4 ,armstrong #aije has shown that all yeasts which ferment glucose also ferment fructose and mannose4 ,armstrong grew his yeasts in a nutrient solution containing the sugar to be investigated1 and his experiments are open to the criticism that the organisms were hereby afforded an opportunity for becoming acclimatised to the sugar4 ,his results1 therefore1 only demonstrate the fact that the organisms in question when cultivated in presence of the sugars examined brought about their fermentation1 and do not exclude the possibility that the same organism when grown in presence of a different sugar might not be capable of fermenting the one to which it had in the other type of experiment become acclimatised4 ,this has actually been shown to be the case for galactose by ,slator #aijh1 #a1 and it is possible that this circumstance explains the negative results obtained by ,lindner #aije with _/,s4 exiguus_/ and _/,schizosaccharomyces ,pombe_/ upon mannose1 a sugar which1 according to ,armstrong1 is fermented by both these organisms4 ,the same problem has been attacked quantitatively by ,slator1 who has shown that living yeast of various species and genera ferments glucose and fructose at approximately the same rate4 ,moreover1 when the yeast is acted upon by various inhibiting agents1 such as heat1 iodine1 alcohol1 or alkalis1 the crippled yeast also ferments glucose and fructose at the same rate4 ,with mannose the relations are somewhat different4 ,the relative rate of fermentation of mannose and glucose by yeast is dependent on the variety of the yeast and the treatment which it has received4 ,fresh samples of yeast ferment mannose more quickly than glucose1 but by older samples the glucose is the more rapidly decomposed4 ,this is especially the case with yeast1 the activity of which has been partly destroyed by heat1 the relative fermenting power to mannose being sometimes reduced by this treatment from #abj per cent4 of that of glucose to only #ab per cent4 7,slator74 ,a further difference consists in the fact that with certain yeasts the rate of fermentation of glucose is somewhat increased by monosodium phosphate whilst that of mannose is unaffected ,euler and ,lundeqvist1 #aiaa4 ,mixtures of glucose and fructose are fermented by yeast at the p#acb same rate as either the glucose or the fructose contained in the mixture would be alone4 ,when1 however1 mannose and glucose are fermented simultaneously interference between the reactions takes place1 and this is especially evident when the yeast has comparatively little action on mannose4 ,the following are the results obtained by ,slator3-- ,relative ,rates4 ,yeast4 #be per cent4#be per cent4#be per cent4 ,glucose ,glucose4 ,mannose4 #be per cent4 ,mannose4 ,s4 ,thermantitonum #ajj #aje #ib ,brewery yeast1 #ec per cent4 activity destroyed by heat #ajj #ba #cc ,brewery yeast1 #fj per cent4 activity destroyed by heat #ajj #ab #db ,the case of galactose merits special attention4 ,previous investigations see ,lippmann1 #aijd1 p4 #gcd have shown that the fermentation of galactose by yeast differs greatly from that of the other hexoses4 ,the subject has been re-investigated by ,e4 ,f4 ,armstrong #aije1 and by ,slator #aijh1 #a4 ,armstrong carried out his experiments in the manner already described 7p4 #aca71 and found that some yeasts had1 and others had not1 the power of fermenting galactose1 although all were capable of fermenting glucose1 fructose1 and mannose4 ,slator made quantitative experiments on the same subject4 ,he was able to confirm the statement which had previously been made1 that certain yeasts which have the property of fermenting galactose possess it only after the yeast has become acclimatised by culture in presence of the sugar4 ,this was shown for brewery yeast and for the species mentioned below4 ,this phenomenon is one of great interest and is strictly analogous to the adaptation of bacteria which has now been quite conclusively established ,neisser1 #aijf4 ,relative ,rates4 ,yeast4 ,mode of ,culture4 ,grown in3 ,glucose4 ,galactose4 ,s4 ,carlsbergensis wort #ajj #a hydrolysed lactose #ajj #hf1 #hc1 #he1 #be1 #df1 #ea1 #fi1 #ed1 #aee ,s4 ,cerevisi wort #ajj #a hydrolysed lactose #ajj #ba1 #bf1 #bi ,s4 ,thermantitonum4 wort #ajj #a hydrolysed lactose #ajj #gg1 #ec1 #ce ,s4 ,ludwigii wort #ajj #a hydrolysed lactose #ajj #a p#acc ,it will be seen that in one case the rate of fermentation of galactose was considerably greater than that of glucose4 _/,s4 ,ludwigii_/ did not respond to the cultivation in hydrolysed lactose1 but1 as ,slator points out1 it is quite possible that repeated cultivation in this medium might effect the change1 and this would be strictly analogous to the results obtained with bacteria4 ,slator's results have been confirmed by ,harden and ,norris1 ,r4 ,v4 #aiaj1 and by ,euler and ,johansson #aiab1 #b who have made an exceedingly interesting study of the progress of the adaptation4 ,as in the case of mannose the rates of fermentation of glucose and galactose are differently affected by agents such as heat and alcohol2 moreover1 the rate of fermentation of mixtures of dextrose and galactose is in no case either the sum or the mean of the rates obtained with the separate sugars4 ,the temperature coefficient of the fermentation of galactose also differs slightly from that of the other hexoses4 ,relative ,rates4 ,yeast4 ,glucose4 ,galactose4 ,glucose ,galactose4 ,s4 ,cerevisi #ajj #j #ajc #ajj #cd #ajc ,s4 ,carlsbergensis #ajj #aee #aai ,s4 ,thermantitonum #ajj #gf #abd ,assuming that his conclusion that all yeasts which ferment glucose also ferment fructose and mannose is correct1 ,armstrong has drawn attention to the fact that these three hexoses are also related by the possession of a common enolic form 7p4 #ig7 and has suggested that this enolic form is the substance actually fermented to carbon dioxide and alcohol #aijd4 ,the idea that such an intermediate form is the direct subject of fermentation has much to recommend it4 ,in the first place it is almost certain1 as already pointed out1 that the sugars in aqueous solution do exist1 although to a very small extent1 in this enolic form4 ,the slow rate at which equilibrium is established in aqueous solution1 however1 must be taken as definite evidence that under these circumstances the enolic form is only produced very slowly compare ,lowry1 #aijc4 ,this has been used by ,slator #aijh1 #a as an argument against the probability of the preliminary conversion of the sugars into the enolic form before fermentation4 ,it appears1 however1 quite possible that under the influence of the fermenting complex of the yeast-cell1 or of special enzymes1 this change might occur much more rapidly1 p#acd and at different rates with the different sugars4 ,this reaction might in fact control the observed rate of fermentation4 ,this conception affords a simple explanation of the different rates of fermentation of mannose and glucose1 and also of galactose1 the enolic form of which is quite different1 by yeast under different circumstances1 but does not explain the uniformity of rate observed by ,slator for glucose and fructose nor the results with mixtures of sugars4 ,the direct fermentation of a common enolic form is also consistent with the fact that the same hexosephosphate is produced from all three hexoses4 ,slator himself prefers the view that the first stage of fermentation consists in the rapid combination of the sugar with the enzyme1 producing a compound1 which then breaks up at a rate which determines the observed rate of fermentation4 ,this rate will of course vary with the nature of the compound1 so that if two sugars form the same compound they will be fermented at the same rate2 if they form different compounds1 different rates may result4 ,slator supposes that glucose and fructose form the same compound with the enzyme4 ,this1 however1 appears to involve an intramolecular change of the same order as the production of the enolic form1 and moreover is not absolutely essential1 as it is probably sufficient to suppose that the two compounds derived from glucose and fructose are very similar1 although possibly not absolutely identical4 ,mannose and galactose1 on the other hand1 form stereoisomeric compounds1 and the capacity of the fermenting complex to form these compounds may be affected by various agents to a different extent from its capacity for combining with glucose or fructose4 ,a third theory has also been suggested to explain these phenomena1 according to which the various sugars are fermented by different enzymes see ,slator1 #aijh1 #a4 ,the uniformity of the result obtained with glucose and fructose suggests that these two sugars are fermented by the same enzyme 7glucozymase71 mannose and galactose by different ones 7mannozymase and galactozymase74 ,this would afford a simple explanation of the different rates of fermentation for different sugars and of different degrees of sensitiveness towards reagents4 ,if1 however1 a separate and independent mechanism were present for each sugar1 the rate of fermentation of mixtures should be the sum of the rates for the constituents4 ,this1 as shown above1 is not found to be the case1 and it is therefore necessary to suppose1 either that one sugar influences the fermentation of another in some unknown way1 or that only a part of the mechanism of fermentation is specific for the particular sugar4 ,thus the enzyme may be specific and1 the co-enzyme p#ace non-specific1 so that only a certain maximum rate is attainable1 or again1 the supply of free phosphate may be the controlling factor4 ,in the prevailing state of ignorance as to the exact function of the co-enzyme and of the conditions upon which the velocity of fermentation in the cell depends1 it is at present impossible to decide between these various theories1 but they all offer points of attack which justify the hope that much further information can be obtained by experimental inquiry4 ,it will be seen from the foregoing that ,buchner's discovery of zymase has opened a chapter in the history of alcoholic fermentation which is yet far from being completed4 ,in every direction fresh problems present themselves1 and it cannot be doubted that as in the past1 the investigation of the action of the yeast-cell will still prove to be of fundamental importance for our knowledge of the mode in which chemical change is brought about by living organisms4 p#acf ,,bibliography4 ,page of ,text on which reference is made4 ,,abeles1 ,,hans 7#ahih71 _/,zur ,frage der alkoholischen ,ghrung ohne ,hefezellen_/ #ai ,ber41 #ca1 #bbfa-bbfg4 ,,aberson1 ,j4 ,h4 7#aijc71 _/,la fermentation alcoolique_/ #abh ,rec4 trav4 chim41 #bb1 #gh-acb4 ,,ahrens1 ,,felix ,b4 7#aijj71 _/,ein ,beitrag zur zellenfreien ,grung_/ #ai ,zeitsch4 angew4 ,chemie1 #dhc4 ,,ahrens1 ,,felix ,b4 7#aijb71 _/,das ,grungsproblem_/ #i 7,f4 ,enke1 ,stuttgart47 ,,albert1 ,r4 7#ahii1 #a71 _/,ueber knstliche ,anreicherung der ,hefe an ,zymase_/ #bd ,ber41 #cb1 #bcgb-bcgd4 ,,albert1 ,r4 7#ahii1 #b71 _/,erfahrungen bei der ,herstellung von ,hefepresssaft aus unterghriger ,bierhefe der ,versuchs- und ,lehrbrauerei zu ,berlin_/ #cf ,wochensch4 ,brauerei1 #af1 #dhe-dhh4 ,,albert1 ,r4 7#aijj71 _/,einfacher ,versuch zur ,veranschaulichung der ,zymase-,wirkung_/ #ba1 #ci ,ber41 #cc1 #cgge-cggh4 ,,albert1 ,r4 7#aija71 _/,verfahren zur ,herstellung grwirksamer steriler ,dauerhefe mittels ,aceton_/ #ba ,german ,patent ,kl4 #f;a1 ,nr4 #aceece4 ,,albert1 ,r4 and ,w4 7#aija71 _/,chemische ,vorgnge in der abgetteten ,hefezelle_/ #ci ,centr4 ,bakt4 ,par41 ,abt4 ,,ii41 #g1 #gcg-gdb4 ,,albert1 ,r41 und ,e4 ,,buchner 7#aijj1 #a71 _/,hefepresssaft und ,fllungsmittel_/ #ch ,ber41 #cc1 #bff-bga4 ,,albert1 ,r41 und ,e4 ,,buchner 7#aijj1 #b71 _/,hefepresssaft und ,fllungsmittel_/ #ch ,ber41 #cc1 #iga-ige4 ,,albert1 ,r41 ,e4 ,,buchner1 und ,r4 ,,rapp 7#aijb71 ,herstellung von ,dauerhefe mittels ,aceton_/ #ba1 #ci ,ber41 #ce1 #bcgf-bchb4 ,,armstrong1 ,,edward ,,frankland 7#aijd71 _/,studies on enzyme action1 ,,iii4 ,the influence of the products of change on the rate of change conditioned by sucro-clastic enzymes_/ #acc ,proc4 ,roy4 ,soc41 #gc1 #eaf-ebf4 ,,armstrong1 ,,edward ,,frankland 7#aije71 _/,studies on enzyme action1 ,,viii4 ,the mechanism of fermentation_/ #aca1 #acb ,proc4 ,roy4 ,soc41 ,b41 #gf1 #fjj-fje4 ,,armstrong1 ,h4 ,e41 and ,e4 ,f4 ,,armstrong 7#aiaj71 _/,the origin of osmotic effects1 ,,iii4 ,the function of hormones in stimulating enzymic change in relation to narcosis and the phenomena of degenerative and regenerative change in living structures_/ #abg ,proc4 ,roy4 ,soc41 ,b41 #hb1 #ehh-fjb4 ,,ashdown1 ,o4 ,e41 and ,j4 ,t4 ,,hewitt 7#aiaj71 _/,the by-products of alcoholic fermentation_/ #id1 #aaj1 #aae ,j4 ,chem4 ,soc41 #afcf-afdh4 ,,bach1 ,a4 7#aiac71 _/,oxydationsprozesse in der lebenden ,substanz4_/ ,handbuch der ,biochemie1 ,oppenheimer4 ,ergnzungsband #aac 7,g4 ,fischer1 ,jena71 #acc-ahb4 ,,baeyer1 ,,adolf 7#ahgj71 _/,ueber die ,wasserentziehung und ihre ,bedeutung fr das ,pflanzenleben und die ,grung_/ #ii ,ber41 #c1 #fc-ge4 ,,barger1 ,g4 7#aiad71 _/,the simpler natural bases_/ 7this series7 #ij ,,bayliss1 ,w4 ,m4 7#aiad71 _/,the nature of enzyme action_/ #hi1 #aba 7,longmans1 ,green ,co41 ,london47 ,,beijerinck1 ,m4 ,w4 7#ahig71 _/,weitere ,beobachtungen ber die ,octosporushefe_/ #ai ,centr4 ,bakt4 ,par41 ,abt4 ,,ii41 #c1 #ddi-ded4 ,,beijerinck1 ,m4 ,w4 7#aijj71 _/,ueber ,chinonbildung durch ,streptothrix chromogena und ,lebensweise dieses ,mikroben_/ #ai ,centr4 ,bakt4 ,par41 ,abt4 ,,ii41 #f1 #b-ab4 ,,berthelot1 ,m4 7#aheg71 _/,sur la fermentation alcoolique_/ #ad ,compt4 rend41 #dd1 #gjb-gjf4 ,,berthelot1 ,m4 7#ahfj71 _/,sur la fermentation glucosique du sucre de canne_/ #ad ,compt4 rend41 #ej1 #ihj-ihd4 ,,bertrand1 ,g4 7#ahig71 _/,sur l'intervention du manganse dans les oxydations provoques par la laccase_/ #fc ,compt4 rend41 #abd1 #ajcb-ajce4 ,,bertrand1 ,g4 7#aijd71 _/tude ,biochimique de la ,bacterie du ,sorbose_/ #aje ,ann4 ,chim4 ,phys41 7#h71 #c1 #aha-bhh4 ,,berzelius1 ,,jacob 7#ahcf71 _/,einige ,ideen ber eine bei der ,bildung organischer ,verbindungen in der lebenden ,natur wirksame1 aber bisher nicht bemerkte ,kraft_/ #h ,berz4 ,jahresbericht1 #ae1 #bcg-bde4 ,,berzelius1 ,,jacob 7#ahci7 #g ,berz4 ,jahresbericht1 #ah1 #djj-djc4 ,,berzelius1 ,,jacob 7#ahdh7 #i ,berz4 ,jahresbericht1 #bg1 #ejj4 ,,bokorny1 ,,th4 7#aijf71 _/,ueber die ,trennung von ,leben und ,grkraft in der ,hefe_/ #ai ,pflger's ,arch41 #aad1 #ece-edd4 ,,boysen-,,jensen1 ,p4 7#aijh71 _/,die ,zersetzung des ,zuckers whrend des ,respirationsprocesses_/4 7,vorlufige ,mitteilung7 #aje ,ber4 deut4 bot4 ,ges41 #bf;a1 #fff-ffg4 ,,boysen-,,jensen1 ,p4 7#aiaj71 _/,sukkersnderdelingen under ,respirationsprocessen hos hjere ,planter_/ #aje ,dissertation1 ,kbenhavn4 7,h4 ,h4 ,hagerup47 ,,boysen-,,jensen1 ,p4 7#aiad71 _/,die ,zersetzung des ,zuckers bei der alkoholischen ,grung_/ #aje ,biochem4 ,zeitsch41 #eh1 #dea-dff4 ,,bredig1 ,,georg 7#aija71 _/,anorganische ,fermente_/ #cg 7,engelmann1 ,leipzig71 #fh4 ,,brown1 ,,adrian1 ,j4 7#ahib71 _/,influence of oxygen and concentration on alcoholic fermentation_/ #abh ,j4 ,chem4 ,soc41 #fa1 #cfi-che4 ,,brown1 ,,adrian1 ,j4 7#aijb71 _/,enzyme action_/ #aba ,j4 ,chem4 ,soc41 #ha1 #cgc-chh4 ,,bruyn1 ,c4 ,a4 ,,lobry ,,de 7#ahie71 _/,action des alcalis sur les hydrates de carbone1 ,i4_/ 7,expriences provisoires7 #if ,rec4 trav4 chim41 #ad1 #aef-afe4 ,,bruyn1 ,c4 ,a4 ,,lobry ,,de1 and ,w4 ,a4 ,,van ,,ekenstein 7#ahie71 _/,action des alcalis sur les sucres1 ,,ii4 ,transformation rciproque des uns dans les autres des sucres glucose1 fructose et mannose_/ #if ,rec4 trav4 chim41 #ad1 #bjc-baf4 ,,bruyn1 ,c4 ,a4 ,,lobry ,,de1 and ,w4 ,a4 ,,van ,,ekenstein 7#ahif71 _/,action des alcalis sur les sucres1 ,,iii4 ,transformations des sucres sous l'influence de l'hydroxyde de plomb_/ #if ,rec4 trav4 chim41 #ae1 #ib-if4 ,,bruyn1 ,c4 ,a4 ,,lobry ,,de1 and ,w4 ,a4 ,,van ,,ekenstein 7#ahig1 #a71 _/,action des alcalis sur les sucres1 ,,iv4 ,remarques gnrales_/ #if ,rec4 trav4 chim41 #af1 #beg-bfa4 ,,bruyn1 ,c4 ,a4 ,,lobry ,,de1 and ,w4 ,a4 ,,van ,,ekenstein 7#ahig1 #b71 _/,action des alcalis sur les sucres1 ,v4 ,transformation de la galactose1 les tagatoses et la galtose_/ #if ,rec4 trav4 chim41 #af1 #bfb-bgc4 ,,bruyn1 ,c4 ,a4 ,,lobry ,,de1 and ,w4 ,a4 ,,van ,,ekenstein 7#ahig1 #c71 _/,action des alcalis sur les sucres1 ,,vi4 ,la glutose et la pseudo-fructose_/ #if ,rec4 trav4 chim41 #af1 #bgd-bha4 ,,bruyn1 ,c4 ,a4 ,,lobry ,,de1 and ,w4 ,a4 ,,van ,,ekenstein 7#ahig1 #d71 _/,action de l'eau bouillante sur la fructose_/ #if ,rec4 trav4 chim41 #af1 #bhb-bhc4 ,,buchner1 ,,eduard 7#ahig1 #a71 _/,alkoholische ,grung ohne ,hefezellen4_/ ,vorluf4 ,mitt4 #af1 #ah ,ber41 #cj1 #aag-abd4 ,,buchner1 ,,eduard 7#ahig1 #b71 _/,alkoholische ,grung ohne ,hefezellen4_/ ,zweite ,mitt4 #ah1 #bj1 #ba ,ber41 #cj1 #aaaj-aaac4 ,,buchner1 ,,eduard 7#ahih71 _/,ueber zellenfreie ,grung_/ #ah ,ber41 #ca1 #efh-egd4 ,,buchner1 ,,eduard 7#aijj1 #a71 _/,zymase aus getteter ,hefe_/ #ba ,ber41 #cc1 #ccjg-ccaj4 ,,buchner1 ,,eduard 7#aijj1 #b71 _/,bemerkungen zur ,arbeit von ,a4 ,macfadyen1 ,g4 ,h4 ,morris and ,s4 ,rowland ,ueber ausgepresstes ,hefezellplasma 7,buchner's ,zymase7_/ #ba1 #cc ,ber41 #cc1 #ccaa-ccae4 ,,buchner1 ,,eduard 7#aijd71 _/,zur ,geschichte der ,grungstheorien_/ #i ,wochensch4 ,brauerei1 #ba1 #ejg-eaj4 ,,buchner1 ,,eduard 7#aiaj71 _/,sur la fermentation alcoolique du ,sucre_/ #aje1 #ajf ,bull4 ,soc4 ,chim4 ,,buchner1 ,,eduard1 und ,,wilhelm ,,antoni 7#aije1 #a71 _/,weitere ,versuche ber die zellfreie ,grung_/ #cf1 #dj ,zeitsch4 physiol4 ,chem41 #dd1 #bjf-bbh4 ,,buchner1 ,,eduard1 und ,,wilhelm ,,antoni 7#aije1 #b71 _/,existiert ein ,coenzym fr die ,zymase8_/ #fb ,zeitsch4 physiol4 ,chem41 #df1 #acf-aed4 ,,buchner1 ,,eduard1 ,,hans ,,buchner1 und ,,martin ,,hahn 7#aijc71 _/,die ,zymasegrung4 ,untersuchungen ber den ,inhalt der ,hefezellen und die biologische ,seite des ,grungsproblems_/ #ah1 #bj1 #ba1 #bb1 #cj1 #cd1 #ce1 #cf1 #cg1 #ch1 #ci1 #db1 #gg1 #gh1 #aaa1 #abe ,r4 ,oldenbourg1 ,mnchen1 pp4 viii1 #daf4 ,,buchner1 ,,eduard1 und ,,franz ,,ducha,,ek 7#aiji71 _/,ueber fraktionierte ,fllung des ,hefepresssaftes_/ #ch1 #ff ,biochem4 ,zeitsch41 #ae1 #bba-bec4 ,,buchner1 ,,eduard1 und ,,hugo ,,haehn 7#aiji71 _/,ueber das ,spiel der ,enzyme im ,hefepresssaft_/ #fb1 #fh ,biochem4 ,zeitsch41 #ai1 #aia-bah4 ,,buchner1 ,,eduard1 und ,,hugo ,,haehn 7#aiaj1 #a71 _/,ueber eine ,antiprotease im ,hefepresssaft_/ #db ,biochem4 ,zeitsch41 #bf1 #aga-aih4 ,,buchner1 ,,eduard1 und ,,hugo ,,haehn 7#aiaj1 #b71 _/,studien ber den ,phosphorgehalt der ,hefe und einiger ,hefeprparate_/ #fe1 #abc ,biochem4 ,zeitsch41 #bg1 #dah-dbf4 ,,buchner1 ,,eduard1 und ,,robert ,,hoffmann 7#aijg71 _/,einige ,versuche mit ,hefepresssaft_/ #cf ,biochem4 ,zeitsch41 #d1 #bae-bcd4 ,,buchner1 ,,eduard1 und ,f4 ,,klatte 7#aijh71 _/,ueber das ,koenzym des ,hefepresssaftes_/ #fd1 #fg ,biochem4 ,zeitsch41 #h1 #ebj-eeg4 ,,buchner1 ,,eduard1 und ,,jakob ,,meisenheimer 7#aijd71 _/,die chemischen ,vorgnge bei der alkoholischen ,grung_/ #ih1 #ajj1 #ajb ,ber41 #cg1 #dag-dbh4 ,,buchner1 ,,eduard1 und ,,jakob ,,meisenheimer 7#aije71 _/,die chemischen ,vorgnge bei der alkoholischen ,grung4_/ 7,zweite ,mitteilung7 #ig1 #ih1 #ajj1 #ajb ,ber41 #ch1 #fbj-fcj4 ,,buchner1 ,,eduard1 und ,,jakob ,,meisenheimer 7#aijf71 _/,die chemischen ,vorgnge bei der alkoholischen ,grung4_/ 7,dritte ,mitteilung7 #ca1 #hg1 #ie1 #ajb1 #ajd ,ber41 #ci1 #cbja-cbah4 ,,buchner1 ,,eduard1 und ,,jakob ,,meisenheimer 7#aijh71 _/,ueber ,buttersuregrung_/ #aaj ,ber41 #da1 #adaj-adai4 ,,buchner1 ,,eduard1 und ,,jakob ,,meisenheimer 7#aiji71 _/,ueber die ,rolle der ,milchsure bei der alkoholischen ,grung des ,zuckers_/ #ajj1 #ajb1 #ajc ,zeitsch4 wiss4 ,landwirtschaft1 #ch1 ,ergnzungsband ,v41 #bfe-bhh4 ,,buchner1 ,,eduard1 und ,,jakob ,,meisenheimer 7#aiaj71 _/,die chemischen ,vorgnge bei der alkoholischen ,grung4_/ 7,,iv4 ,mitteilung7 #ajc1 #ajd1 #aje1 #ajf1 #aae ,ber41 #dc1 #aggc-agie4 ,,buchner1 ,,eduard1 und ,,jakob ,,meisenheimer 7#aiab71 _/,die chemischen ,vorgnge bei der alkoholischen ,grung_/ #aje1 #ajf ,ber41 #de1 #afcc-afdc4 ,,buchner1 ,,eduard1 ,j4 ,,meisenheimer1 und ,h4 ,,schade 7#aijf71 _/,zur ,vergrung des ,zuckers ohne ,enzyme_/ #aad ,ber41 #ci1 #dbag-dbca4 ,,buchner1 ,,eduard1 und ,,sigurd ,,mitscherlich 7#aijd71 _/,herstellung glykogenarmer ,hefe und deren ,anwendung zum ,zuckernachweis im ,harn_/ #ci ,zeitsch4 physiol4 ,chem41 #db1 #eed-efb4 ,,buchner1 ,,eduard1 und ,,rudolf ,,rapp 7#ahig71 _/,alkoholische ,grung ohne ,hefezellen_/ #ai1 #cd1 #cf1 #gg ,ber41 #cj1 #bffh-bfgh4 ,,buchner1 ,,eduard1 und ,,rudolph ,,rapp 7#ahih1 #a71 _/,alkoholische ,grung ohne ,hefezellen_/ #ae1 #ei1 #gg ,ber41 #ca1 #bji-bag4 ,,buchner1 ,,eduard1 und ,,rudolf ,,rapp 7#ahih1 #b71 _/,alkoholische ,grung ohne ,hefezellen4_/ 7#e ,mitteilung7 #cf1 #gg ,ber41 #ca1 #ajhd-ajij4 ,,buchner1 ,,eduard1 und ,,rudolf ,,rapp 7#ahih1 #c71 _/,alkoholische ,grung ohne ,hefezellen4_/ 7#f ,mitteilung7 #cb1 #cf1 #gg ,ber41 #ca1 #ajij-ajid4 ,,buchner1 ,,eduard1 und ,,rudolf ,,rapp 7#ahih1 #d71 _/,alkoholische ,grung ohne ,hefezellen4_/ 7#g ,mitteilung7 #ch ,ber41 #ca1 #aeca-aecc4 ,,buchner1 ,,eduard1 und ,,rudolf ,,rapp 7#ahii1 #a71 _/,alkoholische ,grung ohne ,hefezellen4_/ 7#h ,mitteilung7 #cf ,ber41 #cb1 #abg-acg4 ,,buchner1 ,,eduard1 und ,,rudolf ,,rapp 7#ahii1 #b71 _/,alkoholische ,grung ohne ,hefezellen4_/ 7#i ,mitteilung7 #cb1 #db1 #gg ,ber41 #cb1 #bjhf-bjid4 ,,buchner1 ,,eduard1 und ,,rudolf ,,rapp 7#aija71 _/,alkoholische ,grung ohne ,hefezellen4_/ 7#aj ,mitteilung7 #ch ,ber41 #cd1 #aebc-aecj4 ,,buchner1 ,,eduard1 und ,,siegfried ,,skraup 7#aiad71 _/,ist die ,enzym-,theorie der ,grung einzuschrnken8_/ #abg ,ber41 #aiad1 #dg1 #hec-hgj4 ,,buchner1 ,,eduard1 and ,,albert ,,spitta 7#aijb71 _/,zymasebildung in der ,hefe_/ #ch ,ber41 #ce1 #agjc-agjf4 ,,buchner1 ,,hans 7#ahig71 _/,die ,bedeutung der aktiven lslichen ,zellprodukte fr den ,chemismus der ,zelle_/ #ah ,mnchen4 med4 ,wochensch4 7,no4 #ab71 #dd1 #cjj-cjb1 and #cbb4 ,,cagniard-,,latour 7#ahch71 _/,mmoire sur la ,fermentation vineuse4_/ 7,prsent l',acadmie des ,sciences1 le #ab juin1 #ahcg7 #e ,ann4 ,chim4 ,phys41 #fh1 #bjf-bbb4 ,,cavendish1 ,,henry 7#agff71 _/,three papers containing experiments on factitious air4 ,part ,,iii4 ,containing experiments on the air1 produced by fermentation and putrefaction4_/ 7,read #ac ,nov41 #agff7 #b ,phil4 ,trans41 #age-ahd4 ,,chick1 ,,frances 7#aiab71 _/,die vermeintliche ,dioxyacetonbildung whrend der alkoholischen ,grung und die ,wirkung von ,tierkohle und von ,methylphenylhydrazin auf ,dioxyaceton_/ #aje ,biochem4 ,zeitsch41 #dj1 #dgi-dhe4 ,,clowes1 ,,george ,h4 ,a4 7#aiji71 _/,a critical study of the conditions under which zymase and its associated coenzyme bring about alcoholic fermentation_/ #abb ,proc4 ,exper4 ,biol4 and ,medicine1 #f1 #dd-df4 ,,colin 7#ahbe71 _/,mmoire sur la ,fermentation du ,sucre_/4 7,lu l',acadmie des ,sciences1 le #cast janvier1 #ahbe7 #e ,ann4 ,chim4 ,phys41 #bh1 #abh-adb4 ,,cremer1 ,m4 7#ahii71 _/,ueber ,glykogenbildung im ,hefepresssaft_/ #aaf ,ber41 #cb1 #bjfb-bjfd4 ,,dakin1 ,h4 ,d4 7#aijc71 _/,the hydrolysis of ethyl mandelate by lipase_/ #hi ,proc4 ,chem4 ,soc41 #ai1 #afa4 ,,dakin1 ,h4 ,d4 7#aije71 _/,the fractional hydrolysis of optically inactive esters by lipase ,part ,,ii4_/ #hi ,j4 ,physiol41 #cb1 #aii-bjf4 ,,dakin1 ,h4 ,d4 7#aijh71 _/,the oxidation of leucin1 -amido-isovaleric acid and of -amido-n-valeric acid with hydrogen peroxide_/ #ic ,j4 ,biol4 ,chem41 #d1 #fc-gf4 ,,dakin1 ,h4 ,d4 7#aiab71 _/,oxidations and reductions in the animal body_/ 7this series7 #ib ,,dakin1 ,h4 ,d41 and ,h4 ,w4 ,,dudley 7#aiac71 _/,the interconversion of -amino-acids1 -hydroxyacids1 and -ketonic aldehydes4 ,part ,,ii4_/ #ic ,j4 ,biol4 ,chem41 #ae1 #abg-adc4 ,,delbr,,ck1 ,,max 7#ahig71 _/,alkoholische ,grung ohne ,hefezellen_/ #ai ,wochensch4 ,brauerei1 #ad1 #cfc-cfd4 ,,desmazi,,res 7#ahbf7 #e ,annales des ,sciences naturelles1 #aj1 #db-fg4 ,,dixon1 ,,henry ,h41 and ,w4 ,r4 ,g4 ,,atkins 7#aiac71 _/,the extraction of zymase by means of liquid air4_/ 7,preliminary ,note7 #be1 #bf ,sci4 ,proc4 ,roy4 ,dublin ,soc41 #ad1 #a-h4 ,,ducha,,ek1 ,,franz 7#aiji71 _/,einwirkung verschiedener ,antiseptika auf die ,enzyme des ,hefepresssaftes_/ #cf ,biochem4 ,zeitsch41 #ah1 #baa-bbg4 ,,duclaux1 ,e4 7#ahhf71 _/,sur les transformations chimiques provoques par la lumire solaire_/ #ih ,compt4 rend41 #ajc1 #hha-hhb4 ,,duclaux1 ,e4 7#ahic71 _/,sur les analogies entre les procs de fermentation et de combustion solaire_/ #ih ,ann4 ,inst4 ,pasteur1 #g1 #gea-ged4 ,,duclaux1 ,e4 7#ahif71 _/tudes sur l'action solaire_/4 7,premier ,mmoire7 #ih ,ann4 ,inst4 ,pasteur1 #aj1 #abi-afh4 ,,duclaux1 ,e4 7#ahii7 #aba ,mikrobiologie1 #b1 #adb4 ,,dumas1 ,,jean ,,baptiste 7#ahgd71 _/,recherches sur la fermentation alcoolique_/ #abh ,ann4 ,chim4 ,phys41 #c1 #eg-ajh4 ,,ehrlich1 ,,felix 7#aijc71 _/,ueber neue stickstoffhaltige ,bestandteile der ,zuckerablufe_/ #hf ,zeitsch4 ,verein4 ,rbenzucker-,ind41 #hji-hbi4 ,,ehrlich1 ,,felix 7#aijd1 #a71 _/,ueber das natrliche ,isomere des ,leucins_/ #hf ,ber41 #cg1 #ahji-ahdj4 ,,ehrlich1 ,,felix 7#aijd1 #b71 _/,ueber den neuen optischaktiven ,nichtzucker1 das ,isoleucin_/ #hf ,zeitsch4 ,verein4 ,rbenzucker-,ind41 #gge-hjc4 ,,ehrlich1 ,,felix 7#aije71 _/,ueber die ,entstehung des ,fuselles_/ #hg ,zeitsch4 ,verein4 ,rbenzucker-,ind41 #eci-efg4 ,,ehrlich1 ,,felix 7#aijf1 #a71 _/,ueber eine ,methode zur ,spaltung racemischer ,aminosuren mittels ,hefe_/ #hi ,biochem4 ,zeitsch41 #a1 #h-ca2 ,zeitsch4 ,verein4 ,rbenzucker-,ind41 #hdj-hfj4 ,,ehrlich1 ,,felix 7#aijf1 #b71 _/,verfahren zur ,gewinnung von ,fusellen und dessen ,bestandteilen_/ #hg ,german ,patent ,kl4 #abj1 ,nr4 #aggagd1 vom4 #a1 #d1 #aije 7#ag ,nov41 #aijf74 ,,ehrlich1 ,,felix 7#aijf1 #c71 _/,die chemischen ,vorgnge bei der ,hefegrung_/ #hg1 #ij1 #id ,biochem4 ,zeitsch41 #b1 #eb-hj2 ,zeitsch4 ,verein4 ,rbenzucker-,ind41 #aade-aafh4 ,,ehrlich1 ,,felix 7#aijf1 #d71 _/,zur ,frage der ,fusellbildung der ,hefe_/ #hg ,ber41 #ci1 #djgb-djge4 ,,ehrlich1 ,,felix 7#aijg1 #a71 _/,ueber die ,bedingungen der ,fusellbildung und ber ihren ,zusammenhang mit dem ,eiweissaufbau der ,hefe_/ #hg1 #id ,ber41 #dj1 #ajbg-ajdg2 ,zeitsch4 ,verein4 ,rbenzucker-,ind41 #aijg1 #dfa4 ,,ehrlich1 ,,felix 7#aijg1 #b71 _/,ueber das natrliche ,isomere des ,leucins_/ #hf ,ber41 #dj1 #bech-befb4 ,,ehrlich1 ,,felix 7#aijg1 #c71 _/,die ,rolle des ,eiweisses und der ,eiweissabbauprodukte bei der ,grung_/ #hg ,jahrb4 d4 ,versuchs u4 ,lehranstalt f4 ,brauerei in ,berlin1 #aj1 #eae-ebi4 ,,ehrlich1 ,,felix 7#aijh71 _/,ueber eine ,synthese des ,isoleucins_/ #hf ,ber41 #da1 #adec-adeh2 ,zeitsch4 ,verein4 deutsch4 ,zuckerind41 #aijh1 #ebh-ecc4 ,,ehrlich1 ,,felix 7#aiji71 _/,ueber die ,entstehung der ,bernsteinsure bei der alkoholischen ,grung_/ #hi ,biochem4 ,zeitsch41 #ah1 #cia-dbc4 ,,ehrlich1 ,,felix 7#aiaa1 #a71 _/,ueber die ,vergrung des ,tyrosins zu p-,oxyphenylethyl alkohol4 7,tyrosol7_/ #hh ,ber41 #dd1 #aci-adg4 ,,ehrlich1 ,,felix 7#aiaa1 #b71 _/,ueber die ,bildung des ,plasmaeiweisses bei ,hefen und ,schimmelpilzen_/ #hi ,biochem4 ,zeitsch41 #cf1 #dgg-dig4 ,,ehrlich1 ,,felix 7#aiab71 _/,ueber ,tryptophol 7-,indolylthylalkohol71 ein neues ,grprodukt der ,hefe aus ,aminosuren_/ #hh ,ber41 #de1 #hhc-hhi4 ,,ehrlich1 ,,felix1 and ,k4 ,a4 ,,jacobsen 7#aiaa71 _/,ueber die ,umwandlung von ,aminosuren in ,oxysuren durch ,schimmelpilze_/ #hi ,ber41 #dd1 #hhh-hig4 ,,ehrlich1 ,,felix1 and ,p4 ,,pistschimuka 7#aiab1 #a71 _/,ueberfuhrung von ,aminen in ,alkohole durch ,hefe und ,schimmelpilze_/ #ia ,ber41 #de1 #ajjf-ajab4 ,,ehrlich1 ,,felix1 and ,p4 ,,pistschimuka 7#aiab1 #b71 _/,synthesen des ,tyrosols und seine ,umwandlung in ,hordenin_/ #hh ,ber41 #de1 #bdbh-bdcg4 ,,ehrlich1 ,,felix 7mit ,a4 ,,wendel7 7#aijh1 #a71 _/,ueber die ,spaltung racemischer ,amidosuren mittels ,hefe1 ,,ii4_/ #hi ,biochem4 ,zeitsch41 #h1 #dch-dff4 ,,ehrlich1 ,,felix1 und ,,adolph ,,wendel 7#aijh1 #b71 _/,zur ,kenntnis der ,leucinfraktion des ,eiweisses_/ #hf ,biochem4 ,zeitsch41 #h1 #cii-dcg4 ,,emmerling1 ,o4 7#ahii71 _/,das ,verhalten von ,glycerinaldehyd und ,dioxyaceton gegen ,hefe_/ #ajd ,ber41 #cb1 #edb-edd4 ,,emmerling1 ,o4 7#aijd71 _/,ueber den ,ursprung der ,fuselle_/ #hf ,ber41 #cg1 #cece-cech4 ,,emmerling1 ,o4 7#aije71 _/,ueber den ,ursprung der ,fuselle_/ #hf ,ber41 #ch1 #iec-ief4 ,,euler1 ,,hans 7#aije71 _/,chemische ,dynamik der zellfreien ,grung_/ #abj ,zeitsch4 physiol4 ,chem41 #dd1 #ec-gc4 ,,euler1 ,,hans 7#aiab1 #a71 _/,ueber die ,wirkungsweise der ,phosphatese_/4 7#c ,mitteilung7 #dg1 #eh ,biochem4 ,zeitsch41 #da1 #bae-bbc4 ,,euler1 ,,hans 7#aiab1 #b71 _/,verhalten der ,kohlenhydratphosphorsure-ester im ,tierkrper4 ,nach ,versuchen von ,e4 ,thorin und ,d4 ,johansson_/ #ea ,zeitsch4 physiol4 ,chem41 #gi1 #cge-cig4 ,,euler1 ,,hans 7#aiad71 _/,ueber die ,rolle des ,glykogens bei der ,grung durch lebende ,hefe_/ #aaf ,zeitsch4 physiol4 ,chem41 #hi1 #ccg-cdd4 ,,euler1 ,,hans1 and ,b,,ckstr,m1 ,,helma 7#aiab71 _/,zum ,kenntnis der ,hefegrung_/4 7#b ,mitteilung7 #dg1 #fh1 #acj ,zeitsch4 physiol4 ,chem41 #gg1 #cid-dja4 ,,euler1 ,,hans1 and ,,th4 ,,berggren 7#aiab71 _/,ueber die primre ,umwandlung der ,hexosen bei der alkoholischen ,grung_/ #cb1 #acj ,zeitsch4 ,grungsphysiol41 #a1 #bjc-bah4 ,,euler1 ,,hans1 and ,,henry ,,cassel 7#aiac71 _/,ueber ,katalysatoren der alkoholischen ,grung_/4 ,vorlufige ,mitteilung #acj ,zeitsch4 physiol4 ,chem41 #hf1 #abb-abi4 ,,euler1 ,,hans1 and ,a4 ,,fodor 7#aiaa71 _/,ueber ein ,zwischenprodukt der alkoholischen ,grung_/ #dg1 #dh1 #di1 #ej1 #aje ,biochem4 ,zeitsch41 #cf1 #dja-daj4 ,,euler1 ,,hans1 and ,,yngve ,,funke 7#aiab71 _/,ueber die ,spaltung der ,kohlenhydratphosphorsure-ester_/ #ea ,zeitsch4 physiol4 ,chem41 #gg1 #dhh-dif4 ,,euler1 ,,hans1 and ,,david ,,johansson 7#aiab1 #a71 _/,umwandlung des ,zuckers und ,bildung der ,kohlensure bei der alkoholischen ,grung_/ #cb ,zeitsch4 physiol4 ,chem41 #gf1 #cdg-ced4 ,,euler1 ,,hans1 and ,,david ,,johansson 7#aiab1 #b71 _/,untersuchungen ber die chemische ,zusammensetzung und ,bildung der ,enzyme4 ,,iv4 ,ueber die ,anpassung einer ,hefe an ,galaktose_/ #acc ,zeitsch4 physiol4 ,chem41 #gh1 #bdf-bfe4 ,,euler1 ,,hans1 and ,,david ,,johannson 7#aiab1 #c71 _/,ueber den ,einfluss des ,toluols auf die ,zymase und auf die ,phosphatese_/ #abe ,zeitsch4 physiol4 ,chem41 #hj1 #age-aha4 ,,euler1 ,,hans1 and ,,david ,,johansson 7#aiab1 #d71 _/,versuche ber die enzymatische ,phosphatbindung_/ #dg1 #eg ,zeitsch4 physiol4 ,chem41 #hj1 #bje-baa4 ,,euler1 ,,hans1 and ,,david ,,johansson 7#aiac71 _/,ueber die ,reaktionsphasen der alkoholischen ,grung_/ #dg1 #eb1 #ed1 #gc ,zeitsch4 physiol4 ,chem41 #he1 #aib-bjh4 ,,euler1 ,,hans1 and ,,sixten ,,kullberg 7#aiaa1 #a71 _/,untersuchungen ber die chemische ,zusammensetzung und ,bildung der ,enzyme_/ #abd1 #abf ,zeitsch4 physiol4 ,chem41 #ga1 #ad-cj4 ,,euler1 ,,hans1 and ,,sixten ,,kullberg 7#aiaa1 #b71 _/,ueber das ,verhalten freier und an ,protoplasma gebundener ,hefenenzyme_/ #abd1 #abf ,zeitsch4 physiol4 ,chem41 #gc1 #he-ajj and partly in ,arkiv4 ,kem4 ,min4 ,geol41 #d1 ,no4 #ac1 #a-aa4 ,,euler1 ,,hans1 and ,,sixten ,,kullberg 7#aiaa1 #c71 _/,ueber die ,wirkungsweise der ,phosphatese_/ #dg1 #eh1 #abb ,zeitsch4 physiol4 ,chem41 #gd1 #ae-bh4 ,,euler1 ,,hans1 and ,,gunnar ,,lundeqvist 7#aiaa71 _/,zur ,kenntnis der ,hefegrung_/ #aca ,zeitsch4 physiol4 ,chem41 #gb1 #ig-aab4 ,,euler1 ,,hans1 and ,,hjalmar ,,ohls,n 7#aiaa71 _/,ueber den ,einfluss der ,temperatur auf die ,wirkung der ,phosphatese_/ #dg1 #eg1 #eh ,biochem4 ,zeitsch41 #cg1 #cac-cbj4 ,,euler1 ,,hans1 and ,,hjalmar ,,ohls,n 7#aiab71 _/,ueber die ,wirkungsweise der ,phosphatese1 ,,ii_/ #dg1 #eg ,zeitsch4 physiol4 ,chem41 #gf1 #dfh-dgg4 ,,euler1 ,,hans1 and ,,beth ,,af4 ,,ugglas 7#aiaa71 _/,untersuchungen ber die chemische ,zusammensetzung und ,bildung der ,enzyme4_/ 7#b ,mitteilung7 #abe1 #abf ,zeitsch4 physiol4 ,chem41 #gj1 #bgi-bij4 ,,fernbach1 ,a4 7#aiaj71 _/,sur la dgradation biologique des hydrates de carbone_/ #ajg ,compt4 rend41 #aea1 #ajjd-ajjf4 ,,fernbach1 ,a41 and ,,schoen ,m4 7#aiac71 _/,l'acide pyruvique1 produit de la vie de la levure_/ #aji ,compt4 rend41 #aeg1 #adgh-adhj4 ,,fischer1 ,,emil1 und ,,julius ,,tafel 7#ahhh71 _/,oxydation des ,glycerins_/ #ajd ,ber41 #ba1 #bfcd-bfcg4 ,,fischer1 ,,emil1 und ,,julius ,,tafel 7#ahhi71 _/,oxydation des ,glycerins1 ,,ii4_/ #ajd ,ber41 #bb1 #ajf-aaj4 ,,fischer1 ,,emil1 und ,,hans ,,thierfelder 7#ahid71 _/,verhalten der verschiedenen ,zucker gegen reine ,hefen_/ #hi ,ber41 #bg1 #bjca-bjcg4 ,,fischer1 ,,hugo 7#aijc71 _/,ueber ,enzymwirkung und ,grung_/ #ai ,centr4 ,bakt4 ,par41 ,abt4 ,,ii41 #aj1 #edg-h4 ,,fitz1 ,,alb4 7#ahhj71 _/,ueber ,spaltpilzgrungen_/4 7#f ,mitteilung7 #ih ,ber41 #ac1 #acji-acab4 ,,franzen1 ,,hartwig1 and ,o4 ,,steppuhn 7#aiaa71 _/,ein ,beitrag zur ,kenntnis der alkoholischen ,grung_/ #aae ,ber41 #dd1 #biae-biai4 ,,franzen1 ,,hartwig1 and ,o4 ,,steppuhn 7#aiab1 #a71 _/,vergrung und ,bildung der ,ameisensure durch ,hefen_/ #ajc1 #aae ,zeitsch4 physiol4 ,chem41 #gg1 #abi-ahb4 ,,franzen1 ,,hartwig1 and ,o4 ,,steppuhn 7#aiab1 #b71 _/,berichtigung zu der ,abhandlung3 ,ueber die ,vergrung und ,bildung der ,ameisensure durch ,hefen_/ #aae ,zeitsch4 physiol4 ,chem41 #gh1 #afd4 ,,gay-,,lussac1 ,,louis ,,joseph 7#ahaj71 _/,extrait d'un ,mmoire sur la ,fermentation_/4 7,lu l',inst41 #c ,dec1 #ahaj7 #d ,ann4 ,chim4 ,phys41 #gf1 #bde-bei4 ,,geret1 ,l41 und ,m4 ,,hahn 7#ahih1 #a71 _/,zum ,nachweis des im ,hefepresssaft enthaltenen proteolytischen ,enzyms_/ #bj ,ber41 #ca1 #bjb-bje4 ,,geret1 ,l41 und ,m4 ,,hahn 7#ahih1 #b71 _/,weitere ,mitteilungen ber das im ,hefepresssaft enthaltene proteolytische ,enzym_/ #bj ,ber41 #ca1 #bcce-bcdd4 ,,geret1 ,l41 und ,m4 ,,hahn 7#aijj71 _/,ueber das ,hefe-endotrypsin_/ #bj ,zeitsch4 ,biologie1 #dj1 #aag-agb4 ,,gerhardt1 ,,charles 7#ahef71 _/,trait de ,chimie ,organique_/1 #d1 #ecg-edf #aj1 #ae ,,giglioli1 ,j4 7#aiaa71 _/,della probabile funzione degli olii essenziali e di altri prodotti volatili delle piante1 quale causa di movemento dei succhi nei tessuli viventi_/ #bf ,atti4 ,r4 ,accad4 ,lincei1 #bj1 ,,ii41 #cdi-cfa4 ,,green1 ,j4 ,,reynolds 7#ahig71 _/,the supposed alcoholic enzyme in yeast_/ #ai ,annals of ,botany1 #aa1 #eee-efb4 ,,green1 ,j4 ,,reynolds 7#ahih71 _/,the alcohol-producing enzyme of yeast_/ #ai ,annals of ,botany1 #ab1 #dia-dig4 ,,gromoff1 ,t41 und ,o4 ,,grigorieff 7#aijd71 _/,die ,arbeit der ,zymase und der ,endotryptase in den abgetteten ,hefezellen unter verschiedenen ,verhltnissen_/ #cf ,zeitsch4 physiol4 ,chem41 #db1 #bii-cbi4 ,,gruber1 ,m4 7#aijh71 _/,eduard ,buchner_/ #ah ,mnchen1 med4 ,wochensch41 #cdb4 ,,gr,,ss1 ,j4 7#aijd71 _/,untersuchungen ber die ,atmung und ,atmungsenzyme der ,hefe_/ #aaa ,zeitsch4 ,ges4 ,brauwesen1 #bg1 #fhi4 ,,gr,,ss1 ,j4 7#aijh1 #a71 _/,ueber den ,nachweis mittelst ,chromogramm-,methode dass die ,hydrogenase aktiv bei der ,alkoholgrung beteiligt ist_/ #aaa ,ber4 deutsch1 botan4 ,ges41 #bf;,a1 #aia-aif4 ,,gr,,ss1 ,j4 7#aijh1 #b71 _/,hydrogenase oder ,reduktase8_/ #aaa ,ber4 deutsch1 botan4 ,ges41 #bf;,a1 #fbg-fcj1 ,abstract ,j4 ,inst4 ,brewing1 #aiji1 #cdd4 ,,hahn1 ,,martin 7#ahih71 _/,das proteolytische ,enzym des ,hefepresssaftes_/ #bj ,ber41 #ca1 #bjj-bja4 ,,hahn1 ,,martin 7#aijh71 _/,zur ,geschichte der ,zymaseentdeckung_/ #ah ,mnchen4 med4 ,wochensch41 #eae4 ,,hanriot1 ,m4 7#ahhe1 #ahhf71 _/,sur la dcomposition pyrogne des acides de la srie grasse_/ #ih ,bull4 ,soc4 ,chim41 #dc1 #dag2 #de1 #gi-hj4 ,,harden1 ,,arthur 7#aija71 _/,the chemical action of ,bacillus coli communis and similar organisms on carbohydrates and allied compounds_/ #ij1 #aae ,j4 ,chem4 ,soc41 #gi1 #fab-fbh4 ,,harden1 ,,arthur 7#aijc71 _/,ueber alkoholische ,grung mit ,hefepresssaft 7,buchner's ,zymase7 bei ,gegenwart von ,blutserum_/ #bj1 #da ,ber41 #cf1 #gae-gaf4 ,,harden1 ,,arthur 7#aije71 _/,zymase and alcoholic fermentation_/ #db1 #ajc ,j4 ,inst4 ,brewing1 #aa1 ,no4 #a4 ,,harden1 ,,arthur 7#aiaj71 _/,recent researches on alcoholic fermentation_/ #abe ,j4 ,inst4 ,brewing1 #af1 #fbc-fci4 ,,harden1 ,,arthur 7#aiac71 _/,the enzymes of washed zymin and dried yeast_/ 7,lebedeff74 _/,i4 ,carboxylase_/ #hb1 #hc ,biochem4 ,j41 #g1 #bad-bag4 ,,harden1 ,,arthur1 and ,,dorothy ,,norris 7#aiab71 _/,the bacterial production of acetylmethylcarbinol and #b-c butylene glycol from various substances_/ #aaj ,proc4 ,roy4 ,soc41 ,b41 #hd1 #dib-dii4 ,,harden1 ,,arthur1 and ,,roland ,v4 ,,norris 7#aiaj71 _/,the fermentation of galactose by yeast and yeast-juice4_/ 7,preliminary ,communication7 #cb1 #acc ,proc4 ,roy4 ,soc41 ,b41 #hb1 #fde-fdi4 ,,harden1 ,,arthur1 and ,,roland ,v4 ,,norris 7#aiad71 _/,the enzymes of washed zymin and dried yeast_/ 7,lebedeff74 _/,,ii4 ,reductase_/ #fh1 #aaa1 #aac ,biochem4 ,j41 #h1 #ajj-ajf4 ,,harden1 ,,arthur1 and ,s4 ,g4 ,,paine 7#aiab71 _/,the action of dissolved substances on the autofermentation of yeast_/ #abg ,proc4 ,roy4 ,soc41 ,b41 #hd1 #ddh-dei4 ,,harden1 ,,arthur1 and ,,robert ,,robison 7#aiad71 _/,a new phosphoric ester obtained by the aid of yeast-juice4_/ 7,preliminary ,note7 #dh ,proc4 ,chem4 ,soc41 #cj1 #af-ag4 ,,harden1 ,,arthur1 and ,,sydney ,,rowland 7#aija71 _/,autofermentation and liquefaction of pressed yeast_/ #abf ,j4 ,chem4 ,soc41 #gi1 #abbg-abce4 ,,harden1 ,,arthur1 ,j4 ,,thompson1 and ,w4 ,j4 ,,young 7#aiaj71 _/,apparatus for the collection of gases evolved in fermentation_/ #bh ,biochem4 ,j41 #e1 #bcj-bce4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aijb71 _/,glycogen from yeast_/ #cc ,j4 ,chem4 ,soc41 #ha1 #abbd-abcc4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aijd71 _/,grversuche mit ,presssaft aus obergriger ,hefe_/ #cj1 #cc1 #ce ,ber41 #cg1 #ajeb-ajgj4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aije1 #a71 _/,the alcoholic ferment of yeast-juice_/ #da1 #db1 #ei ,j4 ,physiol41 #cb4 ,proceedings of #ab ,november1 #aijd4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aije1 #b71 _/,the influence of phosphates on the fermentation of glucose by yeast-juice4_/ 7,preliminary communication1 #a ,june1 #aije7 #db1 #dg ,proc4 ,chem4 ,soc41 #ba1 #ahi-aia4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aijf1 #a71 _/,the alcoholic ferment of yeast-juice_/ #dc ,proc4 ,roy4 ,soc41 ,b41 #gg1 #dje-dbj4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aijf1 #b71 _/,the alcoholic ferment of yeast-juice4 ,part ,,ii4 ,the co-ferment of yeast-juice_/ #ei1 #fb ,proc4 ,roy4 ,soc1 ,b41 #gh1 #cfi-cge4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aijf1 #c71 _/,influence of sodium arsenate on the fermentation of glucose by yeast-juice_/4 7,preliminary notice7 #cg1 #ge ,proc4 ,chem4 ,soc1 #bb1 #bhc-bhd4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aijg7 #fe ,biochem4 ,centr41 #f1 #hhh4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aijh1 #a71 _/,the alcoholic ferment of yeast-juice4 ,part ,,iii4 ,the function of phosphates in the fermentation of glucose by yeast-juice_/ #dg1 #ec1 #ga ,proc4 ,roy4 ,soc41 ,b41 #hj1 #bii-caa4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aijh1 #b71 _/,the fermentation of mannose and lvulose by yeast-juice_/4 7,preliminary note7 #gc ,proc4 ,chem4 ,soc41 #bd1 #aae-aag4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aiji71 _/,the alcoholic ferment of yeast-juice4 ,part ,,iv4 ,the fermentation of glucose1 mannose1 and fructose by yeast-juice_/ #cb1 #dd1 #dg1 #gc ,proc4 ,roy4 ,soc41 ,b41 #ha1 #ccf-cdg4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aiaj1 #a71 _/,the function of phosphates in alcoholic fermentation_/ #df1 #ajf ,centr4 ,bakt4 ,par41 ,abt4 ,,ii41 #bf1 #agh-ahd4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aiaj1 #b71 _/,the alcoholic ferment of yeast-juice4 ,part ,v4 ,the function of phosphates in alcoholic fermentation_/ #dd1 #eb1 #ef ,proc4 ,roy4 ,soc41 ,b41 #hb1 #cba-ccj4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aiaa1 #a71 _/,the alcoholic ferment of yeast-juice4 ,part ,,vi4 ,the effect of arsenates and arsenites on the fermentation of the sugars by yeast-juice_/ #ef1 #ge1 #gg1 #gi ,proc4 ,roy4 ,soc41 ,b41 #hc1 #dea-dge4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aiaa1 #b71 _/,ueber die ,zusammensetzung der durch ,hefepresssaft gebildeten ,hexosephosphorsure ,i_/4 #dg ,biochem4 ,zeitsch41 #cb1 #agc-agf4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aiab71 _/,der ,mechanismus der alkoholischen ,grung_/ #df1 #ajf1 #ajh ,biochem4 ,zeitsch41 #dj1 #deh-dgh4 ,,harden1 ,,arthur1 and ,w4 ,j4 ,,young 7#aiac71 _/,the enzymatic formation of polysaccharides by yeast preparations_/ #ca1 #acj ,biochem4 ,j41 #g1 #fcj-fcf4 ,,harding1 ,,victor ,j4 7#aiab71 _/,the action of enzymes on hexosephosphate_/ #ea ,proc4 ,roy4 ,soc41 ,b41 #he1 #dah-dbb4 ,,helmholtz1 ,,hermann ,,ludwig 7#ahdc71 _/,ueber das ,wesen der ,fulnis und ,grung_/ #aj ,arch4 ,anat4 ,physiol4 ,joh4 ,mller1 #e1 #dec-dfb4 ,,herzog1 ,r4 ,o4 7#aijb71 _/,ueber alkoholische ,grung1 ,i4_/ #abj ,zeitsch4 physiol4 ,chem41 #cg1 #adi-afj4 ,,herzog1 ,r4 ,o4 7#aijd71 _/,ueber die ,geschwindigkeit enzymatischer ,reaktionen_/ #abj ,zeitsch1 physiol4 ,chem41 #da1 #daf4 ,,hoppe-,,seyler1 ,f4 7#ahgf71 _/,ueber die ,processe der ,grungen und ihre ,beziehungen zum ,leben der ,organismen_/ #ad ,pflger's ,archiv1 #ab1 #a-ag4 ,,hoppe-,,seyler1 ,f4 7#ahgg71 _/,ueber ,grungen4 ,antwort auf einen ,angriff des ,herrn ,moritz ,traube_/ #ad ,ber41 #aj1 #fic-fie4 ,,iwanoff1 ,,leonid 7#aije71 _/,ueber ,umwandlungen des ,phosphors in der ,pflanze_/ #dg ,s4 ,travaux de la ,soc4 des ,naturalistes de ,st4 ,petersburg1 #cd4 ,,iwanoff1 ,,leonid 7#aijg71 _/,ueber die ,synthese der phospho-organischen ,verbindungen in abgetteten ,hefezellen_/ #dg ,zeitsch4 physiol4 ,chem41 #ej1 #bha-bhh4 ,,iwanoff1 ,,leonid 7#aiji1 #a71 _/,ueber die ,bildung der phospho-organischen ,verbindung und ihre ,rolle bei der ,zymasegrung_/ #dg1 #di1 #ef1 #ajf ,centr4 ,bakt4 ,par41 ,abt4 ,,ii41 #bd1 #a-ab4 ,,iwanoff1 ,,leonid 7#aiji1 #b71 _/,ueber einen neuen ,apparat fr ,grungsversuche_/ #bi ,centr4 ,bakt4 ,par41 ,abt4 ,,ii41 #bd1 #dbi-dcb4 ,,janssens1 ,a41 and ,a4 ,,leblanc 7#ahih71 _/,recherches cytologiques sous la cellule de levure_/ #abf ,la ,cellule1 #ad1 #bjc-bda4 ,,karauschanoff1 ,s4 7#aiaa71 _/,zur ,frage nach der ,bedeutung des ,dioxyacetons als eines intermediren ,produktes der alkoholischen ,grung_/ #aje ,ber4 deutsch1 bot4 ,ges41 #bi1 #cbb4 ,,karczag1 ,l4 7#aiab1 #a71 _/,ueber die ,grung der verschiedenen ,weinsuren_/ #ha ,biochem4 ,zeitsch41 #ch1 #eaf-eah4 ,,karczag1 ,l4 7#aiab1 #b71 _/,in welcher ,weise wird die ,weinsure durch ,hefe angegriffen8_/ #ha ,biochem4 ,zeitsch41 #dc1 #dd-df4 ,,kayser1 ,e4 7#aiaa71 _/,sur le suc de levure de bire_/ #bf ,compt4 rend41 #aeb1 #abgi-abhj4 ,,knoop1 ,f4 7#aiaj71 _/,ueber den physiologischen ,abbau der ,suren und die ,synthese einer ,aminosure im ,tierkorper_/ #ic ,zeitsch4 physiol4 ,chem41 #fg1 #dhg-ejb4 ,,kohl1 ,f4 ,g4 7#aijg71 _/,ueber das ,glykogen und einige ,erscheinungen bei der ,sporulation der ,hefe_/ #aaf ,ber4 deut4 bot4 ,ges41 #be1 #gd-he4 ,,kohl1 ,f4 ,g4 7#aiji71 _/,alkoholische ,grung_/ #aaf ,inaug4 ,diss4 ,leipzig ,abstr4 in ,zeitsch4 ,brauereiwesen1 #cb1 #djf-g1 and ,j4 ,inst4 ,brewing1 #ae1 #gaj-gaa4 ,,kostytscheff1 ,s4 7#aiab1 #a71 _/,bildung von ,acetaldehyd bei der alkoholischen ,zuckergrung_/4 7,vorlufige ,mitteilung7 #aaa ,ber41 #de1 #abhi-abic4 ,,kostytscheff1 ,s4 7#aiab1 #b71 _/,ueber ,alkoholgrung_/4 7#a ,mitteilung47 _/,ueber die ,bildung von ,acetaldehyd bei der alkoholischen ,zuckergrung_/ #ajf1 #aji ,zeitsch4 physiol4 ,chem41 #gi1 #acj-ade4 ,,kostytscheff1 ,s4 7#aiab1 #c71 _/,ueber ,alkoholgrung_/4 7#b ,mitteilung47 _/,ueber die ,bildung von thylalkohol aus ,acetaldehyd durch lebende und gettete ,hefe4 ,von ,s4 ,kostytscheff und ,e4 ,hbbenet_/ #aaj ,zeitsch4 physiol4 ,chem41 #gi1 #cei-cgd4 ,,kostytscheff1 ,s4 7#aiac1 #a71 _/,ueber den ,mechanismus der alkoholischen ,grung_/ #aaa ,ber41 #df1 #cci4 ,,kostytscheff1 ,s4 7#aiac1 #b71 _/,ueber ,alkoholgrung4 ,,iii4 ,die ,bedingungen der ,bildung von ,acetaldehyd bei der ,grung von ,dauerhefe_/ #aaa1 #aac ,zeitsch4 physiol4 ,chem41 #hc1 #ic-aaa4 ,,kostytscheff1 ,s4 7#aiad71 _/,ueber ,alkoholgrung_/ 7#f ,mitteilung7 _/,das ,wesen der reduktion von ,acetaldehyd durch lebenden ,hefe_/ #aaa ,zeitsch4 physiol4 ,chem41 #hi1 #cfg-cgb4 ,,kostytscheff1 ,s41 and ,e4 ,h,,bbenet 7#aiac71 _/,zur ,frage der ,reduktion von ,acetaldehyd durch ,hefesaft_/ #aaj1 #aae ,zeitsch4 physiol4 ,chem41 #he1 #djh-daa4 ,,kostytscheff1 ,s41 and ,w4 ,,brilliant 7#aiac71 _/,ueber ,alkoholgrung4 ,v4 ,ueber ,eiweissspaltung durch ,dauerhefe in ,gegenwart von ,zinkchlorid_/ #aaa ,zeitsch4 physiol4 ,chem41 #he1 #ejg-eaf4 ,,kostytscheff1 ,s41 and ,a4 ,,scheloumoff 7#aiac71 _/,ueber ,alkoholgrung4 ,,iv4 ,ueber ,zuckerspaltung durch ,dauerhefe in ,gegenwart von ,zinkchlorid_/ #aaa1 #aac ,zeitsch4 physiol4 ,chem41 #he1 #dic-ejf4 ,,kunz1 ,r4 7#aijf71 _/,ist die bei der alkoholischen ,hefegrung entstehende ,bernsteinsure als ,spaltungsprodukt des ,zuckers anzusehen8_/ #hi ,zeitsch4 ,unters4 ,nahr4 ,genussmittel1 #ab1 #fda-fde4 ,,kupffer1 ,c4 ,v4 7#ahig7 #ai ,mnchen1 med4 ,wochensch41 #dd1 #cba-cbb4 ,,kusseroff1 ,r4 7#aiaj71 _/,eine neue ,theorie der alkoholischen ,grung_/ #aaf ,centr4 ,bakt4 ,par41 ,abt4 ,,ii41 #bf1 #ahd-ahg4 ,k,,tzing1 ,,friedrich 7#ahcg71 _/,mikroskopische ,untersuchungen ber die ,hefe und ,essigmutter1 nebst mehreren anderen dazugehrigen vegetabilischen ,gebilden_/4 7_/,im ,auszuge vorgetragen in der ,vers4 d4 ,naturhistor4 ,vereins des ,harzes1 in ,alexisbad am #bf ,juli1 #ahcg_/7 #g ,j4 pr4 ,chem41 #aa1 #che-dji4 ,,lange1 ,h4 7#ahih71 _/,beitrag zur alkoholischen ,grung ohne ,hefezellen_/ #ai ,wochensch4 ,brauerei1 #ae1 #cgg-cgh4 ,,lavoisier1 ,a4 7#aghi71 _/,trait lmentaire de ,chymie_/1 ,chap4 ,,xiii #b ,,leathes1 ,j4 ,b4 7#aijf71 _/,problems in ,animal ,metabolism_/ #aaj ,london1 #ha-hf4 ,,lebedeff1 ,,alex4 ,v4 7#aijh71 _/,auftreten von ,formaldehyd bei der zellfreien ,grung_/ #aag ,biochem4 ,zeitsch41 #aj1 #ded-deg4 ,,lebedeff1 ,,alex4 ,v4 7#aiji71 _/,versuche zur ,aufklrung des zellenfreien ,grungsprocesses mit ,hilfe des ,ultrafilters_/ #bi1 #ca1 #dg1 #di1 #ej ,biochem4 ,zeitsch41 #bj1 #aad-abe4 ,,lebedeff1 ,,alex4 ,v4 7#aiaj71 _/,ueber ,hexosephosphorsureester_/4 7#a ,mitteilung7 #ca1 #dg1 #dh1 #ej ,biochem4 ,zeitsch41 #bh1 #bac-bbi4 ,,lebedeff1 ,,alex4 ,v4 7#aiaa1 #a71 _/,ueber den ,mechanismus der alkoholischen ,grung_/ #aje1 #ajf ,ber41 #dd1 #bicb-bidb4 ,,lebedeff1 ,,alex4 ,v4 7#aiaa1 #b71 _/,extraction de la zymase par simple macration_/ #bd ,compt4 rend41 #aeb1 #di-ea4 ,,lebedeff1 ,,alex4 ,v4 7#aiaa1 #c71 _/,sur l'extraction de la zymase_/ #bd ,compt4 rend41 #aeb1 #aabi4 ,,lebedeff1 ,,alex4 ,v4 7#aiaa1 #d71 _/,la zymase est-elle une diastase8_/ #cd1 #ce ,ann4 ,inst4 ,past41 #be1 #fhb-fid4 7,bull4 ,soc4 ,chim41 ,,iv41 #i1 #fgb-fhb47 ,,lebedeff1 ,,alex4 ,v4 7#aiaa1 #e71 _/,bemerkungen zu der ,arbeit von ,hans ,euler und ,sixten ,kullberg4 ,ueber die ,wirkungsweise der ,phosphatese_/ #dg ,zeitsch4 physiol4 ,chem41 #ge1 #dii-ejj4 ,,lebedeff1 ,,alex4 ,v4 7#aiaa1 #f71 _/,ueber ,hexosephos phorsureester4 ,,ii4_/ #dg1 #ej ,biochem4 ,zeitsch41 #cf1 #bdh-bfj4 ,,lebedeff1 ,,alex4 ,v4 7#aiaa1 #g71 _/,sur l'extraction de la zymase_/ #bd ,bull4 ,soc4 ,chim41 ,,iv41 #i1 #gdd-gej4 ,,lebedeff1 ,,alex4 ,v4 7#aiab1 #a71 _/,ueber die ,extraktion der ,zymase_/ #bd ,chem4 ,zeit41 #cf1 #cfe4 ,,lebedeff1 ,,alex4 ,v4 7#aiab1 #b71 _/,extraction de la ,zymase par simple macration_/ #bd ,ann4 ,inst4 ,past41 #bf1 #h-cg4 ,,lebedeff1 ,,alex4 ,v4 7#aiab1 #c71 _/,notiz ber ,phosphatese_/ #dg ,biochem4 ,zeitsch41 #ci1 #aee-aeg4 ,,lebedeff1 ,,alex4 ,v4 7#aiab1 #d71 _/,ueber den ,mechanismus der alkoholischen ,grung4_/ #ajg ,biochem4 ,zeitsch41 #df1 #dhc-dhi 7and ,bull4 ,soc4 ,chim41 ,,iv41 #aa1 #ajci-ajda74 ,,lebedeff1 ,,alex4 ,v4 7#aiac1 #a71 _/,ueber die ,veresterung von ,dioxyaceton mit ,phosphaten_/ #dg ,zeitsch4 physiol4 ,chem41 #hd1 #cje4 ,,lebedeff1 ,,alex4 ,v4 7#aiac1 #b71 _/,ueber den kinetischen ,verlauf der alkoholischen ,grung_/ #ca ,zeitsch4 ,grungsphysiol41 #b1 #ajd-ajf4 ,,lebedeff1 ,,alex4 ,v4 7#aiad1 #a71 _/,ueber den ,mechanismus der alkoholischen ,grung ,,iii4 ,zellenfreie ,grung der ,polyoxy-carbonsuren_/ #ajh ,ber41 #aiad1 #dg1 #ffj-fgb4 ,,lebedeff1 ,,alex4 ,v4 7#aiad1 #b71 _/,notij ber zellenfreie ,grung der ,poly-oxycarbonsuren_/ #ajh ,ber41 #aiad1 #dg1 #ife-ifg4 ,,lebedeff1 ,,alex4 ,v41 and ,n4 ,,griaznoff 7#aiab71 _/,ueber den ,mechanismus der alkoholischen ,grung_/ #ajg1 #aaj ,ber41 #de1 #cbef-cbgb4 ,,liebig1 ,,justus ,v4 7#ahci71 _/,ueber die ,erscheinungen der ,grung1 ,fulnis und ,verwesung und ihre ,ursachen_/ #h ,annalen1 #cj1 #bej-bhg4 ,,liebig1 ,,justus ,v4 7#ahgj71 _/,ueber die ,grung und die ,quelle der ,muskelkraft_/ #ac ,annalen1 #aec1 #a-dg2 #acg-bbh4 ,,lindner1 ,,paul 7#aije71 _/,mikroskopische ,betriebskontrolle in den ,grungsgewerben_/ #aca ,berlin1 #dth edition1 #bcd4 ,,lintner1 ,c4 ,j4 7#ahii7 #ai ,chem4 ,zeit1 #bc1 #hea4 ,,lintner1 ,c4 ,j41 and ,h4 ,j4 ,v4 ,,liebig 7#aiaa71 _/,ueber die ,reduktion des ,furfurols durch ,hefe bei der alkoholischen ,grung_/ #aac ,zeitsch4 physiol4 ,chem41 #gb1 #ddi-ded4 ,,lintner1 ,c4 ,j41 and ,h4 ,l,,ers 7#aiac71 _/,ueber die ,reduktion des ,chloralhydrates durch ,hefe bei der alkoholischen ,grung_/ #aac ,zeitsch4 physiol4 ,chem41 #hh1 #abb-abc4 ,,lippmann1 ,e4 ,v4 7#aijd71 _/,die ,chemie der ,zuckerarten_/ #ig1 #ajj1 #acb ,braunschweig4 ,l,b1 ,,walter 7#aijf71 _/,zur chemischen ,theorie der alkoholischen ,grung_/ #aaf1 #aag ,landwirtsch4 ,jahrb41 #ce1 #eda2 ,chem4 ,zeit41 #db1 #edj2 ,zeitsch4 ,elektrochem41 #aijf1 #ab1 #bhb2 #aijg1 #ac1 #caa-eaf4 ,l,b1 ,,walter 7#aijh1 #a71 _/,zur ,kenntnis der ,zuckerspaltungen_/4 ,i4 ,mitteilung4 _/,die ,einwirkung von ,zinkcarbonat auf ,formaldehydlsungen_/ #aag ,biochem4 ,zeitsch41 #ab1 #gh-if4 ,l,b1 ,,walter 7#aijh1 #b71 _/,zur ,kenntnis der ,zuckerspaltungen_/4 ,,ii4 ,mitteilung4 _/,die ,einwirkung von ,zinkstaub und ,eisen auf ,formaldehydlsungen2 die ,einwirkung von ,zinkstaub auf ,traubenzucker_/ #aag ,biochem4 ,zeitsch41 #ab1 #dff-dgb4 ,l,b1 ,,walter 7#aiji1 #a71 _/,zur ,kenntnis der ,zuckerspaltungen_/4 ,,iii4 ,mitteilung4 _/,die ,elektrolyse des ,traubenzuckers_/ #aag ,biochem4 ,zeitsch41 #ag1 #acb-add4 ,l,b1 ,,walter 7#aiji1 #b71 _/,zur ,kenntnis der ,zuckerspaltungen_/4 ,v4 7,vorlufige7 ,mitteilung4 _/,die ,umkehrung der ,zuckersynthese_/ #aag ,biochem4 ,zeitsch41 #bj1 #eaf-ebb4 ,l,b1 ,,walter 7#aiji1 #c71 _/,zur ,kenntnis der ,zuckerspaltungen_/4 ,,vi4 ,mitteilung4 _/,die elektrolytische ,reduktion des ,traubenzuckers_/ #aag ,biochem4 ,zeitsch41 #bb1 #ajc-aje4 ,l,b1 ,,walter 7#aiji1 #d71 _/,zur ,kenntnis der ,zuckerspaltungen_/4 ,,vii4 ,mitteilung4 _/,die ,umkehrung der ,zuckersynthese 7von ,walter ,lb und ,georg ,pulvermacher7_/ #aag ,biochem4 ,zeitsch41 #bc1 #aj-bf4 ,l,b1 ,,walter 7#aiaj71 _/,zur geschichte der chemischen ,grungshypothesen_/ #ajg ,biochem4 ,zeitsch41 #bi1 #caa-cae4 ,l,b1 ,,walter1 und ,,georg ,,pulvermacher 7#aiji71 _/,zur ,kenntnis der ,zuckerspaltung_/4 ,,iv4 ,mitteilung4 _/,die ,elektrolyse des glycerins und des ,glykols_/ #aag ,biochem4 ,zeitsch41 #ag1 #cdc-cee4 ,,lowry1 ,t4 ,,martin 7#aijc71 _/,studies of dynamic isomerism4 ,i4 ,the mutarotation of glucose_/ #acc ,j4 ,chem4 ,soc1 #hc1 #acad-acbc4 ,l,,dersdorff1 ,f4 ,v4 7#ahdf71 _/,ueber die ,natur der ,hefe_/ #ae ,ann4 ,physik41 #gf1 #djh-daa4 ,,lunge1 ,g4 7#aije71 _/,chemisch-technische ,untersuchungsmethoden_/ #hg 7,berlin1 #ete ,aufgabe71 #c1 #ega4 ,,luther 7#aijg7 #ajc ,zeitsch4 ,elektrochem41 #ac1 #eag4 ,,lvoff1 ,,sergius 7#aiac1 #a71 _/,zymase und ,reduktase in ihren gegenseitigen ,beziehungen_/ #aab ,ber4 deut4 bot4 ,ges41 #ca1 #ada-adg4 ,,lvoff1 ,,sergius 7#aiac1 #b71 _/,sur le rle de la reductase dans la fermentation alcoolique_/ #aab ,bull4 ,acad4 ,sci4 ,st4 ,ptersbourg1 #eja-ecb4 ,,lvoff1 ,,sergius 7#aiac1 #c71 _/,hefegrung und ,wasserstoff_/ #aab ,zeitsch4 ,grungsphysiol41 #c1 #bhi-cbj4 ,,macfadyen1 ,,allan1 ,g4 ,,harris ,,morris1 and ,,sydney ,,rowland 7#aijj71 _/,ueber ausgepresstes ,hefezellplasma_/ 7_/,buchner's ,zymase_/7 #ai1 #bd1 #bg1 #cj ,ber41 #cc1 #bgfd-bgij4 ,,mckenzie1 ,,alex41 and ,,arthur ,,harden 7#aijc71 _/,the biological method for resolving inactive acids into their optically active components_/ #hi ,j4 ,chem4 ,soc1 #hc1 #dbd-dch4 ,,magnus-,,levy1 ,a4 7#aijb71 _/,ueber den ,aufbau der hohen ,fettsuren aus ,zucker_/ #aaj ,arch4 ,anat4 ,physiol41 #cfe-cfh4 ,,manasse,n1 ,,marie ,v4 7#ahgb71 _/,mikroskopische ,untersuchungen4 ,herausgegeben von ,wiesner_/ #ae ,stuttgart1 #abh4 ,,manasse,n1 ,,marie ,v4 7#ahig71 _/,zur ,frage von der alkoholischen ,grung ohne lebende ,hefezellen_/ #ae ,ber41 #cj1 #cjfa-cjfb4 ,,marckwald1 ,w4 7#aijb71 _/,ueber die ,trennung der ,amylalkohole des ,fuselles4 ,,iii4_/ #hh ,ber41 #ce1 #aeie-afja4 ,,martin1 ,c4 ,j4 7#ahif71 _/,a rapid method of separating colloids from crystalloids in solutions containing both_/ #ei ,j4 ,physiol41 #bj1 #cfd-cga4 ,,martin1 ,c4 ,j41 and ,h4 ,g4 ,,chapman 7#ahih71 _/,an endeavour to procure an alcoholic ferment from yeast-cells_/ #ai ,proc4 physiol4 ,soc41 #aa ,june1 ii4 ,,mayer1 ,,adolf 7#ahgi71 _/,lehrbuch der ,grungschemie #c4 ,ausgabe_/ #ae ,heidelberg1 ,carl ,winters' ,univ4-buchh4 ,,mayer1 ,p4 7#aijg71 _/,zur ,frage der ,vergrbarkeit von ,methylglyoxal_/ #ajd ,biochem4 ,zeitsch41 #b1 #dce-dcg4 ,,maz1 ,p4 7#aijb71 _/,recherches sur les modes d'utilisaion du carbone trnaire par les vgtaux et les microbes_/ #ih ,ann4 ,inst4 ,pasteur1 #af1 #ddf2 ,compt4 rend41 #acd1 #bda4 ,,meisenheimer1 ,,jakob 7#aijc71 _/,neue ,versuche mit ,hefepresssaft_/ #ce ,zeitsch4 physiol4 ,chem41 #cg1 #eah-ebf4 ,,meisenheimer1 ,,jakob 7#aijg71 _/,ueber die chemischen ,vorgnge bei den als ,enzymreaktionen erkannten ,grungen_/ #ajj ,biochem4 ,centr41 #f1 #a-ac4 ,,meisenheimer1 ,,jakob 7#aijh71 _/,ueber das ,verhalten der ,glukose1 ,fructose und ,galaktose gegen verdnnte ,natronlauge_/ #ig ,ber41 #da1 #ajji-ajai4 ,,mitscherlich1 ,,eilhard 7#ahda71 _/,ueber die chemische ,zersetzung und ,verbindung mittels ,contactsubstanzen_/ #aj ,monatsber4 ,k4 ,akad4 d4 ,wissensch4 ,berlin1 #ahda1 #cib2 ,ann4 ,physik41 #ahdb1 #ee1 #bji-bbi4 ,n,,geli1 ,c4 ,v4 7#ahgi71 _/,theorie der ,grung_/ #ae ,mnchen4 ,r4 ,oldenbourg1 #aef4 ,n,,geli1 ,c41 und ,o4 ,,loew 7#ahgh71 _/,ueber die chemische ,zusammensetzung der ,hefe_/ #ae ,annalen1 #aic1 #cbb-cdh4 ,,nef1 ,j4 ,u4 7#aijd71 _/,dissoziationsvorgnge in der ,glycolglycerinreihe_/ #ih ,annalen1 #cce1 #bdg-ccc4 ,,nef1 ,j4 ,u4 7#aijg71 _/,dissoziationsvorgnge in der ,zuckergruppe_/4 7,i4 ,abhandlung47 _/,ueber das ,verhalten der ,zuckerarten gegen die ,fehling'sche ,lsung sowie gegen andere ,oxydationsmittel_/ #ih ,annalen1 #ceg1 #bad-cab4 ,,neisser1 ,m4 7#aijf71 _/,ein ,fall von ,mutation nach de ,vries bei ,bakterien und andere ,demonstrationen_/ #acb ,cent4 ,bakt4 ,par41 ,abt4 ,i41 ,ref4 #ch1 ,append41 #ih-ajb4 ,,neubauer1 ,,otto and ,,konrad ,,fromherz 7#aiaa71 _/,ueber den ,abbau der ,aminosuren bei der ,hefegrung_/ #ib1 #aji ,zeitsch4 physiol4 ,chem41 #gj1 #cbf-cej4 ,,neuberg1 ,,carl 7#aijh71 _/,chemische ,umwandlungen durch ,strahlenarten_/4 ,i4 ,mitteilung4 _/,katalytische ,reaktionen des ,sonnenlichtes_/ #ic ,biochem4 ,zeitsch41 #ac1 #cje-cbj4 ,,neuberg1 ,,carl 7#aiji71 _/,chemische ,umwandlungen durch ,strahlenarten_/4 ,,ii4 ,mitteilung4 _/,wirkungen des elektrischen ,gleichstroms_/ #ic ,biochem4 ,zeitsch41 #ag1 #bgj-bib4 ,,neuberg1 ,,carl 7#aiab71 _/,ueber zuckerfreie ,hefegrungen1 ,,vii4 ,bildung von -,oxybuttersurealdehyd 7,aldol7 bei der ,vergrung von ,brenztraubensure_/ #hb ,biochem4 ,zeitsch41 #dc1 #dia-dic4 ,,neuberg1 ,,carl1 and ,a4 ,,hildesheimer 7#aiaa71 _/,ueber zuckerfreie ,hefegrungen1 ,i4_/ #ha ,biochem4 ,zeitsch41 #ca1 #agj-agf4 ,,neuberg1 ,,carl1 and ,l4 ,,karczag 7#aiaa1 #a71 _/,die ,grung der ,brenztraubensure und ,oxalessigsure als ,vorlesungsversuch_/ #ha ,ber41 #dd1 #bdgg-bdgi4 ,,neuberg1 ,,carl1 and ,l4 ,,karczag 7#aiaa1 #b71 _/,ueber zuckerfreie ,hefegrungen1 ,,iii4_/ #hb1 #abg ,biochem4 ,zeitsch41 #cf1 #fj-fg4 ,,neuberg1 ,,carl1 and ,l4 ,,karczag 7#aiaa1 #c71 _/,ueber zuckerfreie ,hefegrungen1 ,,iv4 ,carboxylase ein neues ,enzym der ,hefe_/ #hb ,biochem4 ,zeitsch41 #cf1 #fh-ge4 ,,neuberg1 ,,carl1 and ,l4 ,,karczag 7#aiaa1 #d71 _/,ueber zuckerfreie ,hefegrungen1 ,v4 ,zur ,kenntnis der ,carboxylase_/ #ha1 #hc ,biochem4 ,zeitsch41 #cf1 #gf-ha4 ,,neuberg1 ,,carl1 and ,l4 ,,karczag 7#aiaa1 #e71 _/,ueber zuckerfreie ,hefegrungen1 ,,vi4_/ #hb ,biochem4 ,zeitsch41 #cg1 #agj-agf4 ,,neuberg1 ,,carl1 and ,,johannes ,,kerb 7#aiab1 #a71 _/,ueber zuckerfreie ,hefegrungen1 ,,viii4 ,enstehung von ,acetaldehyd bei der sog4 ,selbstgrung_/ #aaa1 #aab ,biochem4 ,zeitsch41 #dc1 #did-dii4 ,,neuberg1 ,,carl1 and ,,johannes ,,kerb 7#aiab1 #b71 _/,ueber zuckerfreie ,hefegrungen1 ,,ix4 ,vergrung von ,ketosuren durch ,weinhefen_/ #ha ,biochem4 ,zeitsch41 #dg1 #dje-dab4 ,,neuberg1 ,,carl1 and ,,johannes ,,kerb 7#aiab1 #c71 _/,ueber zuckerfreie ,hefegrungen1 ,x4 ,die ,grung der -,ketobuttersure_/ #hb ,biochem4 ,zeitsch41 #dg1 #dac-dbj4 ,,neuberg1 ,,carl1 and ,,johannes ,,kerb 7#aiab1 #d71 _/,entsteht bei zuckerfreien ,hefegrungen thylalkohol8_/ #aji1 #aaj1 #aae ,zeitsch4 ,grungphysiol41 #a1 #aad-abj4 ,,neuberg1 ,,carl1 and ,,johannes ,,kerb 7#aiac1 #a71 _/,ueber zuckerfreie ,hefegrungen1 ,,xii4 ,ueber die ,vorgnge bei der ,hefegrung_/ #hb1 #ic1 #aaj ,biochem4 ,zeitsch41 #ec1 #djf-dai2 ,ber41 #df1 #bbbe-bbbh4 ,,neuberg1 ,,carl1 and ,,johannes ,,kerb 7#aiac1 #b71 _/,ueber zuckerfreie ,hefegrungen1 ,,xiii4 ,zur ,frage der ,aldehydbildung bei der ,grung von ,hexosen sowie bei der sog4 ,selbstgrung_/ #aab1 #aac ,biochem4 ,zeitsch41 #eh1 #aeh-agj4 ,,neuberg1 ,,carl1 and ,w4 ,,oertel 7#aiac71 _/,studien ber ,methylglyoxalbildung_/ #ii ,biochem4 ,zeitsch41 #ee1 #die-ejc4 ,,neuberg1 ,,carl1 and ,p4 ,,rosenthal 7#aiac71 _/,ueber zuckerfreie ,hefegrungen1 ,,xi4 ,weiteres zur ,kenntnis der ,carboxylase_/ #df1 #hb1 #hc1 #ic ,biochem4 ,zeitsch41 #ea1 #abh-adb4 ,,neuberg1 ,,carl1 and ,h4 ,,steenbock 7#aiac71 _/,ueber die ,bildung hherer ,alkohole aus ,aldehyden durch ,hefe1 ,i4 ,uebergang von ,valeraldehyd in ,amyl ,alkohol_/ #ic1 #aac ,biochem4 ,zeitsch41 #eb1 #did-ejc4 ,,neuberg1 ,,carl1 and ,h4 ,,steenbock 7#aiad71 _/,ueber die ,bildung hherer ,alkohole aus ,aldehyden durch ,hefe1 ,,ii4_/ #ic1 #aac ,biochem4 ,zeitsch41 #ei1 #ahh-aib4 ,,neuberg1 ,,carl1 and ,l4 ,,tir 7#aiaa71 _/,ueber zuckerfreie ,hefegrungen1 ,,ii4_/ #ha ,biochem4 ,zeitsch41 #cb1 #cbc-cca4 ,,neumeister1 ,r4 7#ahig71 _/,bemerkungen zu ,eduard ,buchner's ,mitteilungen ber ,zymase_/ #ai ,ber41 #cj1 #bifc-biff4 ,,oppenheimer1 ,,max 7#aiad1 #a71 _/,ueber die ,bildung von ,milchsure bei der alkoholischen ,grung_/ #ajb1 #aji ,zeitsch4 physiol4 ,chem41 #hi1 #de-fb4 ,,oppenheimer1 ,,max 7#aiad1 #b71 _/,ueber die ,bildung von ,glycerin bei der alkoholischen ,grung_/ #cc1 #ie1 #ajb1 #aji ,zeitsch4 physiol4 ,chem41 #hi1 #fc-gg4 ,o',,sullivan1 ,,james 7#ahih71 _/,on the rate of alcoholic fermentation_/ #abh ,j4 ,soc4 ,chem4 ,ind41 #ag1 #eei-efj4 ,o',,sullivan1 ,,james 7#ahii71 _/,the hydrolytic and fermentative functions of yeast_/ #abh ,j4 ,inst4 ,brewing 7#c71 #e1 #afa-age4 ,,parnas1 ,,jakob 7#aiaj71 _/,ueber fermentative ,beschleunigung der ,cannizzaroschen ,aldehydumlagerung durch ,gewebesfte_/ #id ,biochem4 ,zeitsch41 #bh1 #bgd-bid4 ,,paine1 ,,sydney1 ,g4 7#aiaa71 _/,the permeability of the yeast cell_/ #ea ,proc4 ,roy4 ,soc11 ,b41 #hd1 #bhi-cjg4 ,,palladin1 ,w4 7#aijh71 _/,beteiligung der ,reduktase im ,prozesse der ,alkoholgrung_/ #aaa ,zeitsch4 physiol4 ,chem41 #ef1 #ha-hh4 ,,pasteur1 ,,louis 7#aheg71 _/,mmoire sur la fermentation appele lactique_/ #aa ,compt4 rend41 #de1 #iac-iaf4 ,,pasteur1 ,,louis 7#ahfj71 _/,mmoire sur la fermentation alcoolique_/ #aa1 #ab ,ann4 ,chim4 ,phys41 7#c71 #eh1 #cbc-dbf4 ,,pasteur1 ,,louis 7#ahgb71 _/,note sur la mmoire de ,m4 ,liebig relatif aux fermentations_/ #ac ,ann4 ,chim4 ,phys41 7#d71 #be1 #ade-aea4 ,,pasteur1 ,,louis 7#ahge71 _/,nouvelles observations sur la nature de la fermentation alcoolique_/ #ac1 #ad ,compt4 rend41 #hj1 #deb-deg4 ,,pavy1 ,f4 ,w41 and ,h4 ,w4 ,,bywaters 7#aijg71 _/,on glycogen formation by yeast_/ #aaf ,j4 ,physiol41 #cf1 #adi-afc4 ,,payen1 ,,anselme et ,,persoz 7#ahcc71 _/,mmoire sur la diastase1 les principaux produits de ses reactions et leur applications aux arts industriels_/ #ad ,ann4 ,chim4 ,phys41 #ec1 #gc-ib4 ,,piloty1 ,,oscar 7#ahig71 _/,ueber eine neue ,totalsynthese des glycerins and des ,dioxyacetons_/ #ajd ,ber41 #cj1 #cafa-cafi4 ,,pinkus1 ,,georg 7#ahih71 _/,ueber die ,einwirkung von ,benzhydrazid auf ,glukose_/ #ih ,ber41 #ca1 #ca-cg4 ,,plimmer1 ,,robert ,,henry ,,aders 7#aiac71 _/,the metabolism of organic phosphorus compounds4 ,their hydrolysis by the action of enzymes_/ #ea ,biochem4 ,j41 #g1 #dc-ga4 ,,pringsheim1 ,,hans ,h4 7#aije71 _/,zur ,fusellfrage_/ #hf ,ber41 #ch1 #dhf-dhg4 ,,pringsheim1 ,,hans ,h4 7#aijf71 _/,ueber die ,bildung von ,fusell bei ,acetondauerhefe-,grung_/ #hg ,ber41 #ci1 #cgac-cgae4 ,,pringsheim1 ,,hans ,h4 7#aijg71 _/,ueber die ,stickstoffernhrung der ,hefe4 7,ein ,beitrag zur ,physiologie der ,hefe7_/ #hf ,biochem4 ,zeitsch41 #c1 #aba-bhf4 ,,pringsheim1 ,,hans ,h4 7#aijh71 _/,ueber die ,unterdrckung der ,fusellbildung und die ,mitwirkung von ,bakterien an der ,bildung hherer ,alkohole bei der ,grung_/ #hf ,biochem4 ,zeitsch41 #aj1 #dij-dig4 ,,pringsheim1 ,,hans ,h4 7#aiji71 _/,bemerkungen zur ,mitwirkung von ,bakterien an der ,fusellbildung_/ #hf ,biochem4 ,zeitsch41 #af1 #bdc-bde4 ,,resenscheck1 ,,friederich 7#aijh1 #a71 _/,einwirkung des elektrischen ,stromes auf den ,hefepresssaft_/ #fg ,biochem4 ,zeitsch41 #i1 #bee-bfc4 ,,resenscheck1 ,,friederich 7#aijh1 #b71 _/,einwirkung von kolloidalem ,eisenhydroxyd auf den ,hefepresssaft_/ #fg ,biochem4 ,zeitsch41 #ae1 #a-aa4 ,,rinckleben1 ,p4 7#aiaa71 _/,gewinnung von ,zymase aus frischer ,brauereihefe durch ,plasmolyse_/ #bf ,chem4 ,zeit41 #ce1 #aadi-aaej4 ,,rowland1 ,,sydney 7#aija71 _/,a method of obtaining intracellular juices_/ #bd ,j4 ,physiol41 #bg1 #ec-ef4 ,,rubner1 ,,max 7#aiac71 _/,die ,ernhrungsphysiologie der ,hefezelle bei alkoholischer ,grung_/ #abf ,rubner's ,archiv4 ,physiologie ,suppl4 ,bd41 #a-cfi4 ,,salkowski1 ,e4 und ,h4 7#ahgi71 _/,weitere ,beitrge zur ,kenntnis der ,fulnisprodukte des ,eiweiss_/ #ij ,ber41 #ab1 #fdh-fee4 ,,schade1 ,h4 7#aijf71 _/,ueber die ,vergrung des ,zuckers ohne ,enzyme_/ #aad ,zeitsch4 physikal4 ,chem41 #eg1 #a-df4 ,,schade41 ,h4 7#aijg71 _/,berichtigung und ,nachtrag zu der ,arbeit ,ueber die ,vergrung des ,zuckers ohne ,fermente_/ #aad ,zeitsch4 physikal4 ,chem41 #fj1 #eaj-eab4 ,,schade1 ,h4 7#aijh71 _/,ueber die ,vorgnge der ,grung vom ,standpunkt der ,katalyse_/ #aad ,biochem4 ,zeitsch41 #g1 #bii-cbf4 ,,schlossberger1 ,j4 7#ahdd71 _/,ueber die ,natur der ,hefe1 mit ,rcksicht auf die ,grungserscheinungen_/ #aj ,annalen1 #ea1 #aic-bab4 ,,schmidt1 ,c4 7#ahdg71 _/,grungsversuche_/ #ae ,annalen1 #fa1 #afh-agd4 ,,schroeder1 ,h4 7#ahei1 #ahfa71 _/,ueber ,filtration der ,luft in ,beziehung auf ,fulnis und ,grung_/ #aj ,annalen1 #aji1 #ce-eb2 #aag1 #bgc-bie4 ,,schroeder1 ,h41 und ,,th4 ,v4 ,,dusch 7#ahed71 _/,ueber ,filtration der ,luft in ,beziehung auf ,fulnis und ,grung_/ #aj ,annalen1 #hi1 #bcb-cdc4 ,,schrohe1 ,a4 7#aijd71 _/,eilhard ,mitscherlich und die vitalistische ,grungstheorie in der deutschen ,literatur vor ,pasteur_/ #i1 #aa ,hefe1 ,grung und ,fulnis1 #bjh-bbi ,parey1 ,berlin4 ,,schulze1 ,,franz 7#ahcf71 _/,vorlufige ,mitteilung der ,resultate einer experimentellen ,beobachtung ber ,generatio aequivoca_/ #f ,ann4 ,physik41 #ci1 #dhg-dhi4 ,,schwann1 ,,theodor 7#ahcg71 _/,vorlufige ,mitteilung1 betreffend ,versuche ber die ,weingrung und ,fulnis_/ #f ,ann4 ,physik41 #da1 #ahd-aic4 ,,slator1 ,,arthur 7#aijf71 _/,studies in fermentation_/4 ,part ,i4 _/,the chemical dynamics of alcoholic fermentation by yeast_/ #bi1 #ajc1 #abh ,j4 ,chem4 ,soc41 #hi1 #abh-adb4 ,,slator1 ,,arthur 7#aijg71 _/,ueber ,zwischenprodukte der alkoholischen ,grung_/ #ajc ,ber41 #dj1 #abc-abf4 ,,slator1 ,,arthur 7#aijh1 #a71 _/,studies in ,fermentation_/4 ,part ,,ii4 _/,the mechanism of alcoholic fermentation_/ #ajc1 #acj1 #aca1 #acb1 #acc1 #acd ,j4 ,chem4 ,soc41 #ic1 #bag-bdb4 ,,slator1 ,,arthur 7#aijh1 #b71 _/,factors which influence fermentation_/ #ajc ,chem4 ,news1 #ih1 #age1 and ,brit4 ,ass4 ,reports1 #aijh4 ,,slator1 ,,arthur 7#aiab71 _/,ueber ,dioxyaceton als zwischenstufe der alkoholischen ,grung_/ #ajf ,ber41 #de1 #dc-df4 ,,slator1 ,,arthur1 and ,h4 ,j4 ,s4 ,,sand 7#aiaj71 _/,studies in fermentation_/4 ,part ,,iii4 _/,the rle of diffusion in fermentation by yeast-cells_/ #abi ,j4 ,chem4 ,soc1 #ibb-ibg4 ,,stahl1 ,,georg ,,ernst 7#afig71 _/,zymotechnia fundamentalis_/ #b 7,franckfurth1 #agcd71 #cjd4 ,,stavenhagen1 ,a4 7#ahig71 _/,zur ,kenntnis der ,grungserscheinungen_/ #ai ,ber41 #cj1 #bdbb-bdbc and #bifc4 ,,tafel1 ,,julius 7#aijg71 _/,ueber ,zwischenprodukte bei chemischen ,reaktionen_/ #ajc ,ber41 #dj1 #ccah-ccba4 ,,tammann1 ,g4 7#ahhi71 _/,ueber die ,wirkung der ,fermente_/ #abh ,zeitsch4 physikal4 ,chem41 #c1 #be-cg4 ,,thenard1 ,,louis ,,jacques 7#ahjc71 _/,mmoire sur la fermentation vineuse_/ #d ,ann4 ,chim4 ,phys41 #df1 #bid-cbj4 ,,traube1 ,,moritz 7#aheh71 _/,theorie der ,fermentwirkungen_/ #ad ,berlin1 ,ferd4 ,dummler's ,verlagsbuchh41 #aai4 ,,traube1 ,,moritz 7#ahgg71 _/,die chemische ,theorie der ,fermentwirkungen und der ,chemismus der ,respiration4 ,antwort auf die ,ausserungen des ,herrn ,hoppe-,seyler_/ #ad ,ber41 #aj1 #aihd-aiib4 ,,trommsdorff1 ,,richard 7#aijb71 _/,ueber die ,beziehungen der ,gram'schen ,frbung zu chemischen ,vorgngen in der abgetteten ,hefezelle_/ #ci ,centr4 ,bakt4 ,par41 ,abt4 ,,ii41 #h1 #hb4 ,,turpin 7#ahch71 _/,mmoire sur la cause et les effets de la fermentation alcoolique et acteuse_/ #h ,compt4 rend41 #g1 #cfi-djb4 ,,voit1 ,,carl ,v4 7#ahig7 #ai ,mnchen1 med4 ,wochensch41 #dd1 #cba4 ,,volhard1 ,,jakob 7#aiji71 _/,justus von ,liebig_/ #ac ,johann ,ambrosius ,barth4 ,leipzig4 ,,wager1 ,,harold 7#ahih71 _/,the nucleus of the yeast plant_/ #abf ,annals of ,botany1 #ab1 #ddi4 ,,wager1 ,,harold 7#aiaa71 _/,the yeast cell_/ #abf ,j4 ,inst4 ,brewing1 #b-bb4 ,,wager1 ,,harold1 and ,,annie ,,peniston 7#aiaj71 _/,cytological observations on the yeast plant_/ #aaf1 #abf ,annals of ,botany1 #bd1 #de-hc4 ,,walton1 ,,james ,,henri1 ,jr4 7#aijd71 _/,die ,jodionenkatalyse des ,wasserstoffsuperoxyds_/ #bi ,zeitsch4 physikal4 ,chem41 #dg1 #ahe-bbb4 ,,wehmer1 ,c4 7#ahih7 #ai ,botan4 ,zeit41 #ec4 ,,will1 ,h4 7#ahig71 _/,alkoholische ,grung ohne ,hefezellen_/ #ai ,zeitsch4 ges4 ,brauwesen41 #bj1 #cfc-cfd4 ,,will1 ,h4 7#ahih71 _/,zur ,frage der alkoholischen ,grung ohne ,hefezellen_/ #ai ,zeitsch4 ges4 ,brauwesen41 #ba1 #bia4 ,,windaus1 ,a41 und ,f4 ,,knoop 7#aije71 _/,ueberfhrung von ,traubenzucker in ,methylimidazol_/ #ii ,ber41 #ch1 #aaff-aagj4 ,,wohl1 ,a4 7#aihi71 _/,ueber die ,acetale des ,akrolens und des ,glycerinaldehyds_/ #ajd ,ber41 #ca1 #agif-ahja4 ,,wohl1 ,a4 7#aijg1 #a71 _/,ueber ,oxyfumar- und ,oxymalensure_/ #ajc ,ber41 #dj1 #bbhb-bcjj4 ,,wohl1 ,a4 7#aijg1 #b71 _/,die neueren ,ansichten ber den chemischen ,verlauf der ,grung_/ #ajj1 #ajd ,biochem4 ,zeitsch41 #e1 #de-fe1 and ,zeitsch4 angew4 ,chem41 #bj1 #aafi-aagg4 ,,wohl1 ,a4 7#aijh71 _/,zur ,kenntnis der ,dreikohlenstoffreihe_/ #ih ,ber41 #da1 #ceii-cfab4 ,,wohl1 ,a41 und ,c4 ,,oesterlin 7#aija71 _/,ueberfhrung der ,weinsure in ,oxalessigsure durch ,wasserabspaltung bei niederer ,temperatur_/ #ajj ,ber41 #cd1 #aaci-aadh4 ,w,,hler 7#ahci71 _/,das entrtselte ,geheimniss der geistigen ,grung_/4 7_/,vorlufige briefliche ,mitteilung4_/7 #h ,annalen1 #bi1 #ajj-ajd4 ,,wroblewski1 ,a4 7#ahih71 _/,grung ohne ,hefezellen_/ #ai ,ber41 #ca1 #cbah-cbbe2 ,centr4 ,physiol41 #ab1 #fig-gja4 ,,wroblewski1 ,a4 7#ahii71 _/,ueber den ,buchner'schen ,hefepresssaft_/ #ai ,centr4 ,physiol41 #ac1 #bhd-big4 ,,wroblewski1 ,a4 7#aija71 _/,ueber den ,buchner'schen ,hefepresssaft_/ #ai1 #db ,j4 pr4 ,chem41 7#b71 #fd1 #a-gj4 ,,young1 ,w4 ,j4 7#aiji71 _/,the hexosephosphate formed by yeast-juice from hexose and phosphate_/ #dg1 #ef 7,prel4 ,note1 ,proc4 ,chem4 ,soc41 #aijg1 #fe47 ,proc4 ,roy4 ,soc41 ,b41 #ha1 #ebh-ede4 ,,young1 ,w4 ,j4 7#aiaa71 _/,ueber die ,zusammensetzung der durch ,hefepresssaft gebildeten ,hexosephosphorsure ,,ii4_/ #dg1 #ej ,biochem4 ,zeitsch41 #cb1 #agh-ahh4 ,,index4 ,,acetaldehyde1 as an intermediate product of alcoholic fermentation1 #aaj4 -- reduction of by yeast1 #aaj4 ,acetone-yeast1 #ch4 ,alanine1 as an intermediate product of alcoholic fermentation1 #aae4 ,alcohol1 formation of1 from sugar by alkalis1 #ig4 ,alcoholic fermentation1 attempts to separate enzymes of1 from yeast-cell1 #ae4 -- -- by-products of1 #he4 -- -- equation of1 #ea4 -- -- ,gay-,lussac's theory of1 #d4 -- -- ,iwanoff's theory of1 #ajf4 -- -- kinetics of1 #abj1 #abh4 -- -- ,lavoisier's views on1 #c4 -- -- ,liebig's theory of1 #h4 -- -- ,ngeli's theory of1 #ae4 -- -- of the amino-acids1 #hg4 -- -- -- -- theory of1 #ia4 -- -- ,pasteur's researches on1 #aa4 -- -- ,traube's enzyme theory of1 #ad4 ,alkalis1 effect of1 on hexoses1 #if4 ,amino-acids1 alcoholic fermentation of1 #hg4 -- stereoisomerides of1 fermented at different rates by yeast1 #hi4 d-,amyl alcohol1 formation of from isoleucine1 #hf4 ,antiprotease in yeast-juice1 #db1 #fe4 ,antiseptics1 action of1 on yeast-juice1 #ai1 #cf4 ,arsenate1 effect of1 on fermentation by yeast-juice and zymin1 #gc4 -- -- on autofermentation of yeast-juice1 #hj4 -- nature of acceleration produced by1 #gh4 ,arsenite1 effect of1 on fermentation by yeast-juice1 #gg4 -- -- on autofermentation of yeast-juice1 #hj4 -- nature of acceleration produced by1 #gh4 ,autofermentation of yeast-juice1 #cc1 #aai4 -- -- effect of arsenates and arsenites on1 #hj4 ,,baeyer',s theory of fermentation1 #ii4 ,boiled yeast-juice1 effect of1 on fermentation by yeast-juice1 #da4 ,,carboxylase1 #ha1 #ic4 -- relation of to alcoholic fermentation1 #hc4 ,co-enzyme1 effect of electric current on1 #fg4 -- enzymic destruction of1 #fc4 -- of yeast-juice1 #ei4 -- precipitation of1 by ferric hydroxide1 #fg4 -- properties of1 #fc4 -- removal of1 from yeast-juice1 #ei4 -- separation from phosphate and hexosephosphate1 #fg4 ,concentration of sugar1 effect of1 on fermentation by yeast-juice1 #cd1 ,,dauerhefe1 #ch4 ,diastatic enzyme of yeast-juice1 #cc4 ,dihydroxyacetone1 fermentability of1 #ajd4 -- formation of1 in fermentation1 #aje4 ,dried yeast 7,lebedeff71 #bd1 #ch4 ,,endotryptase1 #bj4 ,enzyme action1 laws of1 #aba4 ,enzymes1 combined with protoplasm1 #abf4 ,equation of alcoholic fermentation1 #ea4 ,,fermentation by yeast-juice1 causes of cessation of1 #fd4 ,fermenting complex1 #fc4 -- power of yeast-juice1 estimation of1 #bg4 ,formaldehyde1 production of in alcoholic fermentation1 #aag4 ,formic acid theory of fermentation1 #aad4 ,fructose1 fermentation of1 by yeast-juice1 #cb4 -- -- in presence of phosphate1 #gc4 -- relation of1 to fermenting complex1 #gd4 ,fusel oil1 formation of1 from amino-acids1 #he4 ,,galactose1 fermentation of1 by yeast1 #aca4 -- fermentation of1 by yeast-juice1 #cb4 ,glucose1 fermentation of1 by yeast-juice1 #cb4 ,glyceraldehyde1 fermentability of1 #ajd4 ,glyceric acid1 fermentation of1 #ajh4 ,glycerol1 formation in fermentation1 #ie4 ,glycogen as an intermediate product of alcoholic fermentation1 #aaf4 -- fermentation of1 by yeast-juice1 #cc4 -- removal of1 from yeast1 #ci4 ,grinding of yeast by hand1 #bb4 -- -- -- mechanical1 #bc4 ,glutamic acid1 decomposition of1 by yeast1 #ij4 ,,hefanol1 #ch4 ,hexosediphosphoric acid phenylhydrazone1 hydrazine salt of1 #ej4 ,hexosemonophosphoric acid osazone1 hydrazine salt of1 #ej4 ,hexosephosphatase1 #ed4 -- effect of arsenate and arsenite on action of1 #gi4 ,hexosephosphate1 constitution of1 #ea4 -- enzymic decomposition of1 in yeast-juice1 #ef4 -- -- hydrolysis of1 #ea4 -- formation of1 #dh4 -- hydrolysis of1 by acids1 #di4 -- preparation of1 #dh4 -- properties of1 #di4 -- theory of formation of1 #eg1 #aag1 ,hexoses1 action of alkalis on1 #if1 ,,isoamyl alcohol1 formation from leucine1 #hg4 ,isoleucine1 decomposition of1 by yeast1 #hg4 -,,ketonic acids1 fermentation of1 #ha4 ,,lactic acid1 destruction of1 by yeast-juice1 #ajb4 -- -- formation from sugars by alkalis1 #ig4 -- -- -- of1 in yeast-juice1 #ajb4 -- -- non-fermentability of1 by yeast1 #ajc4 -- -- theory of fermentation1 #ajb4 ,leucine1 decomposition of1 by yeast1 #hg4 ,,maceration extract1 preparation of1 #be4 ,mannose1 fermentation of1 by yeast1 #aca4 -- -- of by yeast-juice1 #cb4 ,methylglyoxal1 conversion of1 into lactic acid1 #aja4 -- non-fermentability of1 #ajd4 -- as an intermediate product of alcoholic fermentation1 #aac4 ,,oxalacetic acid1 formation of1 from tartaric acid1 #aja4 ,,permanent yeast1 #ch4 ,phenylethyl alcohol1 #hh4 ,phosphate1 changes of1 in alcoholic fermentation1 #dg4 -- effect of1 on fermentation by yeast-juice1 #db4 -- -- -- -- -- by zymin1 #df4 -- -- -- -- -- of fructose1 #gc4 -- -- of on total fermentation of yeast-juice1 #ed4 -- influence on fermentation of concentration of1 #ga4 -- inhibition by1 #ga4 ,phosphates1 essential for alcoholic fermentation1 #ee4 ,proteoclastic enzyme of yeast1 #bj4 ,protoplasmic theory of activity of yeast-juice1 #ai4 ,pyruvic acid1 fermentation of1 #ha4 -- -- theory of fermentation1 #aji4 ,,rate of fermentation1 controlling factors of1 #aai4 ,reductase1 intervention of1 in alcoholic fermentation1 #aaa4 ,,serum1 effect of1 on fermentation by yeast-juice1 #da4 ,succinic acid1 formation of1 in fermentation1 #hi4 -- -- formed from glutamic acid by yeast1 #ij4 ,synthetic enzyme in yeast-juice1 #cb4 ,,temperature coefficient of fermentation by yeast1 #abi4 -- -- -- -- by zymin1 #abb4 -- -- -- esterification of phosphoric acid by yeast extract1 #eh4 ,tryptophol1 #hh4 ,tyrosol1 #hh4 ,,wohl',s theory of fermentation1 #aja4 ,,yeast1 action of toluene on1 #abd4 -- and yeast-juice1 fermentation by1 compared1 #bi1 #abd4 -- discovery of the vegetable nature of1 #e4 -- fermentation by1 #abg4 -- -- of different sugars by1 #acj4 -- influence of concentration of dextrose on fermentation by1 #abh4 -- -- -- -- of1 on rate of fermentation1 #abi4 -- -- of toluene on autofermentation of1 #abf4 -- nature of the process of fermentation by1 #abc4 -- temperature coefficient of fermentation by1 #abi4 -- theories of fermentation by1 #acc4 ,yeast-juice and yeast1 fermenting powers compared1 #bi1 #abd4 -- co-enzyme of1 #ei4 -- dialysis of1 #ei1 #fb4 -- effect of arsenate on fermentation by1 #ge4 -- -- of concentration of sugar on fermentation by1 #cd4 -- -- of dilution on fermentation by1 #ce4 -- -- of phosphate on total fermentation1 produced by1 #ed4 -- estimation of fermenting power of1 #bg4 -- evaporation of1 #cg4 -- filtration of through gelatin filter1 #ei4 -- precipitation of1 #ch4 -- preparation of1 #ba4 -- properties of1 #ai4 -- ratio of alcohol and carbon dioxide1 produced by1 #cj4 -- synthesis of complex carbohydrate by1 #ca4 -- variation of rate of fermentation by1 with concentration of sugar1 #aba4 ,,zymase1 ,buchner's discovery of1 #af4 -- enzymic destruction of1 #fd4 -- properties of1 #ah4 -- regeneration of inactive1 #fd4 -- separation from co-enzyme1 #ei4 ,zymin1 #ba1 #ch4 -- fermentation by1 #ci4 -- rate of fermentation by1 #ci4 -- temperature coefficient of fermentation by1 #abb4 ,,aberdeen3 ,,the ,,university ,,press ,,transcriber',s ,,endnote4 ,full stops1 middle dots 1 or even dots aligned with the top of the font were variably used in the original as decimal points1 and also for denoting chemical bonding4 ,these have been rendered as middle dots herein4 ,tables and formulas have been edited for clarity and readability1 while honoring the original form4 ,in particular1 some tables and chemical equations were made more compact to control line length4 ,the reference to ,colin's paper on page #e has been changed from #ahbf to #ahbe1 to agree with the corresponding entry in the ,bibliography4 ,the reference to ,turpin's paper on page #h was changed to #ahch from #ahci1 for the same reason4 ,on page #ic1 the complex reaction system has been revised into four simple reactions4 ,the unbalanced original equations have been retained4 ,similarly on page #id1 the original large diagram was converted into four simple reactions4 ,the incorrect formula for the enol ,,ii4 in the equation for glucose dehydration near bottom of page #aja was corrected4 ,equations 7#a7 on page #ajh showing production of glyceric acid from glyceraldehyde have been simplified and clarified4