See James Ferguson,Robert Ferguson, the Plotter(Edinburgh, 1887), which gives a favourable account of Ferguson.
See James Ferguson,Robert Ferguson, the Plotter(Edinburgh, 1887), which gives a favourable account of Ferguson.
FERGUSON, SIR SAMUEL(1810-1886), Irish poet and antiquary, was born at Belfast, on the 10th of March 1810. He was educated at Trinity College, Dublin, was called to the Irish bar in 1838, and was made Q.C. in 1859, but in 1867 retired from practice upon his appointment as deputy-keeper of the Irish records, then in a much neglected condition. He was an excellent civil servant, and was knighted in 1878 for his services to the department. His spare time was given to general literature, and in particular to poetry. He had long been a leading contributor to theDublin University Magazineand toBlackwood, where he had published his two literary masterpieces, “The Forging of the Anchor,” one of the finest of modern ballads, and the humorous prose extravaganza of “Father Tom and the Pope.” He publishedLays of the Western Gaelin 1865,Poemsin 1880, and in 1872Congal, a metrical narrative of the heroic age of Ireland, and, though far from ideal perfection, perhaps the most successful attempt yet made by a modern Irish poet to revivify the spirit of the past in a poem of epic proportions. Lyrics have succeeded better in other hands; many of Ferguson’s pieces on modern themes, notably his “Lament for Thomas Davis” (1845), are, nevertheless, excellent. He was an extensive contributor on antiquarian subjects to theTransactions of the Royal Irish Academy, and was elected its president in 1882. His manners were delightful, and his hospitality was boundless. He died at Howth on the 9th of August 1886. His most important antiquarian work,Ogham Inscriptions in Ireland, Wales, Scotland, was published in the year after his death.
SeeSir Samuel Ferguson in the Ireland of his Day(1896), by his wife, Mary C. Ferguson; also an article by A.P. Graves inA Treasury of Irish Poetry in the English Tongue(1900), edited by Stopford Brooke and T.W. Rolleston.
SeeSir Samuel Ferguson in the Ireland of his Day(1896), by his wife, Mary C. Ferguson; also an article by A.P. Graves inA Treasury of Irish Poetry in the English Tongue(1900), edited by Stopford Brooke and T.W. Rolleston.
FERGUSSON, JAMES(1808-1886), Scottish writer on architecture, was born at Ayr on the 22nd of January 1808. His father was an army surgeon. After being educated first at the Edinburgh high school, and afterwards at a private school at Hounslow, James went to Calcutta as partner in a mercantile house. Here he was attracted by the remains of the ancient architecture of India, little known or understood at that time. The successful conduct of an indigo factory, as he states in his own account, enabled him in about ten years to retire from business and settle in London. The observations made on Indian architecture were first embodied in his book onThe Rock-cut Temples of India, published in 1845. The task of analysing the historic and aesthetic relations of this type of ancient buildings led him further to undertake a historical and critical comparative survey of the whole subject of architecture inThe Handbook of Architecture, a work which first appeared in 1855. This did not satisfy him, and the work was reissued ten years later in a much more extended form under the title ofThe History of Architecture. The chapters on Indian architecture, which had been considered at rather disproportionate length in theHandbook, were removed from the generalHistory, and the whole of this subject treated more fully in a separate volume,The History of Indian and Eastern Architecture, which appeared in 1876, and, although complete in itself, formed a kind of appendix toThe History of Architecture. Previously to this, in 1862, he issued hisHistory of Modern Architecture, in which the subject was continued from the Renaissance to the present day, the period of “modern architecture” being distinguished as that of revivals and imitations of ancient styles, which began with the Renaissance. The essential difference between this and the spontaneously evolved architecture of preceding ages Fergusson was the first clearly to point out and characterize. His treatise onThe True Principles of Beauty in Art, an early publication, is a most thoughtful metaphysical study. Some of his essays on special points in archaeology, such as the treatise onThe Mode in which Light was introduced into Greek Temples, included theories which have not received general acceptance. His real monument is hisHistory of Architecture(later edition revised by R. Phenè Spiers), which, for grasp of the whole subject, comprehensiveness of plan, and thoughtful critical analysis, stands quite alone in architectural literature. He received the gold medal of the Royal Institute of British Architects in 1871. Among his works, besides those already mentioned, are:A Proposed New System of Fortification(1849),Palaces of Nineveh and Persepolis restored(1851),Mausoleum at Halicarnassus restored(1862),Tree and Serpent Worship(1868),Rude Stone Monuments in all Countries(1872), andThe Temples of the Jews and the other Buildings in the Haram Area at Jerusalem(1878). The sessional papers of the Institute of British Architects include papers by him onThe History of the Pointed Arch,Architecture of Southern India,Architectural Splendour of the City of Beejapore,On the Erechtheumand on theTemple of Diana at Ephesus.
Although Fergusson never practised architecture he took a keen interest in all the professional work of his time. He was adviser with Austen Layard in the scheme of decoration for the Assyrian court at the Crystal Palace, and indeed assumed in 1856 the duties of general manager to the Palace Company, a post which he held for two years. In 1847 Fergusson had published an “Essay on the Ancient Topography of Jerusalem,” in which he had contended that the “Mosque of Omar” was the identical church built by Constantine the Great over the tomb of our Lord at Jerusalem, and that it, and not the present church of the Holy Sepulchre, was the genuine burial-place of Jesus. The burden of this contention was further explained by the publication in 1860 of hisNotes on the Site of the Holy Sepulchre at Jerusalem; andThe Temples of the Jews and the other Buildings in the Haram Area at Jerusalem, published in 1878, was a still completer elaboration of these theories, which are said to have been the origin of the establishment of the Palestine Exploration fund. His manifold activities continued till his death, which took place in London on the 9th of January 1886.
FERGUSSON, ROBERT(1750-1774), Scottish poet, son of Sir William Fergusson, a clerk in the British Linen Company, was born at Edinburgh on the 5th of September 1750. Robert was educated at the grammar school of Dundee, and at the university of St Andrews, where he matriculated in 1765. His father died while he was still at college; but a bursary enabled him to complete his four years of study. He refused to study for the church, and was too nervous to study medicine as his friends wished. He quarrelled with his uncle, John Forbes of Round Lichnot, Aberdeenshire, and went to Edinburgh, where he obtained employment as copying clerk in a lawyer’s office. In this humble occupation he passed the remainder of his life. While at college he had written a clever elegy on Dr David Gregory, and in 1771 he began to contribute verses regularly to Ruddiman’sWeekly Magazine. He was a member of the Cape Club, celebrated by him in his poem of “Auld Reekie.” “The Knights of the Cape” assembled at a tavern in Craig’s Close, in the vicinity of the Cross; each member had a name and character assigned to him, which he was required to maintain at all gatherings of the order. David Herd (1732-1810), the collector of the classic edition ofAncient and Modern Scottish Songs(1776), was sovereign of the Cape (in which he was known as “Sir Scrape”) when Fergusson was dubbed a knight of the order, with the title of “Sir Precentor,” in allusion to his fine voice. Alexander Runciman, the historical painter, his pupil Jacob More, and Sir Henry Raeburn were all members. The old minute books of the club abound with pencilled sketches by them, one of the most interesting of which, ascribed to Runciman’s pencil, is a sketch of Fergusson in his character of “Sir Precentor.”
Fergusson’s gaiety and wit made him an entertaining companion, and he indulged too freely in the convivial habits of the time. After a meeting with John Brown of Haddington he became, however, very serious, and would read nothing but his Bible. A fall by which his head was severely injured aggravated symptoms of mental aberration which had begun to show themselves; and after about two months’ confinement in the old Darien House—then the only public asylum in Edinburgh—the poet died on the 16th of October 1774.
Fergusson’spoems were collected in the year before his death. The influence of his writings on Robert Burns is undoubted. His “Leith Races” unquestionably supplied the model for the “Holy Fair.” Not only is the stanza the same, but the Mirth who plays the part of conductor to Fergusson, and the Fun who renders a like service to Burns, are manifestly conceived on the same model. “The Mutual Complaint of Plainstanes and Causey” probably suggested “The Brigs of Ayr”; “On seeing a Butterfly in the Street” has reflections in it which strikingly correspond with “To a Mouse”; nor will a comparison of “The Farmer’s Ingle” of the elder poet with “The Cottar’s Saturday Night” admit of a doubt as to the influence of the city-bred poet’s muse on that exquisite picturing of homely peasant life. Burns was himself the first to render a generous tribute to the merits of Fergusson; on his visit to Edinburgh in 1787 he sought out the poet’s grave, and petitioned the authorities of the Canongate burying-ground for permission to erect the memorial stone which is preserved in the existing monument. The date there assigned for his birth differs from the one given above, which rests on the authority of his younger sister Margaret.
The first edition of Fergusson’s poems was published by Ruddiman at Edinburgh in 1773, and a supplement containing additional poems, in 1779. A second edition appeared in 1785. There are later editions, by Robert Chambers (1850) and Dr A.B. Grosart (1851). A life of Fergusson is included in Dr David Irving’sLives of the Scottish Poets, and in Robert Chambers’s Lives ofIllustrious and Distinguished Scotsmen.
The first edition of Fergusson’s poems was published by Ruddiman at Edinburgh in 1773, and a supplement containing additional poems, in 1779. A second edition appeared in 1785. There are later editions, by Robert Chambers (1850) and Dr A.B. Grosart (1851). A life of Fergusson is included in Dr David Irving’sLives of the Scottish Poets, and in Robert Chambers’s Lives ofIllustrious and Distinguished Scotsmen.
FERGUSSON, SIR WILLIAM,Bart. (1808-1877), British surgeon, the son of James Fergusson of Lochmaben, Dumfriesshire, was born at Prestonpans, East Lothian, on the 20th of March 1808. After receiving his early education at Lochmaben and the high school of Edinburgh, he entered the university of Edinburgh with the view of studying law, but soon afterwards abandoned his intention and became a pupil of the anatomist Robert Knox (1791-1862) whose demonstrator he wasappointed at the age of twenty. In 1836 he succeeded Robert Liston as surgeon to the Edinburgh Royal Infirmary, and coming to London in 1840 as professor of surgery in King’s College, and surgeon to King’s College Hospital, he acquired a commanding position among the surgeons of the metropolis. He revived the operation for cleft-palate, which for many years had fallen into disrepute, and invented a special mouth-gag for the same. He also devised many other surgical instruments, chief among which, and still in use to-day, are his bone forceps, lion forceps and vaginal speculum. In 1866 he was created a baronet. He died in London on the 10th of February 1877. As a surgeon Fergusson’s greatest merit is that of having introduced the practice of “conservative surgery,” by which he meant the excision of a joint rather than the amputation of a limb. He made his diagnosis with almost intuitive certainty; as an operator he was characterized by self-possession in the most critical circumstances, by minute attention to details and by great refinement of touch, and he relied more on his mechanical dexterity than on complicated instruments. He was the author ofThe Progress of Anatomy and Surgery in the Nineteenth Century(1867), and of aSystem of Practical Surgery(1842), which went through several editions.
FERINGHI,orFeringhee, a Frank (Persian,Farangi). This term for a European is very old in Asia, and was originally used in a purely geographical sense, but now generally carries a hostile or contemptuous significance. The combatants on either side during the Indian Mutiny called each other Feringhies and Pandies.
FERISHTA, MAHOMMED KASIM(c. 1570-c. 1611), Persian historian, was born at Astrabad, on the shores of the Caspian Sea. While he was still a child his father was summoned away from his native country into Hindostan, where he held high office in the Deccan; and by his influence the young Ferishta received court promotion. In 1589 Ferishta removed to Bijapur, where he spent the remainder of his life under the immediate protection of the shah Ibrahim Adil II., who engaged him to write a history of India. At the court of this monarch he died about 1611. In the introduction to his work arésuméis given of the history of Hindostan prior to the times of the Mahommedan conquest, and also of the victorious progress of the Arabs through the East. The first ten books are each occupied with a history of the kings of one of the provinces; the eleventh book gives an account of the Mussulmans of Malabar; the twelfth a history of the Mussulman saints of India; and the conclusion treats of the geography and climate of India. Ferishta is reputed one of the most trustworthy of the Oriental historians, and his work still maintains a high place as an authority. Several portions of it have been translated into English; but the best as well as the most complete translation is that published by General J. Briggs under the title ofThe History of the Rise of the Mahometan Power in India(London, 1829, 4 vols. 8vo). Several additions were made by Briggs to the original work of Ferishta, but he omitted the whole of the twelfth book, and various other passages which had been omitted in the copy from which he translated.
FERMANAGH,a county of Ireland, in the province of Ulster, bounded N.W. by Donegal, N.E. by Tyrone, E. by Monaghan and S.W. by Cavan and Leitrim. The area is 457,369 acres or about 715 sq. m. The county is situated mostly in the basin of the Erne, which divides the county into two nearly equal sections. Its surface is hilly, and its appearance (in many parts) somewhat sterile, though in the main, and especially in the neighbourhood of Lough Erne, it is picturesque and attractive. The climate, though moist, is healthy, and the people are generally tall and robust. The chief mountains are Cuilcagh (2188 ft.), partly in Leitrim and Cavan, Belmore (1312), Glenkeel (1223), North Shean (1135), Tappahan (1110), Carnmore (1034). Tossett or Toppid and Turaw mountains command extensive prospects, and form striking features in the scenery of the county. But the most distinguishing features of Fermanagh are the Upper and Lower Loughs Erne, which occupy a great extent of its surface, stretching for about 45 m. from S.E. to N.W. These lakes are expansions of the river Erne, which enters the county from Cavan at Wattle Bridge. It passes Belturbet, the Loughs Erne, Enniskillen and Belleek, on its way to the Atlantic, into which it descends at Ballyshannon. At Belleek it forms a considerable waterfall and is here well known to sportsmen for its good salmon fishing. Trout are taken in most of the loughs, and pike of great size in the Loughs Erne. There are several mineral springs in the county, some of them chalybeate, others sulphurous. At Belcoo, near Enniskillen, there is a famous well called Daragh Phadric, held in repute by the peasantry for its cure of paralytic and other diseases; and 4 m. N.W. of the same town, at a place called “the Daughton,” are natural caves of considerable size.
This county includes in the north an area of the gneiss that is discussed under county Donegal, and, west of Omagh, a metamorphic region that stretches in from the central axis of Tyrone. A fault divides the latter from the mass of red-brown Old Red Sandstone that spreads south nearly to Enniskillen. Lower Carboniferous sandstone and limestone occur on the north of Lower Lough Erne. The limestone forms fine scarps on the southern side of the lake, capped by beds regarded as the Yoredale series. The scenery about the two Loughs Macnean is carved out in similarly scarped hills, rising to 2188 ft. in Cuilcagh on the south. The “Marble Arch” cave near Florence-court, with its emerging river, is a characteristic example of the subterranean waterways in the limestone. Upper Lough Erne is a typical meandering lake of the limestone lowland, with outliers of higher Carboniferous strata forming highlands north-east and south-west of it.
With the exception of the pottery works at Belleek, where iridescent ware of good quality is produced, Fermanagh has no distinguishing manufactures. It is chiefly an agricultural county. The proportion of tillage to pasture is roughly as 1 to 2½. Cattle and poultry are the principal classes of live stock. Oats and potatoes are the crops most extensively cultivated. The north-western division of the Great Northern railway passes through the most populous portion of the county, one branch connecting Enniskillen with Clones, another connecting Enniskillen with Londonderry via Omagh, and a third connecting Bundoran Junction with Bundoran, in county Donegal. The Sligo, Leitrim & Northern Counties railway connects with the Great Northern at Enniskillen, and the Clogher Valley light railway connects southern county Tyrone with the Great Northern at Maguiresbridge.
The population (74,170 in 1891; 65,430 in 1901; almost wholly rural) shows a decrease among the most serious of the county populations of Ireland. It includes 55% of Roman Catholics and about 35% of Protestant Episcopalians. Enniskillen (the county town, pop. 5412) is the only town of importance, the rest being little more than villages. The principal are Lisnaskea, Irvinestown (formerly Lowtherstown), Maguiresbridge, Tempo, Newtownbutler, Belleek, Derrygonnelly and Kesh, at which fairs are held. Garrison, a fishing station on the wild Lough Melvin, and Pettigo, near to the lower Lough Erne, are market villages. Fermanagh returns two members to parliament, one each for the north and south divisions. It comprises eight baronies and nineteen civil parishes. The assizes are held at Enniskillen, quarter sessions at Enniskillen and Newtownbutler. The headquarters of the constabulary are at Enniskillen. Ecclesiastically it belongs to the Protestant and Roman Catholic dioceses of Clogher and Kilmore.
By the ancient Irish the district was calledFeor-magh-Eanagh, or the “country of the lakes” (lit. “the mountain-valley marsh district”); and also Magh-uire, or “the country of the waters.” A large portion was occupied by theGuarii, the ancestors of the MacGuires or Maguires, a name still common in the district. This family was so influential that for centuries the county was called after it Maguire’s Country, and one of the towns still existing bears its name, Maguiresbridge. Fermanagh was formed into a county on the shiring of Ulster in 1585 by Sir John Perrot, and was included in the well-known scheme of colonization of James I., the Plantation of Ulster. In 1689 battles were fought between William III.’s army and the Irishunder Macarthy (for James II.), Lisnaskea (26th July) and Newtownbutler (30th July). The chief place of interest to the antiquary is Devenish Island in Lough Erne, about 2½ m. N.W. from Enniskillen (q.v.), with its ruined abbey, round tower and cross. In various places throughout the county may be seen the ruins of several ancient castles, Danish raths or encampments, and tumuli, in the last of which urns and stone coffins have sometimes been found. The round tower on Devenish Island is one of the finest examples in the country.
FERMAT, PIERRE DE(1601-1665), French mathematician, was born on the 17th of August 1601, at Beaumont-de-Lomagne near Montauban. While still young, he, along with Blaise Pascal, made some discoveries in regard to the properties of numbers, on which he afterwards built his method of calculating probabilities. He discovered a simpler method of quadrating parabolas than that of Archimedes, and a method of finding the greatest and the smallest ordinates of curved lines analogous to that of the then unknown differential calculus. His great workDe maximis et minimisbrought him into conflict with René Descartes, but the dispute was chiefly due to a want of explicitness in the statement of Fermat (seeInfinitesimal Calculus). His brilliant researches in the theory of numbers entitle him to rank as the founder of the modern theory. They originally took the form of marginal notes in a copy of Bachet’sDiophantus, and were published in 1670 by his son Samuel, who incorporated them in a new edition of this Greek writer. Other theorems were published in hisOpera Varia, and in John Wallis’sCommercium epistolicum(1658). He died in the belief that he had found a relation which every prime number must satisfy, namely 22n+ 1 = a prime. This was afterwards disproved by Leonhard Euler for the case when n = 5.Fermat’s Theorem, if p is prime and a is prime to p then ap−1− 1 is divisible by p, was first given in a letter of 1640.Fermat’s Problemis that xn+ yn= znis impossible for integral values of x, y and z when n is greater than 2.
Fermat was for some time councillor for the parliament of Toulouse, and in the discharge of the duties of that office he was distinguished both for legal knowledge and for strict integrity of conduct. Though the sciences were the principal objects of his private studies, he was also an accomplished general scholar and an excellent linguist. He died at Toulouse on the 12th of January 1665. He left a son, Samuel de Fermat (1630-1690) who published translations of several Greek authors and wrote certain books on law in addition to editing his father’s works.
TheOpera mathematicaof Fermat were published at Toulouse, in 2 vols. folio, 1670 and 1679. The first contains the “Arithmetic of Diophantus,” with notes and additions. The second includes a “Method for the Quadrature of Parabolas,” and a treatise “on Maxima and Minima, on Tangents, and on Centres of Gravity,” containing the same solutions of a variety of problems as were afterwards incorporated into the more extensive method of fluxions by Newton and Leibnitz. In the same volume are treatises on “Geometric Loci, or Spherical Tangencies,” and on the “Rectification of Curves,” besides a restoration of “Apollonius’s Plane Loci,” together with the author’s correspondence addressed to Descartes, Pascal, Roberval, Huygens and others. TheŒuvresof Fermat have been re-edited by P. Tannery and C. Henry (Paris, 1891-1894).See Paul Tannery, “Sur la date des principales découvertes de Fermat,” in theBulletin Darboux(1883); and “Les Manuscrits de Fermat,” in theAnnales de la faculté des lettres de Bordeaux.
TheOpera mathematicaof Fermat were published at Toulouse, in 2 vols. folio, 1670 and 1679. The first contains the “Arithmetic of Diophantus,” with notes and additions. The second includes a “Method for the Quadrature of Parabolas,” and a treatise “on Maxima and Minima, on Tangents, and on Centres of Gravity,” containing the same solutions of a variety of problems as were afterwards incorporated into the more extensive method of fluxions by Newton and Leibnitz. In the same volume are treatises on “Geometric Loci, or Spherical Tangencies,” and on the “Rectification of Curves,” besides a restoration of “Apollonius’s Plane Loci,” together with the author’s correspondence addressed to Descartes, Pascal, Roberval, Huygens and others. TheŒuvresof Fermat have been re-edited by P. Tannery and C. Henry (Paris, 1891-1894).
See Paul Tannery, “Sur la date des principales découvertes de Fermat,” in theBulletin Darboux(1883); and “Les Manuscrits de Fermat,” in theAnnales de la faculté des lettres de Bordeaux.
FERMENTATION.The process of fermentation in the preparation of wine, vinegar, beer and bread was known and practised in prehistoric times. The alchemists used the terms fermentation, digestion and putrefaction indiscriminately; any reaction in which chemical energy was displayed in some form or other—such, for instance, as the effervescence occasioned by the addition of an acid to an alkaline solution—was described as a fermentation (Lat.fervere, to boil); and the idea of the “Philosopher’s Stone” setting up a fermentation in the common metals and developing the essence or germ, which should transmute them into silver or gold, further complicated the conception of fermentation. As an outcome of this alchemical doctrine the process of fermentation was supposed to have a purifying and elevating effect on the bodies which had been submitted to its influence. Basil Valentine wrote that when yeast was added to wort “an internal inflammation is communicated to the liquid, so that it raises in itself, and thus the segregation and separation of the feculent from the clear takes place.” Johann Becher, in 1669, first found that alcohol was formed during the fermentation of solutions of sugar; he distinguished also between fermentation and putrefaction. In 1697 Georg Stahl admitted that fermentation and putrefaction were analogous processes, but that the former was a particular case of the latter.
The beginning of definite knowledge on the phenomenon of fermentation may be dated from the time of Antony Leeuwenhoek, who in 1680 designed a microscope sufficiently powerful to render yeast cells and bacteria visible; and a description of these organisms, accompanied by diagrams, was sent to the Royal Society of London. This investigator just missed a great discovery, for he did not consider the spherical forms to be living organisms but compared them with starch granules. It was not until 1803 that L.J. Thénard stated that yeast was the cause of fermentation, and held it to be of an animal nature, since it contained nitrogen and yielded ammonia on distillation, nor was it conclusively proved that the yeast cell was the originator of fermentation until the researches of C. Cagniard de la Tour, T. Schwann and F. Kützing from 1836 to 1839 settled the point. These investigators regarded yeast as a plant, and Meyer gave to the germs the systematic name of “Saccharomyces” (sugar fungus). In 1839-1840 J. von Liebig attacked the doctrine that fermentation was caused by micro-organisms, and enunciated his theory of mechanical decomposition. He held that every fermentation consisted of molecular motion which is transmitted from a substance in a state of chemical motion—that is, of decomposition—to other substances, the elements of which are loosely held together. It is clear from Liebig’s publications that he first regarded yeast as a lifeless, albuminoid mass; but, although later he considered they were living cells, he would never admit that fermentation was a physiological process, the chemical aspect being paramount in the mind of this distinguished investigator.
In 1857 Pasteur decisively proved that fermentation was a physiological process, for he showed that the yeast which produced fermentation was no dead mass, as assumed by Liebig, but consisted of living organisms capable of growth and multiplication. His own words are: “The chemical action of fermentation is essentially a correlative phenomenon of a vital act, beginning and ending with it. I think that there is never any alcoholic fermentation without there being at the same time organization, development and multiplication of globules, or the continued consecutive life of globules already formed.” Fermentation, according to Pasteur, was caused by the growth and multiplication of unicellular organisms out of contact with free oxygen, under which circumstance they acquire the power of taking oxygen from chemical compounds in the medium in which they are growing. In other words “fermentation is life without air, or life without oxygen.” This theory of fermentation was materially modified in 1892 and 1894 by A.J. Brown, who described experiments which were in disagreement with Pasteur’s dictum. A.J. Brown writes: “If for the theory ’life without air’ is substituted the consideration that yeast cells can use oxygen in the manner of ordinary aërobic fungi, and probably do require it for the full completion of their life-history, but that the exhibition of their fermentative functions is independent of their environment with regard to free oxygen, it will be found that there is nothing contradictory in Pasteur’s experiments to such a hypothesis.”
Liebig and Pasteur were in agreement on the point that fermentation is intimately connected with the presence of yeast in the fermenting liquid, but their explanations concerning the mechanism of fermentation were quite opposed. According to M. Traube (1858), the active cause of fermentation is due to the action of different enzymes contained in yeast and not to the yeast cell itself. As will be seen later this theory was confirmed by subsequent researches of E. Fischer and E. Buchner.
In 1879 C. Nägeli formulated his well-known molecular-physical theory, which supported Liebig’s chemical theory on the one hand and Pasteur’s physiological hypothesis on theother: “Fermentation is the transference of the condition of motion of the molecules, atomic groups and atoms of the various compounds constituting the living plasma, to the fermenting material, in consequence of which equilibrium in the molecules of the latter is destroyed, the result being their disintegration.” He agreed with Pasteur that the presence of living cells is essential to the transformation of sugar into alcohol, but dissented from the view that the process occurs within the cell. This investigator held that the decomposition of the sugar molecules takes place outside the cell wall. In 1894 and 1895, Fischer, in a remarkable series of papers on the influence of molecular structure upon the action of the enzyme, showed that various species of yeast behave very differently towards solutions of sugars. For example, some species hydrolysecanesugar and maltose, and then carry on fermentation at the expense of the simple sugars (hexoses) so formed.Saccharomyces Marxianuswill not hydrolyse maltose, but it does attack cane sugar and ferment the products of hydrolysis. Fischer next suggested that enzymes can only hydrolyse those sugars which possess a molecular structure in harmony with their own, or to use his ingenious analogy, “the one may be said to fit into the other as a key fits into a lock.” The preference exhibited by yeast cells for sugar molecules is shared by mould fungi and soluble enzymes in their fermentative actions. Thus, Pasteur showed thatPenicillium glaucum, when grown in an aqueous solution of ammonium racemate, decomposed the dextro-tartrate, leaving the laevo-tartrate, and the solution which was originally inactive to polarized light became dextro-rotatory. Fischer found that the enzyme “invertase,” which is present in yeast, attacks methyl-d-glucoside but not methyl-l-glucoside.
In 1897 Buchner submitted yeast to great pressure, and isolated a nitrogenous substance, enzymic in character, which he termed “zymase.” This body is being continually formed in the yeast cell, and decomposes the sugar which has diffused into the cell. The freshly-expressed yeast juice causes concentrated solutions of cane sugar, glucose, laevulose and maltose to ferment with the production of alcohol and carbon dioxide, but not milk-sugar and mannose. In this respect the plasma behaves in a similar manner towards the sugars as does the living yeast cell. Pasteur found that, when cane sugar was fermented by yeast, 49.4% of carbonic acid and 51.1% of alcohol were produced; with expressed yeast juice cane sugar yields 47% of carbonic acid and 47.7% of alcohol. According to Buchner the fermentative activity of yeast-cell juice is not due to the presence of living yeast cells, or to the action of living yeast protoplasm, but it is caused by a soluble enzyme. A. Macfadyen, G.H. Morris and S. Rowland, in repeating Buchner’s experiments, found that zymase possessed properties differing from all other enzymes, thus: dilution with twice its volume of water practically destroys the fermentative power of the yeast juice. These investigators considered that differences of this nature cannot be explained by the theory that it is a soluble enzyme, which brings about the alcoholic fermentation of sugar. The remarkable discoveries of Fischer and Buchner to a great extent confirm Traube’s views, and reconcile Liebig’s and Pasteur’s theories. Although the action of zymase may be regarded as mechanical, the enzyme cannot be produced by any other than living protoplasm.
Pasteur’s important researches mark an epoch in the technical aspect of fermentation. His investigations on vinegar-making revolutionized that industry, and he showed how, instead of waiting two or three months for the elaboration of the process, the vinegar could be made in eight or ten days by exposing the vats containing the mixture of wine and vinegar to a temperature of 20° to 25° C., and sowing with a small quantity of the acetic organism. To the study of the life-history of the butyric and acetic organisms we owe the terms “anaërobic” and “aërobic.” His researches from 1860 and onwards on the then vexed question of spontaneous generation proved that, in all cases where spontaneous generation appeared to have taken place, some defect or other was in the experiment. Although the direct object of Pasteur was to prove a negative, yet it was on these experiments that sterilization as known to us was developed. It is only necessary to bear in mind the great part played by sterilization in the laboratory, and pasteurization on the fermentation industries and in the preservation of food materials. Pasteur first formulated the idea that bacteria are responsible for the diseases of fermented liquids; the corollary of this was a demand for pure yeast. He recommended that yeast should be purified by cultivating it in a solution of sugar containing tartaric acid, or, in wort containing a small quantity of phenol. It was not recognized that many of the diseases of fermented liquids are occasioned by foreign yeasts; moreover, this process, as was shown later by Hansen, favours the development of foreign yeasts at the expense of the good yeast.
About this time Hansen, who had long been engaged in researches on the biology of the fungi of fermentation, demonstrated that yeast free from bacteria could nevertheless occasion diseases in beer. This discovery was of great importance to the zymo-technical industries, for it showed that bacteria are not the only undesirable organisms which may occur in yeast. Hansen set himself the task of studying the properties of the varieties of yeast, and to do this he had to cultivate each variety in a pure state. Having found that some of the commonest diseases of beer, such as yeast turbidity and the objectionable changes in flavour, were caused not by bacteria but by certain species of yeast, and, further, that different species of good brewery yeast would produce beers of different character, Hansen argued that the pitching yeast should consist only of a single species—namely, that best suited to the brewery in question. These views met with considerable opposition, but in 1890 Professor E. Duclaux stated that the yeast question as regards low fermentation has been solved by Hansen’s investigations. He emphasized the opinion that yeast derived from one cell was of no good for top fermentation, and advocated Pasteur’s method of purification. But in the course of time, notwithstanding many criticisms and objections, the reform spread from bottom fermentation to top fermentation breweries on the continent and in America. In the United Kingdom the employment of brewery yeasts selected from a single cell has not come into general use; it may probably be accounted for in a great measure by conservatism and the wrong application of Hansen’s theories.
Pure Cultivation of Yeasts.—The methods which were first adopted by Hansen for obtaining pure cultures of yeast were similar in principle to one devised by J. Lister for isolating a pure culture of lactic acid bacterium. Lister determined the number of bacteria present in a drop of the liquid under examination by counting, and then diluted this with a sufficient quantity of sterilized water so that each drop of the mixture should contain, on an average, less than one bacterium. A number of flasks containing a nutrient medium were each inoculated with one drop of this mixture; it was found that some remained sterile, and Lister assumed that the remaining flasks each contained a pure culture. This method did not give very certain results, for it could not be guaranteed that the growth in the inoculated flask was necessarily derived from a single bacterium. Hansen counted the number of yeast cells suspended in a drop of liquid diluted with sterilized water. A volume of the diluted yeast was introduced into flasks containing sterilized wort, the degree of dilution being such that only a small proportion of the flasks became infected. The flasks were then well shaken, and the yeast cell or cells settled to the bottom, and gave rise to a separate yeast speck. Only those cultures which contained a single yeast speck were assumed to be pure cultivations. By this method several races ofSaccharomycetesand brewery yeasts were isolated and described.
The next important advance was the substitution of solid for liquid media; due originally to Schroter. R. Koch subsequently improved the method. He introduced bacteria into liquid sterile nutrient gelatin. After being well shaken, the liquid was poured into a sterile glass Petrie dish and covered with a moist and sterile bell-jar. It was assumed that each separate speck contained a pure culture. Hansen pointed out that thiswas by no means the case, for it is more difficult to separate the cells from each other in the gelatin than in the liquid. To obtain an absolutely pure culture with certainty it is necessary, even when the gelatin method is employed, to start from a single cell. To effect this some of the nutrient gelatin containing yeast cells is placed on the under-surface of the cover-glass of the moist chamber. Those cells are accurately marked, the position of which is such that the colonies, to which they give rise, can grow to their full size without coming into contact with other colonies. The growth of the marked cells is kept under observation for three or four days, by which time the colonies will be large enough to be taken out of the chamber and placed in flasks. The contents of the flasks can then be introduced into larger flasks, and finally into an apparatus suitable for making enough yeast for technical purposes. Such, in brief, are the methods devised by that brilliant investigator Hansen; and these methods have not only been the basis on which our modern knowledge of theSaccharomycetesis founded, but are the only means of attack which the present-day observer has at his disposal.
From the foregoing it will be seen that the term fermentation has now a much wider significance than when it was applied to such changes as the decomposition of must or wort with the production of carbon dioxide and alcohol. Fermentation now includes all changes in organic compounds brought about by ferments elaborated in the living animal or vegetable cell. There are two distinct types of fermentation: (1) those brought about by living organisms (organized ferments), and (2) those brought about by non-living or unorganized ferments (enzymes). The first class include such changes as the alcoholic fermentation of sugar solutions, the acetic acid fermentation of alcohol, the lactic acid fermentation of milk sugar, and the putrefaction of animal and vegetable nitrogenous matter. The second class include all changes brought about by the agency of enzymes, such as the action of diastase on starch, invertase on cane sugar, glucase on maltose, &c. The actions are essentially hydrolytic.
Biological Aspect of Yeast.—The Saccharomycetes belong to that division of the Thallophyta called the Hyphomycetes or Fungi (q.v.). Two great divisions are recognized in the Fungi: (i.) thePhycomycetesor Algal Fungi, which retain a definitely sexual method of reproduction as well as asexual (vegetative) methods, and (ii.) theMycomycetes, characterized by extremely reduced or very doubtful sexual reproduction. The Mycomycetes may be divided as follows: (A) forms bearing both sporangia and conidia (seeFungi), (B) forms bearing conidia only,e.g.the common mushroom. Division A comprises (a) the trueAscomycetes, of which the moulds Eurotium and Penicillium are examples, and (b) theHemiasci, which includes the yeasts. The gradual disappearance of the sexual method of reproduction, as we pass upwards in the fungi from the points of their departure from the Algae, is an important fact, the last traces of sexuality apparently disappearing in the ascomycetes.
With certain rare exceptions the Saccharomycetes have three methods of asexual reproduction:—
1. The most common.—The formation ofbudswhich separate to form new cells. A portion of the nucleus of the parent cell makes its way through the extremely narrow neck into the daughter cell. This method obtains when yeast is vigorously fermenting a saccharine solution.
2. A division byfissionfollowed by Endogenous spore formation, characteristic of the Schizosaccharomycetes. Some species show fermentative power.
3.Endosporeformation, the conditions for which are as follows: (1) suitable temperature, (2) presence of air, (3) presence of moisture, (4) young and vigorous cells, (5) a food supply in the case of one species at least is necessary, and is in no case prejudicial. In some cases a sexual act would appear to precede spore formation. In most cases four spores are formed within the cell by free formation. These may readily be seen after appropriate staining.
In some of the true Ascomycetes, such asPenicillium glaucum, the conidia if grown in saccharine solutions, which they have the power of fermenting, develop single cell yeast-like forms, and do not—at any rate for a time—produce again the characteristic branching mycelium. This is known as theTorulacondition. It is supposed by some that Saccharomyces is a very degraded Ascomycete, in which the Torula condition has become fixed.
The yeast plant and its allies are saprophytes and form no chlorophyll. Their extreme reduction in form and loss of sexuality may be correlated with the saprophytic habit, the proteids and other organic material required for the growth and reproduction being appropriated ready synthesized, the plant having entirely lost the power of forming them for itself, as evidenced by the absence of chlorophyll. The beer yeastS. cerevisiae, is never found wild, but the wine yeasts occur abundantly in the soil of vineyards, and so are always present on the fruit, ready to ferment the expressed juice.
Chemical Aspect of Alcoholic Fermentation.—Lavoisier was the first investigator to study fermentation from a quantitative standpoint. He determined the percentages of carbon, hydrogen and oxygen in the sugar and in the products of fermentation, and concluded that sugar in fermenting breaks up into alcohol, carbonic acid and acetic acid. The elementary composition of sugar and alcohol was fixed in 1815 by analyses made by Gay-Lussac, Thénard and de Saussure. The first-mentioned chemist proposed the following formula to represent the change which takes place when sugar is fermented:—
This formula substantially holds good to the present day, although a number of definite bodies other than carbon dioxide and alcohol occur in small and varying quantities, according to the conditions of the fermentation and the medium fermented. Prominent among these are glycerin and succinic acid. In this connexion Pasteur showed that 100 parts of cane sugar on inversion gave 105.4 parts of invert sugar, which, when fermented, yielded 51.1 parts alcohol, 49.4 carbonic acid, 0.7 succinic acid, 3.2 glycerin and 1.0 unestimated. A. Béchamp and E. Duclaux found that acetic acid is formed in small quantities during fermentation; aldehyde has also been detected. The higher alcohols such as propyl, isobutyl, amyl, capryl, oenanthyl and caproyl, have been identified; and the amount of these vary according to the different conditions of the fermentation. A number of esters are also produced. The characteristic flavour and odour of wines and spirits is dependent on the proportion of higher alcohols, aldehydes and esters which may be produced.
Certain yeasts exercise a reducing action, forming sulphuretted hydrogen, when sulphur is present. The “stinking fermentations” occasionally experienced in breweries probably arise from this, the free sulphur being derived from the hops. Other yeasts are stated to form sulphurous acid in must and wort. Another fact of considerable technical importance is, that the various races of yeast show considerable differences in the amount and proportion of fermentation products other than ethyl alcohol and carbonic acid which they produce. From these remarks it will be clear that to employ the most suitable kind of yeast for a given alcoholic fermentation is of fundamental importance in certain industries. It is beyond the scope of the present article to attempt to describe the different forms of budding fungi (Saccharomyces), mould fungi and bacteria which are capable of fermenting sugar solutions. Thus, six species isolated by Hansen,Saccharomyces cerevisiae,S. PasteurianusI.,1II., III., andS. ellipsoideus, contained invertase and maltase, and can invert and subsequently ferment cane sugar and maltose.S. exiguusandS. Ludwigiicontain only invertase and not maltase, and therefore ferment cane sugar but not maltose.S. apiculatus(a common wine yeast) contains neither of these enzymes, and only ferments solutions of glucose or laevulose.
Previously to Hansen’s work the only way of differentiatingyeasts was by studying morphological differences with the aid of the microscope. Max Reess distinguished the species according to the appearance of the cells thus, the ellipsoidal cells were designatedSaccharomyces ellipsoideus, the sausage-shapedSaccharomyces Pasteurianus, and so on. It was found by Hansen that the same species of yeast can assume different shapes; and it therefore became necessary to determine how the different varieties of yeast could be distinguished with certainty. The formation of spores in yeast (first discovered by T. Schwann in 1839) was studied by Hansen, who found that each species only developed spores between certain definite temperatures. The time taken for spore formation varies greatly; thus, at 52° F.,S. cerevisiaetakes 10,S. PasteurianusI. and II. about 4,S. PasteurianusIII. about 7, andS. ellipsoideusabout 4½ days. The formation of spores is used as an analytical method for determining whether a yeast is contaminated with another species,—for example: a sample of yeast is placed on a gypsum or porcelain block saturated with water; if in ten days at a temperature of 52° F. no spores make their appearance, the yeast in question may be regarded asS. cerevisiae, and not associated withS. PasteurianusorS. ellipsoideus.
The formation of films on fermented liquids is a well-known phenomenon and common to all micro-organisms. A free still surface with a direct access of air are the necessary conditions. Hansen showed that the microscopic appearance of film cells of the same species of Saccharomycetes varies according to the temperature of growth; the limiting temperatures of film formation, as well as the time of its appearance for the different species, also vary.
In the zymo-technical industries the various species of yeast exhibit different actions during fermentations. A well-known instance of this is the “top” and “bottom” brewery fermentations (seeBrewing). In a top fermentation—typical of English breweries—the yeast rises, in a bottom fermentation, as the phrase implies, it settles in the vessel. Sometimes a bottom yeast may for a time exhibit signs of a top fermentation. It has not, however, been possible to transform a typical top yeast into a permanent typical bottom yeast. There appear to be no true distinctive characteristics for these two types. Their selection for a particular purpose depends upon some special quality which they possess; thus for brewing certain essentials are demanded as regards stability, clarification, taste and smell; whereas, in distilleries, the production of alcohol and a high multiplying power in the yeast are required. Culture yeasts have also been successfully employed in the manufacture of wine and cider. By the judicious selection of a type of yeast it is possible to improve the bouquet, and from an inferior must obtain a better wine or cider than would otherwise be produced.
Certain acid fermentations are of common occurrence. TheBacterium acidi lactidescribed by Pasteur decomposes milk sugar into lactic acid.Bacillus amylobacterusually accompanies the lactic acid organism, and decomposes lactic and other higher acids with formation of butyric acid. Moulds have been isolated which occasion the formation of citric acid from glucose. The production of acetic acid from alcohol has received much attention at the hands of investigators, and it has an important technical aspect in the manufacture of vinegar. The phenomenon of nitrification (seeBacteriology,AgricultureandManure),i.e.the formation of nitrites and nitrates from ammonia and its compounds in the soil, was formerly held to be a purely chemical process, until Schloesing and Müntz suggested in 1877 that it was biological. It is now known that the action takes place in two stages; the ammonium salt is first oxidized to the nitrite stage and subsequently to the nitrate.