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diff --git a/old/52824-0.txt b/old/52824-0.txt deleted file mode 100644 index 4150e64..0000000 --- a/old/52824-0.txt +++ /dev/null @@ -1,4151 +0,0 @@ -Project Gutenberg's The Story of a Loaf of Bread, by Thomas Barlow Wood - -This eBook is for the use of anyone anywhere in the United States and most -other parts of the world at no cost and with almost no restrictions -whatsoever. You may copy it, give it away or re-use it under the terms of -the Project Gutenberg License included with this eBook or online at -www.gutenberg.org. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: The Story of a Loaf of Bread - -Author: Thomas Barlow Wood - -Release Date: August 16, 2016 [EBook #52824] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK THE STORY OF A LOAF OF BREAD *** - - - - -Produced by MWS, Wayne Hammond and the Online Distributed -Proofreading Team at http://www.pgdp.net (This file was -produced from images generously made available by The -Internet Archive/American Libraries.) - - - - - - -[Transcriber's Note: - -Italic text delimited by underscores.] - - - - - The Cambridge Manuals of Science and - Literature - - - THE STORY OF A LOAF OF BREAD - - - - - CAMBRIDGE UNIVERSITY PRESS - - London: FETTER LANE, E.C. - - C. F. CLAY, MANAGER - - [Illustration] - - Edinburgh: 100, PRINCES STREET - - London: H. K. LEWIS, 136, GOWER STREET, W.C. - - WILLIAM WESLEY & SON, 28, ESSEX STREET, STRAND - - Berlin: A. ASHER AND CO. - - Leipzig: F. A. BROCKHAUS - - New York: G. P. PUTNAM’S SONS - - Bombay and Calcutta: MACMILLAN AND CO., Ltd. - - - _All rights reserved_ - - - - -[Illustration: - - THE STORY OF - A LOAF OF BREAD - - BY - - T. B. WOOD, M.A. - - Drapers Professor of Agriculture - in the University of Cambridge - - Cambridge: - at the University Press - - New York: - G. P. Putnam’s Sons - - 1913] - - - - - Cambridge: - - PRINTED BY JOHN CLAY, M.A. - AT THE UNIVERSITY PRESS - -_With the exception of the coat of arms at the foot, the design on -the title page is a reproduction of one used by the earliest known -Cambridge printer, John Siberch, 1521_ - - - - -PREFACE - - -I have ventured to write this little book with some diffidence, for it -deals with farming, milling and baking, subjects on which everyone has -his own opinion. In the earlier chapters I have tried to give a brief -sketch of the growing and marketing of wheat. If I have succeeded, the -reader will realise that the farmer’s share in the production of the -staple food of the people is by no means the simple affair it appears -to be. The various operations of farming are so closely interdependent -that even the most complex book-keeping may fail to disentangle the -accounts so as to decide with certainty whether or not any innovation -is profitable. The farmer, especially the small farmer, spends his days -in the open air, and does not feel inclined to indulge in analytical -book-keeping in the evening. Consequently, the onus of demonstrating -the economy of suggested innovations in practice lies with those who -make the suggestions. This is one of the many difficulties which -confronts everyone who sets out to improve agriculture. - -In the third and fourth chapters I have discussed the quality of wheat. -I have tried to describe the investigations which are in progress with -the object of improving wheat from the point of view of both the farmer -and the miller, and to give some account of the success with which they -have been attended. Incidentally I have pointed out the difficulties -which pursue any investigation which involves the cultivation -on the large scale of such a crop as wheat, and the consequent -need of adopting due precautions to ensure accuracy before making -recommendations to the farmer. Advice based on insufficient evidence is -more than likely to be misleading. Every piece of misleading advice is -a definite handicap to the progress of agricultural science. - -The fifth chapter is devoted to a short outline of the milling -industry. In chapter VI the process of baking is described. In the last -two chapters the composition of bread is discussed at some length. I -have tried to state definitely and without bias which points in this -much debated subject are known with some certainty, and which points -require further investigation. - -Throughout the following pages, but especially in chapters III and IV, -I have drawn freely upon the work of my colleagues. I am also much -indebted to my friends, Mr A. E. Humphries, the chairman of the Home -Grown Wheat Committee, and Mr E. S. Beaven of Warminster, whose advice -has always been at my disposal. A list of publications on the various -branches of the subject will be found at the end of the volume. - - T. B. W. - - GONVILLE AND CAIUS COLLEGE, - CAMBRIDGE. - _3 December, 1912._ - - - - -CONTENTS - - - CHAP. PAGE - - Preface v - - I. Wheat-growing 1 - - II. Marketing 15 - - III. The quality of wheat 27 - - IV. The quality of wheat from the miller’s point of view 51 - - V. The milling of wheat 74 - - VI. Baking 91 - - VII. The composition of bread 108 - - VIII. Concerning different kinds of bread 120 - - Bibliography 136 - - Index 139 - - - - -LIST OF ILLUSTRATIONS - - - FIG. PAGE - - 1. Typical ears of wheat 30 - - 2. Bird-proof enclosure for variety testing 34 - - 3. A wheat flower to illustrate the method of cross-fertilising 41 - - 4. Parental types and first and second generation 43 - - 5. Parent varieties in bird-proof enclosure 48 - - 6. Testing new varieties in the field 50 - - 7. Loaves made from Manitoba wheat 54 - - 8. Loaves made from English wheat 54 - - 9. Loaves made from Rivet wheat 55 - - 10. Loaves made from Manitoba wheat, English wheat, and - Manitoba-English hybrid, Burgoyne’s Fife 59 - - 11. Gluten in water and acid 69 - - 12. Gluten in water containing both acid and salts 71 - - 13. End view of break rolls 81 - - 14. Break rolls showing gearing 82 - - 15. Reduction rolls 87 - - 16. Baking test: loaves rising in incubator 92 - - 17. Baking test: loaves leaving the oven 93 - - - - -THE STORY OF A LOAF OF BREAD - - - - -CHAPTER I - -WHEAT GROWING - - -Wheat is one of the most adaptable of plants. It will grow on almost -any kind of soil, and in almost any temperate climate. But the question -which concerns the wheat grower is not whether he can grow wheat, but -whether he can grow it profitably. This is a question of course that -can never receive a final answer. Any increase in the price of wheat, -or any improvement that lowers the cost of cultivation, may enable -growers who cannot succeed under present conditions to grow wheat at -a profit. Thus if the population of the world increases, and wheat -becomes scarce, the wheat-growing area will doubtless be extended -to districts where wheat cannot be grown profitably under present -conditions. A study of the history of wheat-growing in this country -during the last century shows that the reverse of this took place. -In the first half of that period the population had increased, and -from lack of transport facilities and other causes the importation of -foreign wheat was small. Prices were high in consequence and every -acre of available land was under wheat. As transport facilities -increased wheat-growing areas were developed in Canada, in the -Western States of America, in the Argentine, and in Australia, and -the importation of foreign wheat increased enormously. This led to -a rapid decrease in prices, and wheat-growing had to be abandoned -on all but the most suitable soils in the British Isles. From 1880 -onwards thousands of acres of land which had grown wheat profitably -for many years were laid down to grass. In the last decade the world’s -population has increased faster than the wheat-growing area has been -extended. Prices have consequently risen, and the area under wheat in -the British Isles will no doubt increase. - -But although it cannot be stated with finality on what land wheat can -be grown, or cannot be grown, at a profit, nevertheless accumulated -experience has shown that wheat grows best on the heavier kinds of -loam soils where the rainfall is between 20 and 30 inches per annum. -It grows nearly as well on clay soils and on lighter loams, and with -the methods of dry farming followed in the arid regions of the Western -States and Canada, it will succeed with less than its normal amount of -rainfall. - -It is now about a hundred years since chemistry was applied with any -approach to exactitude to questions affecting agriculture; since for -instance it was first definitely recognised that plants must obtain -from their surroundings the carbon, hydrogen, oxygen, nitrogen, -phosphorus, sulphur, potassium, calcium, and other elements of which -their substance is composed. For many years there was naturally much -uncertainty as to the source from which these several elements were -derived. Experiment soon showed that carbon was undoubtedly taken -from the air, and that its source was the carbon dioxide poured into -the air by fires and by the breathing of animals. It soon became -obvious too that plants obtain from the soil water and inorganic salts -containing phosphorus, sulphur, potassium, calcium, and so on; but -for a long time the source of the plants’ supply of nitrogen was not -definitely decided. Four-fifths of the air was known to be nitrogen. -The soil was known to contain a small percentage of that element, which -however amounts to four or five tons per acre. Which was the source -of the plants’ nitrogen could be decided only by careful experiment. -As late as 1840 Liebig, perhaps the greatest chemist of his day, -wrote a book on the application of chemistry to agriculture. In it he -stated that plants could obtain from the air all the nitrogen they -required, and that, to produce a full crop, it was only necessary to -ensure that the soil should provide a sufficient supply of the mineral -elements, as he called them, phosphorus, potassium, calcium, etc. -Now of all the elements which the farmer has to buy for application -to his land as manure, nitrogen is the most costly. At the present -time nitrogen in manures costs sevenpence per pound, whilst a pound -of phosphorus in manures can be bought for fivepence, and a pound -of potassium for twopence. The importance of deciding whether it is -necessary to use nitrogen in manures needs no further comment. It -was to settle definitely questions like this that John Bennet Lawes -began his experiments at his home at Rothamsted, near Harpenden in -Hertfordshire, on the manuring of crops. These experiments were started -almost simultaneously with the publication of Liebig’s book, and many -of Lawes’ original plots laid out over 70 years ago are still in -existence. The results which he obtained in collaboration with his -scientific colleague, Joseph Henry Gilbert, soon overthrew Liebig’s -mineral theory of manuring, and showed that in order to grow full crops -of wheat it is above all things necessary to ensure that the soil -should be able to supply plenty of nitrogen. Thus it was found that the -soil of the Rothamsted Experiment Station was capable of growing wheat -continuously year after year. With no manure the average crop was only -about 13 bushels per acre. The addition of a complete mineral manure -containing phosphorus, calcium, potassium, in fact all the plant wants -from the soil except nitrogen, only increased the crop to 15 bushels -per acre. Manuring with nitrogen on the other hand increased the crop -to 21 bushels per acre. Obviously on the Rothamsted soil wheat has -great difficulty in getting all the nitrogen it wants, but is well -able to fend for itself as regards what Liebig called minerals. This -kind of experiment has been repeated on almost every kind of soil in -the United Kingdom, and it is found that the inability of wheat to -supply itself with nitrogen applies to all soils, except the black -soils of the Fens which contain about ten times more nitrogen than the -ordinary arable soils of the country. It is the richness in nitrogen -of the virgin soils of the Western States and Canada, and of the black -soils of Russia, that forms one of the chief factors in their success -as wheat-growing lands. It must be added, however, that continuous -cropping without manure must in time exhaust the stores of nitrogen in -even the richest soil, and when this time comes the farmers in these -at present favoured regions will undoubtedly find wheat-growing more -costly by whatever sum per acre they may find it necessary to expend -in nitrogenous manure. The world’s demand for nitrogenous manure is -therefore certain to increase. Such considerations as these inspired -Sir William Crookes’ Presidential address to the British Association in -1898, in which he foretold the probability of a nitrogen famine, and -explained how it must lead to a shortage in the world’s wheat supply. -The remedy he suggested was the utilization of water-power to provide -the energy for generating electricity, by means of which the free -nitrogen of the air should be brought into combination in such forms -that it could be used for manure. It is interesting to note that these -suggestions have been put into practice. In Norway, in Germany, and in -America waterfalls have been made to drive dynamos, and the electricity -thus generated has been used to make two new nitrogenous manures, -calcium nitrate and calcium cyanamide, which are now coming on to the -market at prices which will compete with sulphate of ammonia from the -gas works, nitrate of soda from Chili, Peruvian guano, and the various -plant and animal refuse materials which have up to the present supplied -the farmer with his nitrogenous manures. This is welcome news to the -wheat grower, for the price of manurial nitrogen has steadily risen -during the last decade. - -Before leaving the question of manuring one more point from the -Rothamsted experiments must be referred to. It has already been -mentioned that when manured with nitrogen alone the Rothamsted soil -produced 21 bushels of wheat per acre. When, however, a complete manure -containing both nitrogen and minerals was used the crop rose to 35 -bushels per acre which is about the average yield per acre of wheat in -England. This shows that although the yield of wheat is dependent in -the first place on the nitrogen supplied by the soil, it is still far -from independent of a proper supply of minerals. A further experiment -on this point showed that minerals are not used up by the crop to which -they are applied, and that any excess left over remains in the soil -for next year. This is not the case with nitrogenous manures. Whatever -is left over from one crop is washed out of the soil by the winter -rains, and lost. Translated into farm practice these results mean that -nitrogenous manures should be applied direct to the wheat crop, but -that wheat may as a rule be trusted to get all the minerals it wants -from the phosphate and potash applied directly to other crops which are -specially dependent on an abundant supply of these substances. - -At Rothamsted, Lawes and Gilbert adopted the practice of growing wheat -continuously on the same land year after year in order to find out -as quickly as possible the manurial peculiarities of the crop. This -however is not the general system of the British farmer, but it has -been carried out with commercial success by Mr Prout of Sawbridgeworth -in Hertfordshire. The Sawbridgeworth farm is heavy land on the London -clay. Mr Prout’s system was to cultivate the land by steam power, to -manure on the lines suggested by the Rothamsted experiments, and to -sell both grain and straw. Wheat was grown continuously year after year -until the soil became infested with weeds, when some kind of root crop -was grown to give an opportunity to clean the land. A root crop is not -sown until June so that the land is bare for cleaning all the spring -and early summer. Such crops also are grown in rows two feet or more -apart, and cultural implements can be used between the rows of plants -until the latter cover the soil by the end of July or August. After -cleaning the land in this way the roots are removed from the land in -the winter and used to feed the stock. By this time it is too late to -sow wheat, so a barley crop is sown the following spring, and with the -barley clover is sown. Clover is an exception to the rule that crops -must get their nitrogen from the soil. - -On the roots of clover, and other plants of the same botanical order, -such as lucerne, sainfoin, beans and peas, many small swellings are -to be found. These swellings, or nodules as they are usually called, -are produced by bacteria which possess the power of abstracting free -nitrogen from the air and transforming it into combined nitrogen in -such a form that the clover or other host-plant can feed on it. The -clover and the bacteria live in Symbiosis, or in other words in a -kind of mutual partnership. The host provides the bacteria with a -home and allows them to feed on the sugar and other food substances -in its juices, and they in return manufacture nitrogen for the use of -the host. When the clover is cut for hay, its roots are left in the -soil, and in them is a large store of nitrogen derived from the air. -A clover crop thus enriches the soil in nitrogen and is the best of -all preparations for wheat-growing. After the clover, wheat was grown -again year after year until it once more became necessary to clean the -land. This system of wheat-growing was carried on at Sawbridgeworth -for many years with commercial success. It never spread through the -country because its success depends on the possibility of finding -a remunerative market for the straw. The bulk of straw is so great -compared with its price that it cannot profitably be carried to any -considerable distance. The only market for straw in quantity is a -large town, and there is no considerable area of land suitable for -wheat-growing near a sufficiently large town to provide a market for -the large output of straw which would result from such a system of -farming. - -The ordinary practice of the British farmer is to grow his wheat in -rotation with other crops. Various rotations are practised to suit the -special circumstances of different districts, one might almost say of -special farms. This short account of wheat-growing does not profess to -give a complete account of even English farming practice. It is only -necessary to describe here one rotation in order to give a general -idea of the advantages of that form of husbandry. For this purpose -it will suffice to describe the Norfolk or four course rotation. This -rotation begins with a root crop, usually Swede turnips, manured with -phosphates, and potash too on the lighter lands. This crop, as already -described, provides the opportunity of cleaning the land. It produces -also a large amount of food for sheep and cattle. Part of the roots are -left on the land where they are eaten by sheep during the winter. The -roots alone are not suitable for a complete diet. They are supplemented -by hay and by some kind of concentrated food rich in nitrogen, usually -linseed cake, the residue left when the oil is pressed from linseed. -Now an animal only retains in its body about one-tenth of the nitrogen -of its diet, so that nine-tenths of the nitrogen of the roots, hay -and cake consumed by the sheep find their way back to the land. This -practice of feeding sheep on the land therefore acts practically as -a liberal nitrogenous manuring. The trampling of the soil in a wet -condition in the winter also packs its particles closely together, and -increases its water-holding power, in much the same way as the special -cultural methods employed in the arid western States under the name -of dry farming. The rest of the roots are carted to the homestead for -feeding cattle, usually fattening cattle for beef. Again the roots are -supplemented by hay, straw, and cake of some kind rich in nitrogen. -The straw from former crops is used for litter. Its tubular structure -enables it to soak up the excreta of the animals, so that the farmyard -manure thus produced retains a large proportion of the nitrogen, and -other substances of manurial value, which the animals fail to retain in -their bodies. This farmyard manure is kept for future use as will be -seen later. - -As soon as the sheep have finished eating their share of the turnips -they are sold for mutton. It is now too late in the season to sow -wheat. The land is ploughed, but the ploughing is only a shallow one, -so that the water stored in the deeper layers of the soil which have -been solidified by the trampling of the sheep may not be disturbed. The -surface soil turned up by the plough is pulverised by harrowing until -a fine seed-bed is obtained, and barley is sown early in the spring. -Clover and grass seeds are sown amongst the barley, so that they may -take firm root whilst the barley is growing and ripening. The barley -is harvested in the autumn. The young clover and grasses establish -themselves during the autumn and winter, and produce a crop of hay the -following summer. This is harvested towards the end of June, and the -aftermath forms excellent autumn grazing for the sheep and cattle which -are to be fed the next winter. - -As soon as harvest is over the farmer hopes for rain to soften the -old clover land, or olland as it is called in Norfolk, so that he can -plough it for wheat sowing. Whilst he is waiting for rain he takes -advantage of the solidity of the soil, produced by the trampling of the -stock, to cart on to the olland the farmyard manure produced during -the cattle feeding of the last winter. As soon as the rain comes this -is ploughed in, and the seed-bed for the wheat prepared as quickly -as possible. Wheat should be sown as soon as may be after the end of -September, so that the young plant may come up and establish itself, -while the soil is yet warm from the summer sun, and before the winter -frosts set in. The wheat spends the winter in root development, and -does not make much show above ground until the spring. It is harvested -usually some time in August. The wheat stubble is ploughed in the -autumn and again in the spring, and between then and June, when the -roots are sown, it undergoes a thorough cleaning. - -The complete rotation has now been described. It remains only to point -out some of its numerous advantages. In the first place the system -described provides excellent conditions for growing both wheat and -barley in districts where the rainfall is inclined to be deficient, -say from 20 to 25 inches per annum, as it is in the eastern counties, -and on the Yorkshire wolds. Not only is an abundant supply of nitrogen -provided for these crops through the medium of the cake purchased for -the stock, but the solidification of the deeper layers of the soil -ensures the retention of the winter’s rain for the use of the crop -during the dry summer. The residue of the phosphates and potash applied -to the root crop, and left in the soil when that crop is removed, -provides for the mineral requirements of the barley and the wheat. -Thus each crop gets a direct application of the kind of manure it most -needs. Rotation husbandry also distributes the labour of the farm over -the year. After harvest the farmyard manure is carted on to the land. -This is followed by wheat sowing. In the winter there is the stock to -be fed. The spring brings barley sowing, the early summer the cleaning -of the land for the roots. Then follow the hay harvest and the hoeing -of the roots, and by this time corn-harvest comes round once again. - -It must not be forgotten that each crop the farmer grows is subject to -its own pests. On a four course rotation each crop comes on the same -field only once in four years. Whilst the field is under roots, barley, -and clover, the wheat pests are more or less starved for want of food, -and their virulence is thereby greatly diminished. The catalogue of -the advantages of rotation of crops is a long one but one more must be -mentioned. The variety of products turned out for sale by the rotation -farmer ensures him against the danger which pursues the man who puts -all his eggs in one basket. The four course farmer produces not only -wheat and barley, but beef and mutton. The fluctuations in price of -these products tend to compensate each other. When corn is cheap, -meat may be dear, and vice versâ. Thus in the years about 1900, when -corn was making very low prices, sheep sold well, and the profit on -sheep-feeding enabled many four course farmers to weather the bad times. - -The system of wheat-growing above described is an intensive one. -The cultivation is thorough, the soil is kept in good condition by -manuring, or by the use of purchased feeding stuffs, and the cost of -production is comparatively high. Such systems of intensive culture -prevail in the more densely populated countries, but the bulk of the -world’s wheat supply is grown in thinly populated countries, where -the methods of cultivation are extensive. Wheat is sown year after -year on the same land, no manure is used, and tillage is reduced to a -minimum. This style of cultivation gradually exhausts the fertility of -the richest virgin soil, and its cropping capacity falls off. As soon -as the crop falls below a certain level it ceases to be profitable. No -doubt the fertility of the exhausted soil could be restored by suitable -cultivation and manuring, but it is usually the custom to move towards -districts which are still unsettled, and to take up more virgin soil. -Thus the centre of the area of wheat production in the States has moved -nearly 700 miles westward in the last 50 years. - - - - -CHAPTER II - -MARKETING - - -In the last chapter we have followed the growing of the wheat from -seed time to harvest. But when the farmer has harvested his corn his -troubles are by no means over. He has still to thrash it, dress it, -sell it, and deliver it to the mill or to the railway station. In the -good old times a hundred years ago thrashing was done by the flail, -and found work during the winter for many skilled labourers. This -time-consuming method has long disappeared. In this country all the -corn is now thrashed by machines, driven as a rule by steam, but still -in some places by horse-gearing. The thrashing machine, like all other -labour saving devices, when first introduced was bitterly opposed by -the labourers, who feared that they might lose their winter occupation -and the wages it brought them. In the life of Coke of Norfolk, the -first Lord Leicester, there is a graphic account of the riots which -took place when the first thrashing machine was brought into that -county. - -Only the larger farmers possess their own machines. The thrashing on -the smaller farms is done by machines belonging to firms of engineers, -which travel the country, each with its own team of men. These -machines will thrash out more than 100 bags of wheat or barley in a -working day. The more modern machines dress the corn so that it is -ready for sale without further treatment. After it is thrashed the -wheat is carried in sacks into the barn and poured on to the barn -floor. It is next winnowed or dressed, again by a machine, which -subjects it to a process of sifting and blowing in order to remove -chaff, weed-seeds and dirt. As it comes from the dressing machine it is -measured into bags, each of which is weighed and made up to a standard -weight ready for delivery. In the meantime the farmer has taken a -sample of the wheat to market. The selling of wheat takes place on -market day in the corn hall, or exchange, with which each market town -of any importance is provided. In the hall each corn merchant in the -district rents a small table or desk, at which he stands during the -hour of the market. The farmer takes his sample from one merchant to -another and sells it to the man who offers him the highest price. The -merchant keeps the sample and the farmer must deliver wheat of like -quality. In the western counties it is sometimes customary for the -farmers to take their stand near their sample bags of corn whilst the -merchants walk round and make their bids. - -But unfortunately it too often happens that the struggling farmer -cannot have a free hand in marketing his corn. In many cases he must -sell at once after harvest to raise the necessary cash to buy stock -for the winter’s feeding. This causes a glut of wheat on the market -in the early autumn, and the price at once drops. In other cases the -farmer has bought on credit last winter’s feeding stuffs, or last -spring’s manures, and is bound to sell his wheat to the merchant in -whose debt he finds himself, and to take the best price offered in a -non-competitive market. - -These are by no means all the handicaps of the farmer who would market -his corn to the best advantage. Even the man who is blessed with plenty -of ready money, and can abide his own time for selling his wheat, is -hampered by the cumbrous weights and measures in use in this country, -and above all by their lack of uniformity. In East Anglia wheat is sold -by the coomb of four bushels. By common acceptance however the coomb -has ceased to be four measured bushels, and is always taken to mean 18 -stones or 2¼ cwt. This custom is based on the fact that a bushel of -wheat weighs on the average 63 pounds, and four times 63 pounds makes -18 stones. But this custom is quite local. In other districts the unit -of measure for the sale of wheat is the load, which in Yorkshire means -three bushels, in Oxfordshire and Gloucestershire 40 bushels, and in -parts of Lancashire 144 quarts. Another unit is the boll, which varies -from three bushels in the Durham district to six bushels at Berwick. -It will be noted that most of the common units are multiples of the -bushel, and it might be imagined that this would make their mutual -relations easy to calculate. This however is not so, for in some cases -it is still customary to regard a bushel as a measure of volume and to -disregard the variation in weight. In other cases the bushel, as in -East Anglia, means so many pounds, but unfortunately not always the -same number. Thus the East Anglian bushel is 63 pounds, the London -bushel on Mark Lane Market is the same, the Birmingham bushel is only -62 pounds, the Liverpool and Manchester bushel 70 pounds, the Salop -bushel 75 pounds, and in South Wales the bushel is 80 pounds. Finally, -wheat is sold in Ireland by the barrel of 280 pounds, on Mark Lane by -the quarter of eight bushels of 63 pounds, imported wheat in Liverpool -and Manchester by the cental of 100 pounds, and the official market -returns issued by the Board of Agriculture are made in bushels of 60 -pounds. There is, however, a growing tendency to adopt throughout the -country the 63 pound bushel or some multiple thereof, for example the -coomb or quarter, as the general unit, and the use of the old-fashioned -measures is fast disappearing. - -The farmer of course knows the weights and measures in use in his own -and neighbouring markets, but unless he takes the trouble to look -up in a book of reference the unit by which wheat is sold at other -markets, and to make a calculation from that unit into the unit in -which he is accustomed to sell, the market quotations in the newspapers -are of little use to him in enabling him to follow the fluctuations -of the price of wheat. Thus a Norfolk farmer who wishes to interpret -the information that the price of the grade of wheat known as No. 4 -Manitoba on the Liverpool market is 7/3½, must first ascertain that -wheat is sold at Liverpool by the cental of 100 pounds. To convert -the Liverpool price into price per coomb, the unit in which he is -accustomed to sell, he must multiply the price per cental by 252, the -number of pounds in a coomb of wheat, and divide the result by 100, the -number of pounds in a cental; thus: - - 7/3½ x 252 ÷ 100 = 18/4½. - -It is evident that the farmer who wishes to follow wheat prices in -order to catch the best market for his wheat, must acquaint himself -with an extremely complicated system of weights and measures, and -continually make troublesome calculations. The average English farmer -is an excellent craftsman. He is unsurpassed, indeed one may safely say -unequalled, as a cultivator of the land, as a grower of crops, and as -a breeder and feeder of stock, but like most people who lead open-air -lives, he is not addicted to spending his evenings in arithmetical -calculations. The corn merchant, whose business it is to attend to -such matters, is therefore at a distinct advantage, and the farmer -loses the benefit of a rise in the market until the information slowly -filters through to him. No doubt the time will come, when not only -wheat selling, but all business in this country, will be simplified by -the compulsory enactment of sale by uniform weight. The change from -the present haphazard system or want of system would no doubt cause -considerable temporary dislocation of business, and would abolish many -ancient weights and measures, interesting to the historian and the -archaeologist in their relations to ancient customs, but in the long -run it could not but expedite business, and remove one of the many -handicaps attaching to the isolated position of the farmer. - -Having sold his wheat the farmer now puts it up in sacks of the -standard of weight or measure prevailing in his district. If the -merchant who bought it happens to be also a miller, as is frequently -the case, the wheat is delivered to the mill. Otherwise it is sent -to the railway station to the order of the merchant who bought -it. Meantime the merchant has probably sold it to a miller in a -neighbouring large town, to whom he directs the railway company to -forward it. Thus the wheat directly or indirectly finds its way to a -mill, where it will be mixed with other wheats and ground into flour. - -We have now followed wheat production in England from the ground to -the mill. But at the present time home grown wheat can provide only -about one-fifth of the bread-stuffs consumed by the population of -the United Kingdom, and any account of the growing of wheat cannot -be complete without some mention of the methods employed in other -countries. The extensive methods of wheat-growing in the more thinly -populated countries have already been shortly mentioned. But though -their methods of production are of the simplest, the arrangements for -marketing their produce are far more advanced in organisation than -those already described for the marketing of home grown produce. - -For thrashing in Canada and the Western States, travelling machines -are commonly used, but they are larger than the machines in use in -this country, and the men who travel with them work harder and for -longer hours. It is usual for a Canadian travelling “outfit” to thrash -1000 bags of wheat in a day, about ten times as much as is considered -a day’s thrashing in England. Harvesting and thrashing machinery has -evolved to an extraordinary extent in the West on labour saving lines. -On the Bonanza farms of the Western States machines are in use which -cut off the heads of the wheat, thrash out the seed, and bag it ready -for delivery, as they travel round and round the field. Such machines -of course leave the straw standing where it grew, and there it is -subsequently burnt. Since wheat is grown every year, few animals are -kept beyond the working horses. Very little straw suffices for them and -the rest has no value since its great bulk prohibits its profitable -carriage to a distance. - -After being thrashed the grain is delivered, usually in very large -loads drawn by large teams of horses, to the nearest railway station, -whence it is despatched to the nearest centre where there is a grain -store, or elevator as it is called. Here it is sampled by inspectors -under the control, either of the Government or the Board of Trade, as -the committee is called which manages the wheat exchange at Chicago -or other of the great wheat trading centres. The inspectors examine -the sample, and on the result of their examination, assign the wheat -to one or other of a definite series of grades. These grades are -accurately defined by general agreement of the Board of Trade or by -the Government. Each delivery of wheat is kept separate for a certain -number of days after it has been graded, in case the owner wishes to -appeal against the verdict of the inspector. Such appeals are allowed -on the owner forfeiting one dollar per car load of grain if the verdict -of the inspector is found to have been correct. At the Chicago wheat -exchange 27 grades of wheat are recognised. The following examples show -the methods by which they are defined. The definitions are the subject -of frequent controversy. - -No. 1 Northern Hard Spring Wheat shall be sound, bright, sweet, clean, -and shall consist of over 50 per cent. of hard Scotch Fife, and weigh -not less than 58 pounds to the measured bushel. - -No. 1 Northern Spring Wheat shall be sound, sweet and clean; may -consist of hard and soft varieties of spring wheat, but must contain -a larger proportion of the hard varieties, and weigh not less than 57 -pounds to the measured bushel. - -No. 2 Northern Spring Wheat shall be spring wheat not clean enough or -sound enough for No. 1, but of good milling quality, and must not weigh -less than 56 pounds to the measured bushel. - -No. 3 Northern Spring Wheat shall be composed of inferior shrunken -spring wheat, and weigh not less than 54 pounds to the measured bushel. - -No. 4 Northern Spring Wheat shall include all inferior spring wheat -that is badly shrunken or damaged, and shall weigh not less than 49 -pounds to the measured bushel. - -When sampling wheat for grading, the inspectors also estimate the -number of pounds of impurities per bushel, a deduction for which is -made under the name of dockage. At the same time the weight of wheat in -each car is officially determined. All these points, grade, dockage, -and weight, are officially registered, and as soon as the time has -elapsed for dealing with any appeal which may arise, the wheat is -mixed with all the other wheats of the same grade which may be at -the depot, an official receipt for so many bushels of such and such a -grade of wheat subject to so much dockage being given to the seller or -his agent. These official receipts are as good as cash, and the farmer -can realise cash on them at once by paying them into his bank, without -waiting for the wheat to be sold. - -As each delivery of wheat is graded and weighed, word is sent to -the central wheat exchanges that so many bushels of such and such -grades are at the elevator, and official samples are also sent on -at the same time. The bulk of the sales however are made by grade -and not by sample. The actual buying and selling takes place in the -wheat exchanges, or wheat pits as they are called, at Chicago, New -York, Minneapolis, Duluth, Kansas City, St Louis, and Winnipeg, each -of which markets possesses its own special character. Chicago the -greatest of the wheat markets of the world passes through its hands -every year about 25 million bushels of wheat, chiefly from the western -and south-western States. It owes its preeminence to the converging -railway lines from those States, and to its proximity to Lake Michigan -which puts it in touch with water carriage. New York has grown in -importance as a wheat market since the opening of the Erie Canal. It -is especially the market for export. Minneapolis is above all things -a milling centre. No doubt it has become so partly on account of the -immense water-power provided by the Falls of St Antony. It receives -annually nearly 100 million bushels of wheat, its speciality being the -various grades of hard spring wheat. Duluth is the most northern of the -American wheat markets. It receives and stores over 50 million bushels -annually. It owes its importance to its position on Lake Superior, -which is available for water carriage. Kansas City deals with over 40 -million bushels per annum, largely hard winter wheat, which it ships -down the Missouri River. St Louis deals in soft winter wheats to the -extent of about 20 million bushels per annum. Winnipeg is the market -for Canadian wheats, to the extent of over 50 million bushels per -annum. It has the advantage of two navigable rivers, the Red River and -the Assiniboine, and it is also a great railway centre. Its importance -is increasing as the centre of the wheat-growing area moves to the -north and west, and it is rapidly taking the leading position in the -wheat markets of the world. - -It has been stated above that Chicago is the greatest wheat market, -but it will no doubt have been noticed that this is not borne out by -the figures which have been quoted. For instance, Minneapolis receives -every year nearly four times as much wheat as Chicago. The reason of -this apparent discrepancy is that the sales at Minneapolis are really -_bona fide_ sales of actual wheat for milling, whilst nine-tenths -of the sales at Chicago are not sales of actual wheat, but of what -are known as “futures.” On this assumption, whilst the actual wheat -received at Chicago is 25 million bushels, the sales amount to 250 -million bushels. Such dealing in futures takes place to a greater or -less extent at all the great wheat markets, but more at Chicago than -elsewhere. - -The primary reason for dealing in futures is that the merchant who -buys a large quantity of wheat, which he intends to sell again at some -future time, may be able to insure himself against loss by a fall -in price whilst he is holding the wheat he has bought. This he does -by selling to a speculative buyer an equal quantity of wheat to be -delivered at some future time. If whilst he is holding his wheat prices -decline, he will then be able to recoup his loss on the wheat by buying -on the market at the reduced price now current to meet his contract -with the speculative buyer, and the profit he makes on this transaction -will more or less cover his loss on the actual deal in wheat which -he has in progress. As a matter of fact he does not actually deliver -the wheat sold to the speculative buyer. The transaction is usually -completed by the speculator paying to the merchant the difference in -value between the price at which the wheat was sold and the price to -which it has fallen in the interval. This payment is insured by the -speculative buyer depositing a margin of so many cents per bushel at -the time when the transaction was made. Speculation is, however, kept -within reasonable bounds by the fact that a seller may always be called -upon to deliver wheat instead of paying differences. - -The advantage claimed for this system of insurance is that whilst -it is not more costly to the dealers in actual wheat than any other -equally efficient method, it supports a number of speculative buyers -and sellers, whose business it is to keep themselves in touch with -every phase of the world’s wheat supply. The presence of such a body of -men whose wits are trained by experience of market movements, and who -are ready at any moment to back their judgment by buying and selling -large quantities of wheat for future delivery, is considered to exert -a steadying effect on the price of wheat, and to lessen the extent of -fluctuations in the price. - - - - -CHAPTER III - -THE QUALITY OF WHEAT - - -In discussing the quality of wheat it is necessary to adopt two -distinct points of view, that of the farmer and that of the miller. A -good wheat from the farmer’s point, of view is one that will year by -year give him a good monetary return per acre. Now the monetary return -obviously depends on two factors, the yield per acre and the value per -quarter, coomb, or bushel, as the case may be. These two factors are -quite independent and must be discussed separately. - -We will first confine our attention to the yield per acre. This has -already been shown to depend on the presence in the soil of plenty of -the various elements required by plants, in the case of wheat nitrogen -being especially important. The need of suitable soil and proper -cultivation has also been emphasised. These conditions are to a great -extent under the control of the farmer, whose fault it is if they -are not efficiently arranged. But there are other factors affecting -the yield of wheat which cannot be controlled, such for instance as -sunshine and rainfall. The variations in these conditions from year to -year are little understood, but they are now the subject of accurate -study, and already Dr W. N. Shaw, the chief of the Meteorological -Office has suggested a periodicity in the yield of wheat, connected -with certain climatic conditions, notably the autumnal rainfall. - -We have left to the last one of the most important factors which -determine the yield of wheat, namely, the choice of the particular -variety which is sown. This is undoubtedly one of the most important -points in wheat-growing which the farmer has to decide for himself. -The British farmer has no equal as a producer of high class stock. He -supplies pedigree animals of all kinds to the farmers of all other -lands, and he has attained this preeminence by careful attention to -the great, indeed the surpassing, importance of purity of breed. It -is only in recent years that the idea has dawned on the agricultural -community that breed is just as important in plants as in animals. It -is extraordinary that such an obvious fact should have been ignored -for so long. That it now occupies so prominently the attention of the -farmers is due to the work of the agricultural colleges and experiment -stations in Sweden, America, and many other countries, and last but -by no means least in Great Britain. This demonstration of the value -of plant breeding is perhaps the greatest achievement in the domain -of agricultural science since the publication of Lawes and Gilbert’s -classical papers on the manurial requirements of crops. - -Wheat is not only one of the most adaptable of plants. It is also one -of the most plastic and prone to variation. During the many centuries -over which its cultivation has extended it has yielded hundreds of -different varieties, whose origin, however, except in a few doubtful -cases is unknown. Comparatively few of these varieties are in common -use in this country, and even of these it was impossible until recently -to say which was the best. It was even almost impossible to obtain -a pure stock of many of the standard varieties. This is by no means -the simple matter it appears to be. It is of course quite easy to pick -out a single ear, to rub out the grain from it, to sow the grain on a -small plot by itself and to raise a pound or so of perfectly pure seed. -This can again be sown by itself, and the produce, thrashed by hand, -will give perhaps a bushel of seed which will be quite pure. From this -seed it will be possible to sow something like an acre; and now the -trouble begins. Any kind of hand thrashing is extremely tedious for the -produce of acre plots, and thrashing by machinery becomes imperative. -Now a thrashing machine is an extremely complicated piece of apparatus, -which it is practically impossible thoroughly to clean. When once seed -has been through such a machine it is impossible to guarantee its -purity. Contamination in the thrashing machine is usually the cause of -the impurity of the stocks of wheat and other cereals throughout the -country. The only remedy is for the farmer to renew his stock from time -to time from one or other of the seedsmen or institutions who make it -their business to keep on hand pure stocks obtained by the method above -described. - -[Illustration: Fig. 1. Typical ears of a few of the many cultivated -varieties of wheat] - -Comparative trials of pure stocks of many of the standard varieties -of wheat, and of the other cereals, are being carried out in almost -every county by members of the staff of the agricultural colleges. -The object of such trials is to determine the relative cropping power -of the different varieties. This might at first sight appear to be -an extremely simple matter, but a moment’s consideration shows that -this is not the case. No soil is so uniform that an experimenter can -guarantee that each of the varieties he is trying has the same chance -of making a good yield as far as soil is concerned. It is a matter of -common knowledge too that every crop of wheat is more or less affected -by insect and fungoid pests, whose injuries are unlikely to fall -equally on each of the varieties in any variety test. Many other causes -of variation, such as unequal distribution of manure, inequalities in -previous cropping of the land, irregular damage by birds, may well -interfere with the reliability of such field tests. - -Much attention has been given to this subject during the last few -years, and it has been shown that as often as not two plots of the -same variety of wheat grown in the same field under conditions which -are made as uniform as possible will differ in yield by 5 per cent. or -more. Obviously it is impossible to make comparisons of the cropping -power of different varieties of wheat as the result of trials in -which single plots of each variety are grown. It is a deplorable fact -however that the results of most of the trials which are published are -based on single plots only of the varieties compared. Such results -can have no claim to reliability. Single plots tests are excellent -as local demonstrations, to give the farmers a chance of seeing the -general characters of the various wheats in the field, but for the -determination of cropping power their results are misleading. For -the comparison of two varieties however an accuracy of about 1 per -cent., which is good enough for the purpose in view, can be obtained -by growing, harvesting and weighing separately, five separate plots of -each variety under experiment, provided the plots are distributed in -pairs over the experimental field. - -Still greater accuracy can be attained by growing very large numbers -of very small plots of each variety in a bird-proof enclosure. The -illustration shows such an enclosure at Cambridge where five varieties -were tested, each on 40 plots. Each plot was one square yard, and the -whole 200 plots occupied so small an area that uniformity of soil could -be secured by hand culture. - -Several experimenters are now at work on these lines, and it is to be -hoped that all who wish to carry out variety tests will either follow -suit, or content themselves with using their single plots only for -demonstrating the general characters of the varieties in the field. - -So far we have confined our discussion to the standard varieties, and -we must now turn our attention to the work which has been done in -recent years on the breeding of new varieties which will yield heavier -crops than any of the varieties hitherto in cultivation. - -[Illustration: Fig. 2. Part of bird-proof enclosure containing many -small plots for variety testing] - -It is impossible to give more than a very brief outline of the vast -amount of work which has been done on this subject. Broadly speaking, -two methods have been used, selection and hybridisation. Of these -selection is the simpler, but even selection is by no means the simple -matter it might appear to be. Let us examine for a moment the various -characters of a single wheat plant which determine its capacity for -yielding grain. The average weight of one grain, the number of grains -in an ear, the number of ears on the plant, are obviously all of them -characters which will influence the weight of grain yielded by the -plant. Many experimenters have examined thousands of plants for these -characters, often by means of extremely ingenious mechanical sorting -instruments, and have raised strains of seed from the plants showing -one or more of these characters in the highest degree. The results of -this method of selection have as a rule been unsuccessful, no doubt -because the size of the grain, the number of grains in the ear, and -the number of ears on the plant, are so largely determined by the food -supply, or by some other cause quite outside the plant itself. They are -in fact in most cases acquired characters, and are not inherited. This -method of selection results in picking out rather the well nourished -plant than the well bred one. Again it is obvious that the weight of -grain per acre is measured by the weight of one grain, multiplied by -the number of grains per ear, multiplied by the number of ears per -plant, multiplied by the number of plants per acre. Selecting for any -one of these characters, say large ears, is quite likely to diminish -other equally important characters, say number of ears per plant. - -In order to avoid these difficulties the method of selection according -to progeny has been devised. The essence of this method is to select -for stock, not the best individual plant, but the plant whose progeny -yields the greatest weight of seed per unit area. This method was -applied with great industry and some success in the Minnesota wheat -breeding experiments of Willett Hays. Large numbers of promising plants -were collected from a plot of the best variety in that district. The -seed from each plant was rubbed out and sown separately. One hundred -seeds from each plant were sown on small separate plots which were -carefully marked out and labelled. Every possible precaution was taken -to make all the little plots uniform in every way. By harvesting each -plot separately, and weighing the grain it produced, it was possible to -find out which of the original plants had given the largest yield. This -process was repeated by sowing again on separate plots a hundred seeds -from each individual plant from the best plot, and again weighing the -produce of each plot. After several repetitions it was stated that new -strains were obtained which yielded considerably greater crops than the -variety from which they were originally selected. These results were -published in 1895, but no definite statements have since appeared as to -the success ultimately attained. - -This method of selection is undoubtedly more likely to give successful -results than the method which depends on the selection of plants for -their apparent good qualities; but it has several weak points. In -the first place it is almost impossible to make the soil of a large -number of plots so uniform that variation in yield due to varying soil -conditions will not mask the variations due to the different cropping -power of the seed of the separate plants. Many experimenters are still -at work with a view to overcome this difficulty. Secondly, plant -breeders are by no means agreed on the exact theoretical meaning of -improvement by selection. The balance of evidence at the present time -seems to tend towards the general adoption of what is known as the -pure-line theory. According to this theory, which was first enunciated -by Johannsen of Copenhagen as the outcome of a lengthy series of -experiments with beans, the general population of plants, in say a -field of wheat of one of the standard varieties giving an average -yield of say 40 bushels per acre, consists of a very large number of -races each varying in yielding capacity from say 30 to 50 bushels per -acre. These races can be separated by collecting a very large number -of separate plants, sowing say 100 seeds from each on a separate plot, -and weighing the produce separately. The crop on each plot, being the -produce of a separate plant, will be a distinct race, or pure line -as it is called, and each pure line will possess a definite yielding -power of its own. If this is so the difficulty of soil variation can be -overcome by saving seed from many of the best plots, and sowing it on -several separate plots. At harvest time these are gathered separately -and weighed. By averaging the weights of grain from many separate plots -scattered over the experimental area the effect of soil variation can -be eliminated. - -The method is very laborious, but seems to promise successful results. -For instance, Beaven of Warminster, working on these lines, has -succeeded in isolating a pure line of Archer barley which is a distinct -advance on the ordinary stocks of that variety. There appears to be -no reason why it should not be applied to wheat with equal success; -in fact, Percival of Reading states that his selected Blue Cone wheat -was produced in this way. The essence, of the method is that if the -pure-line theory holds there is no necessity to continue selecting -the best individual plant from each plot, for each plot being the -produce of a single plant must be a pure line with its own definite -characters. The whole of the seed from a number of the best plots can -therefore be saved. The seed from each of these good plots can be used -to sow many separate plots: by averaging the yields from these plots -the effects of soil variation can be eliminated, and the cropping -power thus determined with great accuracy. It is thus possible to -pick out the best pure line with far greater certainty than in any -other way. It must not be forgotten, however, that the success of the -method depends on the truth of the pure-line theory. It should also -be pointed out that the cereals are all self-fertilised plants. When -working on these lines with plants which are readily cross-fertilised, -such for instance as turnips or mangels, it is necessary to enclose the -original individual plants, and the subsequent separate plots, so as to -prevent them from crossing with plants of other lines, in which case -the progeny would be cross-bred and not the progeny of a single plant. -This of course enormously increases the difficulty of carrying out the -experiment. Enough has been said to show that the task of improving -plants by systematic selection is an extremely tedious and difficult -one. Of course anyone may be fortunate enough to drop on a valuable -sport when carefully inspecting his crops, and it appears likely that -many of the most valuable varieties in cultivation have originated from -lucky chances of this kind. - -It has always been the dream of the plant breeder to make use of the -process of hybridisation for creating new varieties, but until the -work of Mendel threw new light on the subject the odds were against -the success of the breeder. The idea of the older hybridisers was that -crossing two dissimilar varieties broke the type and gave rise to -greatly increased variation. From the very diverse progeny resulting -from the cross, likely individuals were picked out. Seed was saved from -these and sown on separate plots, and attempts were made to obtain a -fixed type by destroying, or roguing as it is called, all the plants -which departed from the desired type. This was a tedious process which -seldom resulted in success. Mendel’s discoveries, made originally -nearly 50 years ago, as the result of experiments in the garden of -his monastery, in the crossing of different varieties of garden peas, -remained unknown until rediscovered in 1899. In the 12 years which -have elapsed since that date the results which have been achieved show -clearly that the application of Mendelian methods is likely greatly -to increase the simplicity and the certainty of plant improvement by -hybridisation. - -[Illustration: Fig. 3. A wheat flower with the chaff opened to show the -stamens and the stigmas] - -Perhaps the best way of describing the bearing of Mendel’s Laws on the -improvement of wheat is to give an illustration from the work carried -out by Biffen at Cambridge, dealing at first with simple characters -obvious to anyone. In one of his first experiments two varieties of -wheat were crossed with each other. The one variety possessed long -loose beardless ears, the other short dense bearded ears. The crossing -was performed early in June, sometime before what the farmer calls -flowering time. The flowering of wheat as understood by the farmer -is the escape of the stamens from the flower. Fertilisation always -takes place before this, and crossing must be done of course before -self-fertilisation has been effected. The actual crossing is done -thus: An ear of one of the varieties having been chosen, one of the -flowers is exposed by opening the chaff which encloses it (Fig. 3), -the stamens are removed by forceps, and a stamen from a flower of the -other variety is inserted, care being taken that it bursts so that -the pollen may touch the feathery stigmas. The chaff is then pushed -back so that it may protect the flower from injury. The pollen grains -grow on the stigmas, and penetrate down the styles into the ovary. In -this way cross-fertilisation is effected. It is usual to operate on -several flowers on an ear in this way, and to remove the other flowers, -so that no mistake may be made as to which seed is the result of the -cross. Immediately after the operation the ear is usually tied up in -a waxed paper bag. This serves to make it absolutely certain that -no other pollen can get access to the stigmas except that which was -placed there. At the same time it is a convenient way of marking the -ear which was experimented upon. The cross is usually made both ways, -each variety being used both as pollen parent and as ovary parent. -As soon as the cross-fertilised seeds are ripe they are gathered, and -early in the autumn they are sown. It is almost necessary to sow them -and other small quantities of seed wheat in an enclosure protected by -wire netting. Otherwise they are very liable to suffer great damage -from sparrows. The plants which grow from the cross-fertilised seeds -are known as the first generation. In the case under consideration, -they were found to produce ears of medium length and denseness, -intermediate between the ears of the two parent varieties, and to be -beardless. The first generation plants were also characterised by -extraordinary vigour, as is the case with almost all first crosses, -both in plants and animals. Their seed was saved and sown on a small -plot, and produced some hundreds of plants of the second generation. -On examining these second generation plants it was found that the -characters of the parent varieties had rearranged themselves in every -possible combination, long ears with and without beard, short ears with -and without beard, intermediate ears with and without beard, as shown -in Fig. 4. These different types were sorted out and counted, when they -were found to be present in perfectly definite proportions. This is -best shown in the form of a tabulated statement, thus: - - Ears Ears Ears Ears Ears Ears - Long Long Medium Medium Short Short - Beardless Bearded Beardless Bearded Beardless Bearded - 3 1 6 2 3 1 - -Translating this into words, out of every 16 plants in the second -generation there were four long eared plants, three beardless and one -bearded; eight plants with ears of intermediate length, six beardless -and two bearded; and four short eared plants, three beardless and one -bearded. The illustration shows all these types. The experiment has -been repeated several times and the same proportions were invariably -obtained. The result, too, was independent of the way the cross was -made. Seed was collected separately from large numbers of single -plants of each type. The seed from each plant was sown by itself -in a row, so that its progeny could be separately observed. It was -found that all the plants of the second generation possessing ears of -intermediate length produced in the third generation plants with long -ears, short ears, and medium ears in the proportion of 1 : 1 : 2, the -same proportion in fact as in the second generation. Short eared plants -produced only short eared offspring, long eared plants only long eared -offspring. Bearded plants produced only bearded offspring. Beardless -plants, however, produced in some cases only beardless offspring, in -other cases both beardless and bearded offspring in the proportion of -three of the former to one of the latter. Out of every three beardless -plants only one was found to breed true, whilst two gave a mixed -progeny. It appears therefore that in the second generation some of the -types which occur breed true, whilst others do not. Some of the true -breeding individuals can be picked out at sight, for instance, those -with long or short bearded ears. Some of those which will not breed -true can also be recognised by inspection, for instance, all the plants -with ears of intermediate length. In other cases it is only possible to -pick out the individual plants which breed true by growing their seed -and observing how it behaves. If it produces progeny all of which are -like the plant from which the seed was obtained, that plant is a fixed -type and will breed true continuously in the future. The final result -of the experiment was to obtain in three years from the time the cross -was made, four fixed types which subsequent experience has shown breed -true continuously, a long eared bearded type, a short eared beardless -type, a long eared beardless type and a short eared bearded type. Of -these the second two are exactly like the two parental varieties, but -the first two are new, each combining one character from each parent. -These fixed types already existed in the second generation. Mendel’s -discoveries with peas showed how to pick them out. Obviously there is -no need for the years of roguing by which the older hybridisers used -to attempt to fix their desired type. All the types are present in the -second generation. Mendel has shown how the fixed ones may be picked -out. - -[Illustration: Fig. 4. _P_, _P_, the two parental types. _F₁_ the first -cross. _F₂_, 1-6, the types found in the second generation] - -The characters described above are not of any great economic -importance. Biffen has shown that such important characters as -baking strength and resistance to the disease known as yellow rust -behave on crossing in the same way as beard. Working on the lines of -the experiment described above he has succeeded in producing several -new varieties which in baking strength and in rust resistance are a -distinct advance on any varieties in cultivation in this country. -His method of working was to collect wheats from every part of the -world, to sow them and to pick out from the crop, which was usually -a mixed one, all the pure types he could. These were grown on small -plots for several years under close observation. Many were found to -be worthless and were soon discarded. Others were observed to possess -some one valuable character. Amongst these a pure strain of Red Fife -was obtained from Canadian seed, which was found to retain when grown -in England the excellent baking strength of the hard wheats of Canada -and North America. Again, other varieties were noticed to remain free -from yellow rust year after year, even when varieties on adjoining -plots were so badly infected that they failed to produce seed. Other -varieties, too, were preserved for the sturdiness of their straw, -their earliness in ripening, vigour of growth, or yielding capacity. -Many crosses were made with these as parents. The illustration shows -a corner of the Cambridge wheat-breeding enclosure including a -miscellaneous collection of parent varieties. The paper bags on the -ears show where crosses have been made. From the second generation -numbers of individual plants possessing desirable characters were -picked out, and the fixed types isolated in the third generation by -making cultures from the seed of these single plants. The seed from -these fixed types was sown on small field plots, at which stage many -had to be rejected because they were found wanting in some character -of great practical importance which did not make itself evident in -the breeding enclosure. The illustration shows a case in point. It -was photographed after heavy rain in July. The weakness of the straw -of the variety on the left had not been noticed in the enclosure. The -types which approved themselves on the small field plots were again -grown on larger plots so that their yield and milling and baking -characters could be tested. So far two types have survived the ordeal. -One combines the cropping power of the best English varieties with the -baking strength of North American hard wheat. It is the outcome of a -cross between Rough Chaff and Red Fife. Its average crop in 1911 was 38 -bushels per acre as the result of 28 independent trials, and, where the -local millers have found out its quality, it makes on the market four -or five shillings per quarter more than the ordinary English varieties. -The other resulted from a cross between Square Head’s Master and -a rust-resisting type isolated from a graded Russian wheat called -Ghirka. It is practically rust-proof. Consequently it yields a heavier -crop than any of the ordinary varieties which are all more or less -susceptible to rust. The presence of rust in and on the leaves hinders -the growth of the plant, lowers the yield, and increases the proportion -of shrivelled grains. It has been estimated that rust diminishes the -world’s wheat crop by something like one third. The new rust-proof -variety gave an average yield of about 6 bushels per acre more than -ordinary varieties on the average of 28 trials last year. It is called -Little Joss and is especially valuable in the Fens and other districts -where rust is more than usually virulent. - -[Illustration: Fig. 5. Corner of bird-proof enclosure showing a varied -assortment of parent varieties of wheat. Crosses have been made on some -of them as shown by the ears tied up in paper bags] - -[Illustration: - - Fig. 6. Field plots of two new varieties of the same parentage - which had approved themselves in the bird-proof enclosure. That - on the left had to be rejected on account of the weakness of - its straw. That on the right is the rust-proof variety known as - Little Joss. The photograph was taken after a storm which in - the open field found out the weak point of the one variety] - - - - -CHAPTER IV - -THE QUALITY OF WHEAT FROM THE MILLER’S POINT OF VIEW - - -To the miller the quality of wheat depends on three chief factors, the -percentage of dirt, weed seeds, and other impurities, the percentage of -water in the sample, and a complex and somewhat ill-defined character -commonly called strength. - -With the methods of growing, cleaning and thrashing wheat practised in -Great Britain, practically clean samples are produced, and home grown -wheat is therefore on the whole fairly free from impurities. This is, -however, far from the case with foreign wheats, many of which arrive at -the English ports in an extremely dirty condition. They are purchased -by millers subject to a deduction from the price for impurities above -the standard percentage which is allowed. The purchase is usually made -before the cargo is unloaded. Official samples are taken during the -unloading in which the percentage of impurities is determined, and the -deduction, if any, estimated. - -The percentage of water, the natural moisture as it is usually called, -varies greatly in the wheats of different countries. In home grown -wheats it is usually 16 per cent., but in very dry seasons it may be -much lower, and in wet seasons it may rise to 18 per cent. Foreign -wheats are usually considerably drier than home grown wheats. In -Russian wheats 12 per cent. is about the average, and that too is about -the figure for many of the wheats from Canada, the States, Argentina, -and parts of Australia. Indian wheats sometimes contain less than 10 -per cent. This is also about the percentage in the wheats of the arid -lands on the Pacific coast and in Australia. These figures show that -home grown wheats often contain as much as 5 per cent. more water -than the foreign wheats imported from the more arid countries. The -more water a wheat contains the less flour it will yield in the mill. -Consequently the less its value to the miller. A difference of 5 per -cent. of natural moisture means a difference in price of from 1_s._ -6_d._ to 2_s._ per quarter in favour of the drier foreign wheats. This -is one of the reasons why foreign wheats command a higher price than -those grown in this country. - -Turning to the third factor which determines the quality of wheat from -the miller’s point of view, we may for the present define strength -as the capacity for making bread which suits the public taste of the -present day. We shall discuss this point more fully when we deal with -the baking of bread. At present the only generally accepted method of -determining the strength of a sample of wheat is to mill it and bake -it, usually into cottage loaves. The strength of the wheat is then -determined from their size, shape, texture, and general appearance. A -really strong flour makes a large, well risen loaf of uniformly porous -texture. Wheats lacking in strength are known as weak. A weak wheat -makes a small flat loaf. In order to give a numerical expression to -the varying degrees of strength met with in different wheats, the Home -Grown Wheat Committee of the National Association of British and Irish -Millers have adopted a scale as the result of many thousand milling -and baking tests. On their scale the strength of the best wheat -imported from Canada, graded as No. 1 Manitoban, or from the States -graded as No. 1 Hard Spring, is taken as 100, that of the well-known -grade of flour known as London Households as 80, and that of the -ordinary varieties of home grown wheat, such as Square Head’s Master, -Browick, Stand Up, etc., as 65. The strength of most foreign wheats -falls within these limits. Thus the strength of Ghirka wheat from -Russia is about 85, of Choice White Karachi from India 75, of Plate -River wheat from the Argentine 80, etc. The strongest of all wheats is -grown in certain districts in Hungary. It is marked above 100 on the -scale, but it is not used for bread making. The soft wheats from the -more arid regions in Australia and the States are usually weaker than -average home grown samples, and are marked at 60. Rivet or cone wheat, -a heavy cropping bearded variety much grown by small holders,--since -the sparrow, which would ruin small plots of any other variety, seems -to dislike Rivet, possibly on account of its beard,--is the weakest of -all wheats, and is only marked at 20, which means that bread baked -from Rivet flour alone would be practically unsaleable. Rivet wheat -finds a ready sale, however, for making certain kinds of biscuits. - -[Illustration: Fig. 7. Loaves made from No. 1 Manitoba. Strength 100] - -[Illustration: Fig. 8. Loaves made from average English wheat. Strength -65] - -[Illustration: Fig. 9. Loaves made from Rivet wheat. Strength 20] - -In order to make flour which will bake bread to suit the taste of the -general public of the present day, the miller finds it necessary to -include in the mixture or blend of wheats which he grinds a certain -proportion of strong wheats such as Canadian, American, or Russian. -The quantity of strong wheat available is limited. Consequently strong -wheat commands a relatively high price. The average difference in price -of say No. 1 Manitoban and home grown wheat is about 5_s._ per quarter. -It is possible of course that the public taste in bread may change, -and damp close textured bread may become fashionable. In this case no -doubt the difference in price would disappear. Under present conditions -the necessity of including in his grinding mixture a considerable -proportion of strong foreign wheat is a distinct handicap against the -inland miller as compared with the port miller. The latter gets his -foreign wheat direct from the ship in which it is imported, whilst -the former has to pay railway carriage from the port to his mill. The -question naturally arises--is it not possible to grow strong wheats at -home and sell them to the inland miller? - -This question has been definitely answered by the work of the Home -Grown Wheat Committee during the last 12 years. The committee -collected strong wheats from every country where they are produced, -and grew them in England. From the first crop they picked out single -plants of every type represented in the mixed produce, for strong -wheats as imported are usually grades and not pure varieties. From the -single plants they have established pure strains of which they have -grown enough to mill and bake. From most of the strong wheats they -were unable to find any strain which would produce strong wheat in -England. Thus the strong wheat of Hungary when grown in England was -no stronger than any of the ordinary typical home grown wheats. But -from the strong wheat of Canada was isolated the variety known as Red -Fife, which makes up a very large proportion of the higher grades of -American and Canadian wheats, and this variety when grown in England -was found to continue to produce wheat as strong as the best Canadian. -Year after year it has been grown here, and when milled and baked its -strength has been found to be 100 or thereabouts on the scale above -described. Finally it was found that a strain of Red Fife which had -been brought over from Canada 20 years ago, and grown continuously in -the western counties ever since, under the name of Cook’s Wonder, was -still producing wheat which when ground and baked possessed a strength -of about 100. Thus it was conclusively proved that in the case of -Red Fife at any rate the English climate was capable of producing -really strong wheat. The strength of Hungarian and Russian wheats -appear to be dependent on the climate of those countries. Red Fife, -however, produces strong wheat wherever it is grown. It is interesting -to note that this variety although first exploited in Canada and the -States is really of European origin. It was taken out to Canada by an -enterprising Scotchman called Fife in a mixed sample of Dantzig wheat. -He grew it for some time and distributed the seed. Pure strains have -from time to time been selected by the American and Canadian experiment -stations. - -But the discovery that Red Fife would produce strong wheat in England -by no means solved the problem, for when the Home Grown Wheat Committee -distributed seed of their pure strain of that variety for extended -testing throughout the country, it was soon found to be only a poor -yielder except in a few districts. A yield of three quarters of strong -grain, even if it makes 40_s._ per quarter on the market, only gives to -the farmer a return of £6 per acre, as compared with a return of nearly -£8 from 4½ quarters of weak grain worth 35_s._ per quarter, which can -usually be obtained by growing Square Head’s Master, or some other -standard variety. - -[Illustration: - - Fig. 10. The left-hand loaf was made from average English - wheat. The loaf in the centre was made from Burgoyne’s Fife, - and is practically identical in size and shape with the - right-hand loaf which was made from imported No. 1 Manitoba] - -It was at this point that Mendel’s discoveries came to the rescue. -Working on the Mendelian lines already explained, Biffen at Cambridge -crossed Red Fife with many of the best English varieties. From one of -the crosses he was able to isolate a new variety in which are combined -the strength of Red Fife and the vigour and cropping power of the -English parent. This variety, known as Burgoyne’s Fife, has been grown -and distributed by members of the Millers’ Association. In 1911 on the -average of 28 separate trials it yielded 38 bushels per acre, which -is well above the average of the best English varieties. It has been -repeatedly milled and baked, and its strength is between 90 and 100, -practically the same as that of Red Fife. It has been awarded many -prizes at agricultural shows for quality, and it commands on markets -where the local millers have found out its baking qualities about the -same price as the best foreign strong wheats, that is to say from -4_s._ to 5_s._ per quarter more than the average price of home grown -wheat. Taking a fair average yield of wheat as four quarters per acre, -Burgoyne’s Fife gives to the farmer an increased return over the -ordinary varieties of about 16_s._ per acre. The introduction of such a -variety makes the production of strong wheat in England a practicable -reality, and will be a boon both to the farmer and to the inland -miller. It is likely too that the possibility of obtaining a better -return per acre will induce farmers to grow more wheat. Anything that -tends to increase the production of home grown wheat and makes Great -Britain less dependent on foreign supplies is a national asset of the -greatest value. - -It is of the greatest importance to the miller that he should be able -to determine the strength of the wheats he buys. Obviously the method -mentioned above, which entails milling enough of the sample to enable -him to bake a batch of bread, is far too lengthy to be of use in -assessing the value of a sample with a view to purchase. The common -practice is for the miller or corn merchant to buy on the reputation -of the various grades of wheat, which he confirms by inspection of -the sample. Strength is usually associated with certain external -characters which can readily be judged by the eye of the practised -wheat buyer. Strong wheats are usually red in colour, their skin is -thin and brittle, the grain is usually rather small, and has a very -characteristic horny almost translucent appearance. The grains are -extremely hard and brittle, and when broken the inside looks flinty. -On chewing a few grains the starch is removed and there remains in the -mouth a small pellet of gluten, which is tough and elastic like rubber, -but not sticky. - -Weak wheats as a rule possess none of these characters. Their colour -may be either red or white, their skin is commonly thick and tough, -the grain is usually large and plump, and often has an opaque mealy -appearance. It is soft and breaks easily, and the inside is white, soft -and mealy. Very little gluten can be separated from it by chewing, and -that little is much less tough and elastic than the gluten of a strong -wheat. - -These characters, however, are on the whole less reliable than the -reputation of the grade of wheat under consideration. To make a -reliable estimate of strength from inspection of a sample of wheat -requires a natural gift cultivated by continual practice. Even the -best commercial judges of wheat have been known to be deceived by -a sample of white wheat which subsequent milling and baking tests -showed to possess the highest strength. The mistake was no doubt due -to the great rarity of strength among white wheats. This rarity will -doubtless soon disappear now that a pure strain of White Fife has -been isolated and shown to possess strength quite equal to that of Red -Fife. Sometimes too the ordinary home grown varieties produce most -deceptive samples which show all the external characters of strong -wheats. Such samples, however, on milling and baking are invariably -found to possess the usual strength of home grown wheat, about 65 on -the scale. These considerations show the great need of a scientific -method of measuring strength, which can be carried out rapidly and on a -small sample of grain. This need is felt at the present time not only -by the miller and the merchant, but by the wheat breeder. For instance, -in picking out the plants possessing strong grain from cultures of the -second generation after making his crosses, the plant breeder up to the -present has had to rely on inspection by eye, and on the separation of -gluten by chewing, for a single plant obviously cannot yield enough -grain to mill and bake. This fact no doubt explains the differences of -opinion among plant breeders on the inheritance of strength, for it is -not every one who can acquire the power of judging wheat accurately by -his senses. Such a faculty is a personal gift, and is at best apt to -fail at times. - -The search for a rapid and accurate method of measuring strength has -for many years attracted the attention of investigators. As might be -expected most of the investigations have centred round the gluten, -for as mentioned above the gluten of a strong wheat is much more tough -and elastic than that of a weak wheat. Gluten is a characteristic -constituent of all wheats, and it is the presence of gluten which -gives to wheat flour the power of making bread. The other cereals, -barley, oats, maize and rice are very similar to wheat in their general -chemical composition, but they do not contain gluten. Consequently they -cannot make bread. - -In making bread flour is mixed with water and yeast. The yeast feeds -on the small quantity of sugar contained in the flour, fermenting -it and forming from it alcohol and carbon dioxide gas. The gluten -being coherent and tough is blown into numberless small bubbles by -the gas, which is thus retained inside the bread. On baking, the high -temperature of the oven fixes these bubbles by drying and hardening -their walls, and the bread is thus endowed with its characteristic -porous structure. If a cereal meal devoid of gluten is mixed with water -and yeast, fermentation will take place with formation of gas, but the -gas will escape at once, and the product will be solid and not porous. -Evidently from the baking point of view gluten is of the greatest -importance. One of the most obvious methods that have been suggested -for estimating the strength of wheat depends on the estimation of the -percentage of gluten contained in the flour. The method has not turned -out very successfully, for strength seems to depend rather on the -quality than on the quantity of gluten in the wheat. Much attention has -been given to the study of the causes of the varying quality of the -gluten of different wheats. Gluten for instance has been shown to be -a mixture of two substances, gliadin and glutenin, and the suggestion -has been made that its varying properties are dependent on the varying -proportions of these two substances present in different samples. This -suggestion however failed to solve the problem. - -After seven years of investigation the author has worked out the -following theory of the strength of wheat flours, which has finally -enabled him to devise a method which promises to be both accurate and -rapid, and to require so little flour that it can readily be used by -the wheat breeder to determine the strength of the grain in a single -ear. It has already been mentioned that a strong wheat is one that will -make a large loaf of good shape and texture. The strength of a wheat -may therefore be defined as the power of making a large loaf of good -shape and texture. Evidently strength is a complex of at least two -factors, size and shape, which are likely to be quite independent of -each other. Not infrequently, for instance, wheats are met with which -make large loaves of bad shape, or on the other hand, small loaves -of good shape. Probably therefore the size of the loaf depends on one -factor, the shape on another; and the failure of the many attempts -to devise a method of estimating strength have been caused by the -impossibility of measuring the product of two independent factors by -one measurement. - -It seemed a feasible idea that the size of the loaf might depend on -the volume of gas formed when yeast was mixed with different flours. -On mixing different flours with water and yeast it was found that for -the first two or three hours they all gave off gas at about the same -rate. The reason of this is that all flours contain about the same -amount of sugar, approximately one per cent., so that at the beginning -of the bread fermentation all flours provide the yeast with about the -same amount of sugar for food. But this small amount of sugar is soon -exhausted, and for its subsequent growth the yeast is dependent on the -transformation of some of the starch of the flour into sugar. Wheat -like many other seeds contains a ferment or enzyme called diastase, -which has the power of changing starch into sugar, and the activity of -this ferment varies greatly in different wheats. The more active the -ferment in a flour the more rapid the formation of sugar. Consequently -the more rapidly the yeast will grow, and the greater will be the -volume of gas produced in the later stages of fermentation in the -dough. As a rule it is not practicable to get the dough moulded into -loaves and put into the oven before it has been fermenting for about -six or eight hours. If the flour possesses an active ferment it will -still be rapidly forming gas at the end of this time, and the loaf will -go into the oven distended with gas under pressure from the elasticity -of the gluten which forms the walls of the bubbles. The heat of the -oven will cause each gas bubble to expand, and a large loaf will be the -result. If the ferment of the flour is of low activity it will not be -able to keep the yeast supplied with all the sugar it needs, the volume -of gas formed in the later stages of the fermentation of the dough will -be small, the dough will go into the oven without any pressure of gas -inside it, little expansion will take place as the temperature rises, -and a small loaf will be produced. - -From these facts it is quite easy to devise a method of estimating how -large a loaf any given flour will produce. The following method is that -used by the author. A small quantity of the flour, usually 20 grams, -is weighed out and put into a wide mouthed bottle. A flask of water -is warmed to 40° C., of this 100 c.c. is measured out, and into it 2½ -grams of compressed yeast is intimately mixed, 20 c.c. of the mixture -being added to the 20 grams of flour in the bottle. The flour and -yeast-water are then mixed into a cream by stirring with a glass rod. -The bottle is then placed in a vessel of water which is kept by a small -flame at 35° C. The bottle is connected to an apparatus for measuring -gas, and the volume of gas given off every hour is recorded. As already -mentioned all flours give off about the same volume of gas during the -first three hours. After this length of time the volume of gas given -off per hour varies greatly with different flours. Thus a flour which -will bake a large loaf gives off under the conditions above described -about 20 c.c. of gas during the sixth hour of fermentation, whilst a -flour which bakes a small tight loaf gives off during the sixth hour of -fermentation only about 5 c.c. of gas. - -Having devised a feasible method of estimating how large a loaf any -given flour will make, the problem of the shape and texture still -remains. Previous investigators had exhausted almost every possible -chemical property of gluten in their search for a method of estimating -strength. The author therefore determined to study its physical -properties. Now gluten is what is known as a colloid substance, like -albumen the chief constituent of white of egg, casein the substance -which separates when milk is curdled, or clay which is a well known -constituent of heavy soils. Such colloid substances can scarcely be -said to possess definite physical properties of their own, for their -properties vary so largely with their surroundings. The white of a -fresh egg is a thick glairy liquid. On heating it becomes a white -opaque solid, and the addition of certain acids produces a similar -change in its properties. Casein exists in fresh milk in solution. The -addition of a few drops of acid causes it to separate as finely divided -curd. If, however, the milk is warmed before the acid is added the -casein separates as a sticky coherent mass. Every farmer knows that -lime improves the texture of soils containing much clay, because the -lime causes the clay to lose its sticky cohesive nature. - -Such instances show that the properties of colloid substances are -profoundly modified by the presence of chemical substances. Wheat, -like almost all plant substances, is slightly acid, and the degree of -acidity varies in different samples. Accordingly the effect of acids on -the physical properties of gluten was investigated, and it was found -that by placing bits of gluten in pure water and in acid of varying -concentration it could be made to assume any consistency from a state -of division so fine that the separate particles could not be seen, -except by noticing that their presence made the water milky, to a tough -coherent mass almost like indiarubber (Fig. 11). It was found, however, -that the concentration of acid in the wheat grain was never great -enough to make the gluten really coherent. - -[Illustration: Fig. 11. - -Gluten in pure water; soft, but tough and elastic - -Gluten in very weak hydrochloric acid (3 parts in 100,000 of water); it -floats about in powder, having entirely lost cohesion, and makes the -water milky - -Gluten in hydrochloric acid (3 parts in 1000 of water); very hard and -tough] - -But wheat contains also varying proportions of such salts as chlorides, -sulphates and phosphates, which are soluble in water, and the action -of such salts on gluten was next tried. It was at once found that -these salts in the same concentration as they exist in the wheat grain -were capable of making gluten coherent, but that the kind of coherence -produced was peculiar to each salt. Phosphates produce a tough and -elastic gluten such as is found in the strongest wheats. Chlorides and -sulphates on the other hand make gluten hard and brittle, like the -gluten of a very weak wheat (Fig. 12). - -The next step was to make chemical analyses to find out the amount of -soluble salts in different wheats. Strong wheats of the Fife class -were found to contain not less than 1 part of soluble phosphate in -1000 parts of wheat, whilst Rivet wheat, the weakest wheat that comes -on the market, contained only half that amount. Rivet, however, was -found to be comparatively rich in soluble chlorides and sulphates, -which are present in very small amounts in strong wheats of the Fife -class. Ordinary English wheats resemble Rivet, but they contain rather -more phosphate and rather less chlorides and sulphates. After making a -great many analyses it was found that the amount of soluble phosphate -in a wheat was a very good index of the shape and texture of the loaf -which it would make. The toughness and elasticity of the gluten no -doubt depend on the concentration of the soluble phosphate in the wheat -grain, the more the soluble phosphate the tougher and more elastic -the gluten, and a tough and elastic gluten holds the loaf in shape as -it expands in the oven, and prevents the small bubbles of gas running -together into large holes and spoiling the texture. - -[Illustration: Fig. 12. - -Gluten in water containing both acid and phosphate; very tough and -elastic - -Gluten in water containing both acid and sulphates. It shows varying -degrees of coherence, but is brittle or “short”] - -These facts suggest at once a method for estimating the shape and -texture of the loaf which can be made from any given sample of wheat. -An analysis showing the amount of soluble phosphate in the sample -should give the desired information. But unfortunately such an analysis -is not an easy one to make, and requires a considerable quantity of -flour. In making these analyses it was noticed that when the flours -were shaken with water to dissolve the phosphate, and the insoluble -substance removed by filtering, the solutions obtained were always more -or less turbid, and the degree of turbidity was found to be related -to the amount of phosphate present and to the shape of loaf produced. -On further investigation it was found that the turbidity was due to -the fact that the concentration of acid and salts which make gluten -coherent, also dissolve some of it, and gluten like other colloids -gives a turbid solution. It was also found that the amount of gluten -dissolved, and consequently the degree of turbidity, is related to -the shape of the loaf which the flour will produce. Now it is quite -easy to measure the degree of turbidity of a solution by pouring the -solution into a glass vessel below which a small electric lamp is -placed, and noting the depth of the liquid through which the filament -of the lamp can just be seen. The turbidities were, however, so slight -that it was found necessary to increase them by adding a little iodine -solution which gives a brown milkiness with solutions of gluten, the -degree of milkiness depending on the amount of gluten in the solution. -In this way a method was devised which is rapid, easy, and can be -carried out with so little wheat that the produce of one ear is amply -sufficient. It can therefore be used by the plant breeder for picking -out from the progeny of his crosses those individual plants which are -likely to give shapely loaves. The method is as follows: An ear of -wheat is rubbed out and ground to powder in a small mill. One gram of -this powder, or of flour if that is to be tested, is weighed out and -put into a small bottle. To it is added 20 c.c. of water. The bottle -is then shaken for one hour. At the end of this time the contents are -poured onto a filter. To 15 c.c. of the solution 1½ c.c. of a weak -solution of iodine is added, and after standing for half an hour the -turbidity test is applied. Working in this way it is possible to see -through only 10 c.m. of the solution thus obtained from such a wheat as -Red Fife, as compared with 25 c.m. in the case of Rivet. Other wheats -yield solutions of intermediate opacity. This method is now being -tested in connection with the Cambridge wheat breeding experiments. - - - - -CHAPTER V - -THE MILLING OF WHEAT - - -In order that wheat may be made into bread it is necessary that it -should be reduced to powder. In prehistoric times this was effected by -grinding the grain between stones. Two stones were commonly used, the -lower one being more or less hollowed on its upper surface so as to -hold the grain while it was rubbed by the upper one. As man became more -expert in providing for his wants, the lower stone was artificially -hollowed, and the upper one shaped to fit it, until in process of time -the two stones assumed the form of a primitive mortar and pestle. - -The next step in the evolution of the mill was to make a hole or groove -in the side of the lower stone through which the powdered wheat could -pass as it was ground. This device avoided the trouble of emptying the -primitive mill, and materially saved the labour of the grinder. Such -mills are still in use in the less civilised countries in the East, and -are of course worked by hand as in primitive times. - -They gradually developed as civilization progressed into the stone -mills which ground all the breadstuffs of the civilised world until -about 40 years ago. The old fashioned stone mill was, and indeed still -is, a weapon of the greatest precision. It consists of a pair of stones -about four feet in diameter, the lower of which is fixed whilst the -upper is made to revolve by mechanical power at a high speed. Each -stone is made of a large number of pieces of a special kind of hard -stone obtained from France. These pieces are cemented together, and -the surfaces which come into contact are patiently chipped until they -fit one another to a nicety all over. The surface of the lower stone -is then grooved so as to lead the flour to escape from between the -stones at definite places where it is received for further treatment. -The grain to be ground is fed between the stones through a hole at the -centre of the upper stone. It has been stated above that the surfaces -of the two stones are in contact. As a matter of fact this is not -strictly true. The upper stone is suspended so that the surfaces are -separated by a small fraction of an inch, and it will be realised -at once that this suspension is a matter of the greatest delicacy. -To balance a stone weighing over half a ton so that, when revolving -at a high rate of speed, it may be separated from its partner at no -point over its entire surface of about 12 square feet by more than -the thickness of the skin of a grain of wheat, and yet may nowhere -come into actual contact, is an achievement of no mean order. Stone -mills of this kind were usually driven by water power, or in flat -neighbourhoods by wind power, though in some cases steam was used. - -It was the common practice to subject the ground wheat from the stones -to a process of sifting so as to remove the particles of husk from -the flour. The sifting was effected by shaking the ground wheat in a -series of sieves of finely woven silk, known as bolting cloth. In this -way it was possible to obtain a flour which would make a white bread. -The particles of husk removed by the sifting were sold to farmers for -food for their animals, under the name of bran, sharps, pollards, or -middlings, local names for products of varying degrees of fineness, -which may be classed together under the general term wheat offals. The -ideal of the miller was to set his stones so that they would grind -the flour to a fine powder without breaking up the husk more than was -absolutely necessary. When working satisfactorily a pair of stones were -supposed to strip off the husk from the kernel. The kernel should then -be finely pulverised. The husk should be flattened out between the -stones, which should rub off from the inside as completely as possible -all adhering particles of kernel. If this ideal were attained, the -mill would yield a large proportion of fairly white flour, and a small -proportion of husk or offals. - -As long as home grown wheats were used this ideal could be more or -less attained because the husk of these wheats is tough and the kernel -soft. Comparatively little grinding suffices to reduce the kernel to -the requisite degree of fineness, and this the tough husk will stand -without being itself unduly pulverised. Consequently the husk remains -in fairly large pieces, and can be separated by sifting, with the -result that a white flour can be produced. But home grown wheat ceased -to provide for the wants of the nation more than half a century ago. -Already in 1870 half the wheat ground into flour in the United Kingdom -was imported from abroad, and this proportion has steadily increased, -until at the present time only about one-fifth of the wheat required is -grown at home. Many of the wheats which are imported are harder in the -kernel, and thinner and more brittle in the husk, than the home grown -varieties. Consequently they require more grinding to reduce the kernel -to the requisite degree of fineness, and their thin brittle husk is -not able to resist such treatment. It is itself ground to powder along -with the kernel, and cannot be completely separated from the flour -by sifting. Such wheats therefore, when ground between stones, yield -flour which contains much finely divided husk, and this lowers its -digestibility and gives it a dark colour. - -In the decades before 1870 when the imports of foreign wheats first -reached serious proportions, and all milling was done by stones, dark -coloured flours were common, and people would no doubt have accepted -them without protest, if no other flours had been available. But as it -happened millers in Hungary, where hard kernelled, thin skinned wheats -had long been commonly grown, devised the roller milling process, which -produces fine white flour from such wheats, no matter how hard their -kernels or how thin their skins. The idea of grinding wheat between -rollers was at once taken up in America and found to give excellent -results with the hard thin skinned wheats of the north-west. The fine -white flours thus produced were sent to England, and at once ousted -from the home markets the dark coloured flours produced from imported -wheats in the English stone mills. The demand for the white well-risen -bread produced from these roller milled imported flours showed at once -that the public preferred such bread to the darker coloured heavier -bread yielded by stone-ground flours, especially those made from the -thin skinned foreign wheats. - -This state of things was serious both for the millers and the farmers. -The importation of flour instead of wheat must obviously ruin the -milling industry, and since wheat offals form no inconsiderable item -in the list of feeding stuffs available for stock keepers, a decline -of the milling industry restricts the supply of food for his stock, -and thus indirectly affects the farmer. At the same time the preference -shown by the public for bread made from fine white imported flour, to -some extent depreciated the value of home grown wheat. - -It was by economic conditions of this kind that the millers were -compelled in the early seventies to alter their methods. The large -firms subscribed more capital and installed roller plant in their -mills. These at once proved a success and the other firms have followed -suit. At the present time considerably more than 90 per cent. of the -flour used in this country is the product of roller mills. The keen -competition which has arisen in the milling industry during the last 35 -years has produced great improvements in roller plant, and the methods -of separation now in use yield flours which in the opinion of the -miller, and apparently too in the opinion of the general public, are -far in advance of the flours which were produced in the days of stone -milling. - -Perhaps the first impression which a visitor to a modern roller mill -would receive is the great extent to which mechanical contrivances have -replaced hand labour. Once the wheat has been delivered at the mill -it is not moved again by hand until it goes away as flour and offals. -It is carried along by rapidly moving belts, elevated by endless -chains carrying buckets, allowed to fall again by gravity, or perhaps -in other cases transported by air currents. Another very striking -development is the great care expended in cleaning the grain before -it is ground. This cleaning is the first process to which the wheat -is subjected. It is especially necessary in the case of some of the -foreign wheats which arrive in this country in a very dirty condition. -The impurities consist of earth, weed seeds, bits of husk and straw; -iron nails, and other equally unlikely objects are by no means -uncommon. Some of these are removed by screens, but besides screening -the wheat is actually subjected to the process of washing with water. -For this purpose it is elevated to an upper floor of the mill, and -allowed to fall downwards through a tall vessel through which a stream -of water is made to flow. As it passes through the water it is scrubbed -by a series of mechanically driven brushes to remove the earthy matter -which adheres to the grain. This is carried away by the stream of water. - -After cleaning the grain next undergoes the process of conditioning. -The object of this process is so to adjust the moisture of the grain -that the husk may attain its maximum toughness compatible with a -reasonable degree of brittleness of kernel, the idea being to powder -the kernel with the minimum of grinding and without unduly powdering -the husk. By attention to this process separation of flour and husk -is made easier and more complete. The essential points in the process -are to moisten the grain, either in the course of cleaning as above -described, or if washing is not necessary, by direct addition of water. -The moisture is given some time to be absorbed into the grain, which is -then dried until the moisture content falls to what experience shows to -be the most successful figure for the wheat in question. - -[Illustration: Fig. 13. First break rolls seen from one end. The ribs -can just be seen where the two rolls touch] - -Cleaning and conditioning having been attended to, the grain is now -conveyed to the mill proper. This of course is done by a mechanical -arrangement which feeds the grain at any desired rate into the hopper -which supplies the first pair of rolls. These rolls consist of a pair -of steel cylinders usually 10 inches in diameter and varying in length -from 20 inches to 5 feet according to the capacity of the mill. The -surfaces of the cylinders are fluted or ribbed, the distance from -rib to rib being about one-tenth of an inch. The rollers are mounted -so that the distance between their surfaces can be adjusted. They -are set so that they will break grains passing between them to from -one-half to one-quarter their original size. They are made to revolve -so that the parts of the surfaces between which the grains are nipped -are travelling in the same direction. One roll revolves usually at -about 350 revolutions per minute, the other at rather less than half -that rate (Fig. 14). It is obvious from the above description that a -grain of wheat falling from the hopper on to the surface of the moving -rollers will be crushed or nipped between them, and that since the -rollers are moving at different rates, it will at the same time be more -or less torn apart. By altering the distance between the rollers and -their respective speeds of revolution the relative amounts of nipping -and tearing can be adjusted to suit varying conditions. - -[Illustration: - - Fig. 14. Break rolls. The large and small cog-wheels are the - simplest device used to give the two rolls different speeds. - The larger cog-wheel is driven by power and drives the smaller, - of course at a much higher rate of revolution] - -The passage of the grain through such a pair of rollers is known -technically as a break. Its object is to break or tear open the grain -with the least possible amount of friction between the grain and the -grinding surfaces. Since the rollers are cylindrical it is obvious that -the grain will only be nipped at one point of their surfaces, and even -here the friction is reduced as much as possible by making both the -grinding surfaces move in the same direction. As already explained it -can be diminished, if the condition of the wheat allows, by diminishing -the difference in speed between the two rolls. The result of the first -break is to tear open the grains. At the same time a small amount of -the kernel will be finely powdered. The rest of the kernel and husk -will still remain in comparatively large pieces. The tearing open of -the grain sets free the dirt which was lodged in the crack or furrow -which extends from end to end of the grain. This dirt cannot be removed -by any method of cleaning. It only escapes when the grain is torn -open in the break. It is generally finely divided dirt and cannot be -separated from the flour formed in this process. Consequently the -first break flour is often more or less dirty, and the miller tries to -adjust his first break rolls so that they will form as little flour as -possible. The first break rolls not only powder a little of the kernel, -but they also reduce to a more or less fine state of division a little -of the husk. - -The result of the passage of the grain through the first break rolls -is to produce from it a mixture of a large quantity of comparatively -coarse particles of kernel to many of which husk is still adherent, -a small quantity of finely divided flour which is more or less -discoloured with dirt, and a small quantity of finely divided husk. -This mixture, which is technically known as stock, is at once subjected -to what is called separation, with the object of separating the flour -from the other constituents before it undergoes any further grinding. -It is one of the guiding principles of modern milling that the flour -produced at each operation should be separated at once so as to reduce -to a minimum the grinding which it has to undergo. Separation is -brought about by the combination of two methods. The stock is shaken -in contact with a screen made of bolting silk so finely woven that it -contains from 50 to 150 meshes to the inch, according to the fineness -of the flour which it is desired to separate. The shaking is effected -in several different ways. Sometimes the silk is stretched on a frame -so as to make a kind of flat sieve. This is shaken mechanically whilst -the stock is allowed to trickle over its surface, so that the finely -divided particles of flour may fall through the meshes and be collected -separately from the larger particles which remain on the top. These -larger particles are partly heavy bits of broken kernel and partly -light bits of torn husk. In order to separate them advantage is taken -of the fact that a current of wind can be so adjusted that it will blow -away the light and fluffy husk particles without disturbing the heavy -bits of kernel. By means of a mechanically driven fan a current of -air is blown over the surface of the sieve, in the direction opposite -to that in which the stock is travelling. As the stock rolls over and -over in its passage from the upper to the lower end of the inclined -sieve the fluffy particles of husk are picked up by the air current -and carried back to the top of the sieve where they fall, as the -current slackens, into a receptacle placed to receive them. Thus by -the combination of sifting and air carriage the stock is separated -into a small quantity of finished flour, a small quantity of finished -husk or offal, and a large quantity of large particles of kernel with -husk still adhering to some of them. These large particles, which -are called semolina, of course require further grinding. Different -methods of sifting are often used in place of the one above described, -especially for completing the purification of the flour. Sometimes the -silk is stretched round a more or less circular frame so as to form -a long cylinder covered with silk. The stock is delivered into the -higher end of this cylinder which is made to revolve. This causes the -stock to work its way through the cylinder, and during its progress the -finely ground flour finds its way through the meshes, and is separated -as before from the coarser particles. Such a revolving sieve is known -as a reel. In a somewhat similar arrangement known as a centrifugal -a series of beaters is made to revolve rapidly inside a stationary -cylindrical sieve. The stock is admitted at one end and is thrown by -the revolving beaters against the silk cover. The finer particles are -driven through the meshes of the silk, the coarser particles find their -way out of the cylinder at the other end. Sometimes for separating -very coarse particles wire sieves of 30 meshes, or thereabouts, to the -inch are used. Whatever the method the object is to separate at once -the finished flour and offal from the large particles of kernel which -require further grinding. - -[Illustration: - - Fig. 15. A pair of reduction rolls. They are smooth, and the - cog-wheels being nearly of the same size the speed of the two - rolls is nearly equal] - -These large particles, semolina, are next passed between one or more -pairs of smooth rolls known as reduction rolls (Fig. 15). These are -set rather nearer together than the break rolls, and the difference -in speed between each roll and its partner is quite small. The object -of reduction is to reduce the size of the large particles of semolina -and to produce thereby finely divided flour. The stock from the first -pair or pairs of reduction rolls contains much finely ground flour -mixed with coarser particles of kernel with or without adherent husk. -It is at once submitted to the separation and purification processes -as above described. This yields a large quantity of finished flour -which is very white and free from husk. It represents commercially -the highest grade of flour separated in the mill and is described -technically as patents. A small amount of finished offal is also -separated at this stage. - -The coarse particles of kernel with adherent husk from which the flour -and offal have been separated are now passed through a second pair of -break rolls more finely fluted than before, known as the second break. -These are set closer together than the first break rolls. Their object -is to rub off more kernel from the husk. The stock from them is again -separated, the flour and finished offal being removed as before. The -coarser particles are again reduced by smooth reduction rolls, and a -second large quantity of flour separated. This is commercially high -grade flour and is usually mixed with the patents already separated. -The coarse particles left after this separation are usually subjected -to a third and a fourth break, each of which is succeeded by one or -two reductions. Separation of the stock and purification of the flour -take place after each rolling, so that as soon as any flour or husk is -finely ground it may be at once separated without further grinding. -The last pair of fluted rolls, the fourth break, are set so closely -together that they practically touch both sides of the pieces of -husk which pass through them. They are intended to scrape the last -particles of kernel from the husk. This is very severe treatment, and -usually results in the production of much finely powdered husk which -goes through the sifting silk and cannot be separated from the flour. -The flour from the fourth break is therefore usually discoloured by the -presence of much finely divided husk. For this reason it ranks as of -low commercial grade. The later reductions too yield flours containing -more or less husk, which darkens their colour. They are usually mixed -together and sold as seconds. - -The fate of the germ in the process of roller milling is a point of -considerable interest, both on account of the ingenious way in which -it is removed, and because of the mysterious nutritive properties -which it is commonly assumed to possess. The germ of a grain of wheat -forms only about 1½ per cent. by weight of the grain. It differs in -composition from the rest of the grain, being far richer in protein, -fat, and phosphorus. Its special feeding value can, however, scarcely -be explained in terms of these ingredients, for its total amount is so -small that its presence or absence in the flour can make only a very -slight difference in the percentages of these substances. But this -point will be discussed fully in a subsequent chapter. Here it is the -presence of the fat which is chiefly of interest. According to the -millers the fat of the germ is prone to become rancid, and to impart -to the flour, on keeping, a peculiar taste and odour which affects its -commercial value. They have therefore devised with great ingenuity a -simple method of removing it. This method depends on the fact that the -presence in the germ of so much fat prevents it from being ground to -powder in its passage between the rolls. Instead of being ground it -is pressed out into little flat discs which are far too large to pass -with the flour through the sifting silks or wires, and far too heavy to -be blown away by the air currents which remove the offals. The amount -which is thus separated is usually about 1 per cent. of the grain so -that one third of the total quantity of germ present in the grain is -not removed as such. Considerable difficulties arise in attempting to -trace this fraction, and at present it is impossible to state with -certainty what becomes of it. The germ which is separated is sold by -the ordinary miller to certain firms which manufacture what are known -as germ flours. It is subjected to a process of cooking which is said -to prevent it from going rancid, after which it is ground with wheat, -the product being patent germ flour. - - - - -CHAPTER VI - -BAKING - - -In discussing the method of transforming flour into bread it will be -convenient to begin by describing in detail one general method. The -modifications used for obtaining bread of different kinds, and for -dealing with flours of different qualities will be shortly discussed -later when they can be more readily understood. - -Bread may be defined as the product of cooking or baking a mixture of -flour, water, and salt, which is made porous by the addition of yeast. -It is understood to contain no other substances than these--flour, -salt, water and yeast. - -In the ordinary process the first step is to weigh out the flour which -it is proposed to bake. This is then transferred to a vessel which in a -commercial bakery is usually a large wooden trough, in a private house -an earthenware bowl. The necessary amount of yeast is next weighed out -and mixed with water. Nowadays compressed or German yeast is almost -always used at the rate of 1 to 2 lbs. per sack or 280 lbs. of flour. -For smaller quantities of flour relatively more yeast is needed, for -instance 2 ozs. per stone. Formerly brewers’ yeast or barm was used, -but its use has practically ceased because it is difficult to obtain -of standard strength. Some people who profess to be connoisseurs of -bread still prefer it because as they say it gives a better flavour -to the bread. The water with which the yeast is mixed is warmed so as -to make the yeast more active. The flour is then heaped up at one end -of the vessel in which the mixing is to take place, and salt at the -rate of 2 to 5 lbs. per sack is thoroughly stirred into it. A hollow -is then made in the heap of flour into which the mixture of yeast and -water is poured. More warm water is added so that enough water in all -may be present to convert all, or nearly all, the flour into dough of -the required consistency. When dealing with a flour with which he is -familiar the baker knows by experience how much water he requires per -sack. In the case of an unaccustomed brand of flour he determines the -amount by a preliminary trial with a small quantity (Figs. 16 and 17). -Flour from the heap is then stirred into the water until the whole of -the flour is converted into a stiff paste or dough as it is called. -By this method a little dry flour will always separate the dough from -the sides of the vessel and this will prevent the dough from sticking -to the vessel and the hands. The dough is then thoroughly worked or -kneaded so as to ensure the intimate mixture of the ingredients. The -vessel is then covered to keep the dough warm. In private houses -this is ensured by placing the vessel near the fire. In bakeries the -room in which the mixing is conducted is usually kept at a suitable -temperature. The yeast cells which are thoroughly incorporated in the -dough, find themselves in possession of all they require to enable them -to grow. The presence of water keeps them moist, and dissolves from -the flour for their use sugar and salts: the dough is kept warm as -above explained. Under these conditions active fermentation takes place -with the formation of alcohol and carbon dioxide gas. The alcohol is -of no particular consequence in bread making, the small amount formed -is probably expelled from the bread during its stay in the oven. The -carbon dioxide, however, plays a most important part. Being a gas it -occupies a large volume, and its formation throughout the mass of the -dough causes the dough to increase greatly in volume. The dough is said -by the housewife to rise, by the professional baker to prove. - -[Illustration: - - Fig. 16. Apparatus arranged for a baking test. Four loaves - which have just been scaled and moulded are seen in an - incubator where they are left to rise or prove before being - transferred to the oven] - -[Illustration: - - Fig. 17. The loaves shown in the last figure have just been - baked and are ready to be taken out of the oven, the door of - which is open. Note the different shapes. That on the right - hand is obviously shown by the test to be made from a strong - flour, the other from a very weak flour] - - -The process of kneading causes the particles of gluten to absorb -water and to adhere to one another, so that the dough may be regarded -as being composed of innumerable bubbles each surrounded by a thin -film of gluten, in or between which lie the starch grains and other -constituents of the flour. Each yeast cell as above explained forms a -centre for the formation of carbon dioxide gas, which cannot escape -at once into the air, and must therefore form a little bubble of -gas inside the particular film of gluten which happens to surround -it. The expansion of the dough is due to the formation inside it of -thousands of these small bubbles. It is to the formation of these -bubbles too that the porous honey-combed structure of wheaten bread is -due. Also since the formation of the bubbles is due to the retention -of the carbon dioxide by the gluten films, such a porous structure is -impossible in bread made from the flour of grains which do not contain -gluten. - -The rising of the dough is usually allowed to proceed for several -hours. The baker finds by experience how long a fermentation is -required to give the best results with the flours he commonly uses. -When the proper time has elapsed, the dough is removed from the trough -or pan in which it was mixed to a board or table, previously dusted -with dry flour to prevent the dough adhering to the board or to the -hands. It is then divided into portions of the proper weight to -make loaves of the desired size. This process is known technically -as scaling. Usually 2 lbs. 3 ozs. of dough is allowed for baking a 2 -lb. loaf. Each piece of dough is now moulded into the proper shape if -it is desired to bake what is known as a cottage loaf, or placed in -a baking tin if the baker is satisfied with a tinned loaf. In either -case the dough is once more kept for some time at a sufficiently warm -temperature for the yeast to grow so that the dough may once more be -filled with bubbles of carbon dioxide gas. As soon as this second -rising or proving has proceeded far enough the loaves are transferred -to the oven. Here the intense heat causes the bubbles of gas inside -the dough to expand so that a sudden increase in the size of the loaf -takes place. At the same time the outside of the loaf is hardened and -converted into crust. - -After remaining in the oven for the requisite time the bread is -withdrawn and allowed to cool as quickly as possible, after which it is -ready for use or sale. - -The method of baking which has been described above is known as the -off-hand or straight dough method. It possesses the merit of rapidity -and simplicity, but it is said by experts that it does not yield the -best quality of bread from certain flours. Perhaps the commonest -variation is that known as the sponge and dough method, which is -carried out as follows. As before, the requisite amount of flour is -weighed out into the mixing trough, and a depression made in it for -the reception of the water and yeast. These are mixed together in the -proper proportions, enough being taken to make a thick cream with -about one quarter of the flour. This mixture is now poured into the -depression in the flour, and enough of the surrounding flour stirred -into it to make a thick cream or sponge as it is called. At the same -time a small quantity of salt is added to the mixture. The sponge is -allowed to ferment for some hours, being kept warm as in the former -method. As soon as the time allowed for the fermentation of the sponge -has elapsed, more water is added, so that the whole or nearly the whole -of the flour can be worked up into dough. This dough is immediately -scaled and moulded into loaves, which after being allowed to prove -or rise for some time are baked as before. This method is used for -flours which do not yield good bread when they are submitted to long -fermentation. In such cases the mellow flours, which will only stand a -very short fermentation, are first weighed out into the mixing trough, -and a depression made in the mass of flour into which a quantity of -strong flour which can be fermented safely for a long time is added. It -is this last addition which is mixed up into the sponge to undergo the -long preliminary fermentation. The rest of the flour is mixed in after -this first fermentation is over, so that it is only subjected to the -comparatively slight fermentation which goes on in the final process of -proving. - -Many other modifications are commonly practised locally, their object -being for the most part to yield bread which suits the local taste. -It will suffice to mention one which has a special interest. In this -method the essentially interesting point is the preparation of what is -known as a ferment. For this purpose a quantity of potatoes is taken, -about a stone to the sack of flour. After peeling and cleaning they -are boiled and mashed up with water into a cream. To this a small -quantity of yeast is added and the mixture kept warm until fermentation -ceases, as shown by the cessation of the production of gas. During -this fermentation the yeast increases enormously, so that a very small -quantity of yeast suffices to make enough ferment for a sack of flour. -The flour is now measured out into the trough, and the ferment and some -additional water and salt added so that the whole can be worked up into -dough. Scaling, moulding, and baking are then conducted as before. This -method was in general use years ago when yeast was dear. It has fallen -somewhat into disuse in these days of cheap compressed yeast, in fact -the use of potatoes nowadays would make the process expensive. - -In private houses and in the smaller local bakeries the whole of the -processes described above are carried out by hand. During the last -few decades many very large companies have been formed to take up -the production of bread on the large scale. This has caused almost -a revolution of the methods of manipulating flour and dough, and in -many cases nowadays almost every process in the bakery is carried out -by machinery. In many of the larger bakeries doughing and kneading -are carried out by machines, and this applies also to the processes -of scaling and moulding. A similar change has taken place too in the -construction of ovens. Years ago an oven consisted of a cavity in a -large block of masonry. Wood was burned in the cavity until the walls -attained a sufficiently high temperature. The remains of the fuel were -then raked out and the bread put in and baked by radiation from the hot -walls. - -Nowadays it is not customary to burn fuel in the oven itself, nor is -the fuel always wood or even coal. The fuel is burned in a furnace -underneath the oven, and coal or gas is generally used. Sometimes -however the source of heat is electricity. In all cases it is still -recognised that the heat should be radiated from massive solid walls -maintained at a high temperature. In the latest type of oven the heat -is conducted through the walls by closed iron tubes containing water, -which of course at the high temperatures employed becomes superheated -steam. It is recognised that the ovens commonly provided in modern -private houses, whether heated by the fire of the kitchen range, or by -gas, are not capable of baking bread of the best quality, because their -walls do not radiate heat to the same degree as the massive walls of a -proper bake oven. - -It is commonly agreed that bread, in the usual acceptation of the term, -should contain nothing but flour, yeast, salt, and water; or if other -things are present they should consist only of the products formed by -the interaction of these four substances in the process of baking. -Millers and bakers have, however, found by experience that the addition -of certain substances to the flour or to the dough may sometimes enable -them substantially to improve the market value of the bread produced by -certain flours. The possible good or bad effect of such additions on -the public health will be discussed in a later chapter. It may be of -interest here to mention some of the substances which are commonly used -as flour or bread improvers by millers and bakers, and to discuss the -methods by which they effect their so called improvements. - -In a former chapter we have discussed the quality of wheat from the -miller’s point of view, and during the discussion certain views were -enunciated on the subject of strength. It was pointed out that a strong -flour was one which would make a large well-shaped loaf, and that the -size of the loaf was dependent on the flour being able to provide sugar -for the yeast to feed upon right up to the moment when the loaf goes -into the oven. This can only occur when the flour contains an active -ferment which keeps changing the starch into sugar. That this view is -generally accepted in practice is shown by the fact that, when using -flours deficient in such ferment, bakers commonly add to the flour, -yeast, salt, and water, a quantity of malt extract, the characteristic -constituent of which is the sugar producing ferment of the malt. This -use of malt extract is now extending to the millers, several of whom -have installed in their mills plant for spraying into their flour a -strong solution of malt extract. It seems to be agreed by millers and -bakers generally that such an addition to a flour which makes small -loaves distinctly increases the size of the loaf. There can be no doubt -that this effect is produced by the ferment of the malt extract keeping -up the supply of sugar, and thus enabling the yeast to maintain the -pressure of gas in the dough right up to the moment when it goes into -the oven. - -The view that the shape of the loaf is due to the effect of salts, and -particularly of phosphates, on the coherence of the gluten has also -been put to practical use by the millers and the bakers. Preparations -of phosphates under various fancy names are now on the market, and are -bought by bakers for adding to the flour to strengthen the gluten and -produce more shapely loaves. A few millers too are beginning to spray -solutions of phosphates into their flours with the same object in view, -and such additions are said to make material improvements in the shape -of the loaf produced by certain weak flours. - -These two substances, malt extract and phosphates, are added to the -flour with the definite object of improving the strength and thus -making larger and more shapely loaves. But there is a second class of -substances which are commonly added to flours, not in the mill but in -the process of bread making, with the object of replacing yeast. Yeast -is used in baking in order that it may form gas inside the dough and -thus produce a light spongy loaf. Exactly the same gas can be readily -and cheaply produced by the interaction of a carbonate with an acid. -These substances will not react to produce acid as long as they remain -dry, but as soon as they are brought into close contact with each other -by the presence of water, reaction begins and carbon dioxide gas is -formed. These facts are taken advantage of in the manufacture of baking -powders and self-rising flours. Baking powders commonly consist of -ordinary bicarbonate of soda mixed with an acid or an acid salt, such -as tartaric acid, cream of tartar, acid phosphate of lime, or acid -phosphate of potash. One of these latter acid substances is mixed in -proper proportions with the bicarbonate of soda, and the mixture ground -up with powdered starch which serves to dilute the chemicals and to -keep them dry. A small quantity of the baking powder is mixed with the -flour before the water is added to make the dough. The presence of the -water causes the acid and the carbonate to give off gas which, as in -the case of the gas formed by the growth of yeast, fills the dough with -bubbles which expand in the oven and produce light spongy bread. When -using baking powders in place of yeast it must not be forgotten that -gas formation in most cases begins immediately the water is added, and -lasts for a very short time. Consequently the dough must be moulded and -baked at once or the gas will escape. This is not the case, however, -with those powders which are made with cream of tartar, for this -substance does not react with the carbonate to any great extent until -the dough gets warm in the oven. For some purposes it is customary to -use carbonate of ammonia, technically known as volatile, in place of -baking powder. This substance is used alone without any addition of -acid, because it decomposes when heated and forms gas inside the dough. -Sometimes too one or other of the baking powders above described are -added to the flour by the miller, the product being sold as self-rising -flour. Such flour will of course lose its property of self-rising if -allowed to get damp. Occasionally objectionable substances are used in -making baking powders of self-rising flours. Some baking powders for -instance contain alum which is not a desirable addition to any article -of human food. Baking powders and self-rising flours are far more -frequently used by house-wives for making pastry or for other kinds of -domestic cookery than for breadmaking. - -Bread is made on the large scale without the intervention of yeast -by the aeration process, which is carried out as follows. A small -quantity of malt is allowed to soak in a large quantity of water, and -the solution thus obtained is kept warm so that it may ferment. This -charges the solution with gas and at the same time produces other -substances which are supposed to give the bread a good flavour. Such a -solution too retains gas much better than pure water. This solution is -then mixed with a proper proportion of flour inside a closed vessel, -carbon dioxide gas made by the action of acid on a carbonate being -pumped into the vessel whilst the mixing is in progress. The mixing -is of course effected by mechanical means. As soon as the dough is -sufficiently mixed, it is allowed to escape by opening a large tap -at the bottom of the mixing vessel. This it does quite readily being -forced out by the pressure of gas inside. As it comes out portions of -suitable size to make a loaf are cut off. These are at once moulded -into loaves and put into the oven. The gas which they contain expands, -and light well risen bread is produced. This process is especially -suited for wholemeal and other flours containing much offal, which -apparently do not give the best results when submitted to the ordinary -yeast fermentation. - -Before closing this chapter it may be of interest to add a short -account of the sale of bread. Bread is at the present time nominally -sold by weight under acts of Parliament passed about 80 years ago. -That is to say, a seller of bread must provide in his shop scales and -weights which will enable him to weigh the loaves he sells. No doubt -he would be prepared to do so if requested by a customer, in which -case he would probably make up any deficiency in weight which might be -found by adding as a makeweight a slice from another loaf. For this -purpose it is commonly accepted that the ordinary loaf should weigh two -pounds. But in practice this does not occur, for practically the whole -of the bread which is sold in this country is sold from the baker’s -cart, which delivers bread at the houses of customers, and not over -the counter. Customers obviously cannot be expected to wait at their -doors whilst the man in the cart weighs each loaf he is delivering -to them. In actual practice therefore the bread acts, as they are -called, are really a dead letter, and bread is sold by the loaf and -not by weight, though it must be remembered that the loaf has the -reputed weight of two pounds. There are no doubt slight variations -from this weight, but for all practical purposes competition nowadays -is quite as effective a check on the _bona fides_ of the bread seller -as enforced sale by weight would be likely to be. If a baker got the -reputation of selling loaves appreciably under weight his custom would -very soon be transferred to one of his more scrupulous competitors. -Altogether it may be concluded that the present unregulated method of -sale does not work to the serious disadvantage of the consumers. A -little consideration will show that the sale of bread could only be put -on a more scientific basis by the exercise of an enormous amount of -trouble, and the employment of a very numerous and expensive staff. No -doubt the ideally perfect way of regulating the sale of either bread -or any other feeding stuff would be to enact that it should be sold by -weight, and that the seller should be compelled to state the percentage -composition, so that the buyer could calculate the price he was asked -to pay per unit of actual foodstuff. Now bread normally contains 36 -per cent. of water, but this amount varies greatly. A two pound loaf -kept in a dry place may easily lose water by evaporation at the rate of -more than an ounce a day. The baker usually weighs out 2 lbs. 3 ozs. -of dough to make each two pound loaf, and this amount yields a loaf -which weighs in most cases fully two pounds soon after it comes out -of the oven. But if the weather is hot and dry such a loaf may very -well weigh less than two pounds by the time it is delivered to the -consumer. In other words the baker cannot have the weight of the loaves -he sells under complete control. Furthermore the loss in weight when a -loaf gets dry by evaporation is due entirely to loss of water, and does -not decrease the amount of actual foodstuff in the loaf. To sell bread -in loaves guaranteed to contain a definite weight of actual foodstuff -might be justified scientifically, but practically it would entail -so great an expense for the salaries of the inspectors and analysts -required to enforce such a regulation that the idea is quite out of -the question. Practically, therefore, the situation is that it would -be unfair to enforce sale by weight pure and simple for the weight of -a loaf varies according to circumstances which are outside the baker’s -control, and further because the weight of the loaf is no guarantee of -the weight of foodstuff present in it. Nor is it possible to enforce -sale by guarantee of the weight of foodstuff in the loaf, for to do -so would be too troublesome and expensive. Finally the keenness of -competition in the baking trade may be relied on to keep an efficient -check on the interests of the consumer. Quite recently an important -public authority has published the results of weighing several -thousand loaves of bread purchased within its area of administration. -The results show that over half the two pound loaves purchased -were under weight to the extent of five per cent. on the average. -Legislation is understood to be suggested as the result of this report, -in which case it is to be hoped that account will be taken of the fact -that the food value of a loaf depends not only on its weight but also -on the percentage of foodstuffs and water which it contains. - - - - -CHAPTER VII - -THE COMPOSITION OF BREAD - - -Bread is a substance which is made in so many ways that it is quite -useless to attempt to give average figures showing its composition. It -will suffice for the present to assume a certain composition which is -probably not far from the truth. This will serve for a basis on which -to discuss certain generalities as to the food-value of bread. The -causes which produce variation in composition will be discussed later, -together with their effect on the food value as far as information is -available. The following table shows approximately the composition of -ordinary white bread as purchased by most of the population of this -country. - - per cent. - - Water 36 - - Organic substances: - Proteins 10 - Starch 42 - Sugar, etc. 10 - Fat 1 - Fibre ·3 63·3 - - Ash: - Phosphoric acid ·2 - Lime, etc. ·5 ·7 - ------ - 100·0 - -The above table shows that one of the most abundant constituents of -ordinary bread is water. Flour as commonly used for baking, although it -may look and feel quite dry, is by no means free from water. It holds -on the average about one-seventh of its own weight or 14 per cent. In -addition to this rather over one-third of its weight of water or about -35 to 40 per cent. is commonly required to convert ordinary flour into -dough. It follows from this that dough will contain when first it is -mixed somewhere about one-half its weight of water or 50 per cent. -About four per cent. of the weight of the dough is lost in the form -of water by evaporation during the fermentation of the dough before -it is scaled and moulded. Usually 2 lb. 3 oz. of dough will make a -two pound loaf, so that about three ounces of water are evaporated in -the oven, This is about one-tenth the weight of the dough or 10 per -cent. Together with the four per cent. loss by evaporation during the -fermenting period, this makes a loss of water of about 14 per cent., -which, when subtracted from the 50 per cent. originally present in the -dough, leaves about 36 per cent. of water in the bread. As pointed out -in the previous chapter this quantity is by no means constant even in -the same loaf. It varies from hour to hour, falling rapidly if the loaf -is kept in a dry place. - -To turn now to the organic constituents. The most important of these -from the point of view of quantity is starch, in fact this is the -most abundant constituent of ordinary bread. Nor is it in bread only -that starch is abundant. It occurs to the extent of from 50 to 70 per -cent. in all the cereals, grains, wheat, barley, oats, maize, and -rice. Potatoes too contain about 20 per cent. of starch, in fact it -is present in most plants. Starch is a white substance which does not -dissolve in cold water, but when boiled in water swells up and makes, -a paste, which becomes thick and semisolid on cooling. It is this -property which makes starch valuable in the laundry. Starch is composed -of the chemical elements carbon, hydrogen, and oxygen. When heated -in the air it will burn and give out heat, but it does not do so as -readily as does fat or oil. It is this property of burning and giving -out heat which makes starch valuable as a foodstuff. When eaten in the -form of bread, or other article of food, it is first transformed by -the digestive juices of the mouth and intestine into sugar, which is -then absorbed from the intestine into the blood, and thus distributed -to the working parts of the body. Here it is oxidized, not with the -visible flame which is usually associated with burning, but gradually -and slowly, and with the formation of heat. Some of this heat is -required to keep up the temperature of the body. The rest is available -for providing the energy necessary to carry on the movements required -to keep the body alive and in health. Practically speaking therefore -starch in the diet plays the same part as fuel in the steam engine. The -food value of starch can in fact be measured in terms of the quantity -of heat which a known weight of it can give out on burning. This is -done by burning a small pellet of starch in a bomb of compressed -oxygen immersed in a measured volume of water. By means of a delicate -thermometer the rise of temperature of the water is measured, and it -is thus found that one kilogram of starch on burning gives out enough -heat to warm 4·1 kilograms of water through one degree. The quantity of -heat which warms one kilogram of water through one degree is called one -unit of heat or calorie, and the amount of heat given out by burning -one kilogram of any substance is called its heat of combustion or -fuel-value. Thus the heat of combustion or fuel-value of starch is 4·1 -calories. - -Sugar has much the same food-value as starch, in fact starch is readily -changed into sugar by the digestive juices of the alimentary canal or -by the ferments formed in germinating seeds. From the point of view -of food-value sugar may be regarded as digested starch. Like starch, -sugar is composed of the elements carbon, hydrogen, and oxygen. Like -starch too its value in nutrition is determined by the amount of heat -it can give out on burning, and again its heat of combustion or fuel -value 3·9 calories is almost the same as that of starch. It will be -noted that the whole of the 10 per cent. quoted in the table as sugar, -etc., is not sugar. Some of it is a substance called dextrin which is -formed from starch by the excessive heat which falls on the outside of -the loaf in the oven. Starch is readily converted by heat into dextrin, -and this fact is applied in many technical processes. For instance much -of the gum used in the arts is made by heating starch. The outside -of the loaf in the oven gets hot enough for some of the starch to be -converted into dextrin. Dextrin is soluble in water like sugar and so -appears with sugar in the analyses of bread. From the point of view of -food-value this is of no consequence, as dextrin and sugar serve the -same purpose in nutrition, and have almost the same value as each other -and as starch. - -Bread always contains a little fat, not as a rule more that one or two -per cent. But although the quantity is small it cannot be neglected -from the dietetic point of view. Fat is composed of the same elements -as starch, dextrin, and sugar, but in different proportions. It -contains far less oxygen than these substances. Consequently it burns -much more readily and gives out much more heat in the process. The heat -of combustion or fuel value of fat is 9·3 calories or 2·3 times greater -than that of starch. Evidently therefore even a small percentage of -fat must materially increase the fuel value of any article of food. -But fat has an important bearing on the nutritive value of bread from -quite another point of view. In the wheat grain the fat is concentrated -in the germ, comparatively little being present in the inner portion -of the grain. Thus the percentage of fat in any kind of bread is on -the whole a very fair indication of the amount of germ which has been -left in the flour from which the loaf was made. It is often contended -nowadays that the germ contains an unknown constituent which plays an -important part in nutrition, quite apart from its fuel-value. On this -supposition the presence of much fat in a sample of bread indicates the -presence of much germ, and presumably therefore much of this mysterious -constituent which is supposed to endow such bread with a special value -in the nutrition particularly of young children. This question will be -discussed carefully in a later chapter. - -White bread contains a very small percentage of what is called by -analysts fibre. The quantity of this substance in a food is estimated -by the analyst by weighing the residue which remains undigested when a -known weight of the food is submitted to a series of chemical processes -designed to imitate as closely as may be the action of the various -digestive juices of the alimentary canal. Theoretically, therefore, -it is intended to represent the amount of indigestible matter present -in the food in question. Practically it does not achieve this result -for some of it undoubtedly disappears during the passage of the -food through the body. It is doubtful however if the portion which -disappears has any definite nutritive value. That part of the fibre -which escapes digestion and is voided in the excrement cannot possibly -contribute to the nutrition of the body. Nevertheless it exerts a -certain effect on the well-being of the consumer, for the presence of -a certain amount of indigestible material stimulates the lower part of -the large intestine and thus conduces to regularity in the excretion -of waste matters, a fact of considerable importance in many cases. -The amount of fibre is an index of the amount of indigestible matter -in a food. In white bread it is small. In brown breads which contain -considerable quantities of the husk of the wheat grain it may be -present to the extent of two or three per cent. Such breads therefore -will contain much indigestible matter, but they will possess laxative -properties which make them valuable in some cases. - -We have left to the last the two constituents which at the present time -possess perhaps the greatest interest and importance, the proteins -and the ash. The proteins of bread consist of several substances, the -differences between which, for the present purpose, may be neglected, -and we may assume that for all practical purposes the proteins of bread -consist of one substance only, namely gluten. The importance of gluten -in conferring on wheat flour the property of making light spongy loaves -has already been insisted upon. No doubt this property of gluten has a -certain indirect bearing on the nutritive value of bread by increasing -its palatability. But gluten being a protein has a direct and special -part to play in nutrition, which is perhaps best illustrated by -following one step further the comparison between the animal body and -a steam engine. It has been pointed out that starch, sugar, and fat -play the same part in the body as does the fuel in a steam engine. But -an engine cannot continue running very long on fuel alone. Its working -parts require renewing as they wear away, and coal is no use for this -purpose. Metal parts must be renewed with metal. In much the same way -the working parts of the animal body wear away, and must be renewed -with the stuff of which they are made. Now the muscles, nerves, glands -and other working parts of the body are made of protein, and they can -only be renewed with protein. Consequently protein must be supplied in -the diet in amount sufficient to make good from day to day the wear and -tear of the working parts of the body. It is for this reason that the -protein of bread possesses special interest and importance. - -Protein like starch, sugar, and fat contains the elements carbon, -hydrogen, and oxygen, but it differs from them in containing also -a large proportion of the element nitrogen, which may be regarded -as its characteristic constituent. When digested in the stomach and -intestine it is split into a large number of simpler substances known -by chemists under the name of amino-acids. Every animal requires these -amino-acids in certain proportions. From the mixture resulting from -the digestion of the proteins in its diet the amino-acids are absorbed -and utilised by the body in the proportions required. If the proteins -of the diet do not supply the amino-acids in these proportions, it is -obvious that an excessive amount of protein must be provided in order -that the diet may supply enough of that particular amino-acid which -is present in deficient amount, and much of those amino-acids which -are abundantly present must go to waste. This is undesirable for -two reasons. Waste amino-acids are excreted through the kidneys, and -excessive waste throws excessive work on these organs, which may lead -to defective excretion, and thus cause one or other of the numerous -forms of ill health which are associated with this condition. Again, -excessive consumption of protein greatly adds to the cost of the diet, -for protein costs nearly as many shillings per pound as starch or sugar -costs pence. - -These considerations show clearly the wisdom of limiting the amount -of protein in the diet to the smallest amount which will provide for -wear and tear of the working parts. The obvious way to do this is to -take a mixed diet so arranged that the various articles of which the -diet consists contain proteins which are so to speak complementary. -The meaning of this is perhaps best illustrated by a concrete example. -The protein of wheat, gluten, is a peculiar one. On digestion it -splits like other proteins into amino-acids, but these are not present -from the dietetic point of view in well balanced proportions. One -particular amino-acid, called glutaminic acid, preponderates, and -unfortunately this particular acid does not happen to be one which the -animal organism requires in considerable quantity. Other amino-acids -which the animal organism does require in large amounts are deficient -in the mixture of amino-acids yielded by the digestion of the protein -of wheat. It follows, therefore, that to obtain enough of these latter -acids a man feeding only on wheat products would have to eat a quantity -of bread which would supply a great excess of the more abundant -glutaminic acid, which would go to waste with the evil results already -outlined. From this point of view it appears that bread should not -form more than a certain proportion of the diet, and that the rest of -the diet should consist of foods which contain proteins yielding on -digestion little glutaminic acid and much of the other amino-acids in -which the protein of wheat is deficient. Unfortunately information -as to the exact amount of the different amino-acids yielded by the -digestion of the proteins even of many of the common articles of food -is not available. But many workers are investigating these matters, and -the next great advance in the science of dietetics will probably come -along these lines. By almost universal custom certain articles of food -are commonly eaten in association: bread and cheese, eggs and bacon, -are instances. Such customs are usually found to be based on some -underlying principle. The principle in this case may well be that of -complementary proteins. - -The remarks which have been made above on the subject of the _rôle_ -of protein in the animal economy apply to adults in which protein -is required for wear and tear only and not for increase in weight. -They will obviously apply with greatly increased force to the case of -growing children, who require protein not only for wear and tear, but -for the building up of their muscles and other working parts as they -grow and develope. Consequently the diet of children should contain -more protein in proportion to their size than that of adults. For -this reason it is not desirable that bread should form an excessive -proportion of their diet. The bread they eat should be supplemented -with some other food richer in protein. - -The ash of bread although so small in amount cannot be ignored, in -fact it is regarded as of very great importance by modern students -of dietetics. The particular constituent of the ash to which most -importance is attached is phosphoric acid. This substance is a -necessary constituent of the bones and of the brain and nerves of all -animals. It exists too in smaller proportions in other organs. Like -other working parts of the body the bones and the nervous system are -subject to wear and tear, which must be replaced if the body is to -remain in normal health. A certain daily supply of phosphoric acid is -required for this purpose, and proportionally to their size more for -children than for adults. Considerable difference of opinion as to the -exact amount required is expressed by those who have investigated this -question, nor is it even agreed whether all forms of phosphoric acid -are of the same value. There is however a general recognition of the -importance of this constituent of the diet, and the subject is under -investigation in many quarters. - - - - -CHAPTER VIII - -CONCERNING DIFFERENT KINDS OF BREAD - - -The table given in the last chapter states the average composition -of ordinary white bread baked in the form of cottage loaves, and the -remarks on the various constituents of bread in the preceding pages -have for the most part referred to the same material, though many of -them may be taken to refer to bread in general. It will now be of -interest to inquire as to the variation in composition which is found -among the different kinds of bread commonly used in this country. -This enquiry will be most readily conducted by first considering the -possible causes which may affect the composition of bread. - -The variation in the composition of bread is a subject which is taken -up from time to time by the public press, and debated therein with a -great display of interest and some intelligent knowledge. In most of -the press discussions in the past interest has been focussed almost -entirely on the effect of different kinds of milling. The attitude -commonly assumed by the food reform section of the contributors may be -stated shortly as follows: In the days of stone milling a less perfect -separation of flour and bran was effected, and the flour contained -more of the materials situated in the grain near the husk than do the -white flours produced by modern methods of roller milling. Again the -modern roller mills separate the germ from the flour, which the stone -mills fail to do, at any rate so completely. Thus the stone ground -flours contain about 80 per cent. of the grain, whilst the whole of the -flour obtained from the modern roller mill seldom amounts to much more -than about 72 per cent. The extra eight per cent. of flour produced -in the stone mills contains all or nearly all the germ and much of -the material rich in protein which lies immediately under the husk. -Hence the stone ground flour is richer in protein, and in certain -constituents of the germ, than white roller mill flour, and hence again -stone ground flour has a higher nutritive value. Roller mill flour has -nothing to commend it beyond its whiteness. It has been suggested that -millers should adopt the standard custom of producing 80 per cent. of -flour from all the wheat passing through their mills and thus retain -those constituents of the grain which possess specially great nutritive -value. - -It would probably be extremely difficult to produce 80 per cent. of -flour from many kinds of wheat, but for the present this point may -be ignored, whilst we discuss the variation in the actual chemical -composition of the flour produced as at present and on the 80 per cent. -basis. In comparing the chemical composition of different kinds of -flour it is obvious that the flours compared must have been made from -the same lot of wheat, for as will be seen later different wheats vary -greatly in the proportions of protein and other important constituents -which they contain. Unfortunately the number of analyses of different -flours made from the same lots of wheat is small. Perhaps the best -series is that published by Dr Hamill in a recent report of the Local -Government Board. Dr Hamill gives the analyses of five different grades -of flour made at seven mills, each mill using the same blend of wheats -for all the different kinds of flour. Calculating all these analyses -to a basis of 10 per cent. of protein in the grade of flour known as -patents, the figures on the opposite page were obtained, which may be -taken to represent with considerable accuracy the average composition -of the various kinds of flours and offals when made from the same wheat. - - Description of flour Protein Phosphoric acid - or offal per cent. per cent. - - Flours: - Patents 10·0 0·18 - Straight grade, about 70 per cent. 10·6 0·21 - Households 10·9 0·26 - Standard flour, about 80 per cent. 11·0 0·35 - Wholemeal 11·3 0·73 - - Offals: - Germ 24·0 2·22 - Sharps 14·5 1·66 - Bran 13·5 2·50 - -Accepting these figures as showing the relative proportions of protein -and phosphoric acid in different flours as affected by milling only, -other sources of variation having been eliminated by the use of the -same blend of wheat, it appears that the flours of commercially higher -grade undoubtedly do contain somewhat less protein and phosphoric -acid than lower grade or wholemeal flours. Taking the extreme cases -of patents and wholemeal flours, the latter contains one-ninth more -protein and four times more phosphoric acid than the former, provided -both are derived from the same wheat. - -In actual practice, however, it generally happens that the higher -grade flours are made from a blend of wheats containing a considerable -proportion of hard foreign wheats which are rich in nitrogen, whilst -wholemeal and standard flours are usually made from home grown wheats -which are relatively poor in nitrogen. From a number of analyses of -foreign and home grown wheats it appears that the relative proportions -of protein is about 12½ per cent. in the hard foreign wheats as -compared with 10 per cent. in home grown wheats. Thus the presence -of a larger proportion of protein in the hard wheats used in the -blend of wheat for making the higher grade flours must tend to reduce -the difference in protein content between say patents and wholemeal -flours as met with in ordinary practice. Furthermore much of the bread -consumed by that part of the population to whom a few grams per day -of protein is of real importance is, or should be, made, for reasons -of economy, from households flour, and the disparity between this -grade of flour and wholemeal flour is much less than is the case with -patents. It appears, therefore, on examining the facts, that there is -no appreciable difference in the protein content of the ordinary white -flours consumed by the poorer classes of the people and wholemeal flour -or standard flour. - -In the above paragraphs account has been taken only of the total amount -of protein in the various kinds of bread and flour. It is obvious, -however, that the total amount present is not the real index of -food-value. Only that portion of any article of diet which is digested -in the alimentary canal can be absorbed into the blood and carried -thereby to the tissues where it is required to make good wear and tear. -The real food-value must therefore depend not on the total amount of -foodstuff present but on the amount which is digestible. The proportion -of protein which can be digested in the different kinds of bread -has been the subject of careful experiments in America, and lately -in Cambridge. The method of experimenting is arduous and unpleasant. -Several people must exist for a number of days on a diet consisting -chiefly of the kind of bread under investigation, supplemented only by -small quantities of food which are wholly digestible, such as milk, -sugar and butter. During the experimental period the diet is weighed -and its protein content estimated by analysis. The excreta are also -collected and their protein content estimated by analysis, so that -the amount of protein which escapes digestion can be ascertained. -The experiment is then repeated with the same individuals and the -same conditions in every way except that another kind of bread is -substituted for the one used before. From the total amount of protein -consumed in each kind of bread the total amount of protein voided -in the excreta is subtracted, and the difference gives the amount -which has been digested and presumably utilised in the body. From -these figures it is easy to calculate the number of parts of protein -digested for every 100 parts of protein eaten in each kind of bread. -This description will have made evident the unpleasant nature of such -experimental work. Its laboriousness will be understood from the fact -that a series of experiments of this kind carried out at Cambridge last -winter necessitated four people existing for a month on the meagre -diet above mentioned, and entailed over 1000 chemical analyses. - -The following table shows the amounts of protein digested per 100 parts -of protein consumed in bread made from various kinds of flour, as based -on the average of a number of experiments made in America, and in the -experiments at Cambridge above referred to. - - Kind of flour from Percentage of Amount of protein digested - which bread the grain per 100 parts eaten - was made contained in American Cambridge - the flour experiments experiments - - Patents 36 -- 89 - Straight grade 70 89 -- - Standard 80 81 86 - Brown 88 -- 80 - Brown 92 -- 77 - Wholemeal 100 76 -- - -The American and the Cambridge figures agree very well with each other, -and this gives confidence in the reliability of the results. It appears -to be quite certain therefore that the protein in bread made from the -higher grade flours is very considerably more digestible than that -contained in bread made from flours containing greater amounts of husk. -The percentages following the names of the various grades of flour in -the first column of the table indicate approximately the proportion -of the whole grain which went into the flour to which the figure is -attached. Looking down these figures it appears that the digestibility -of the protein decreases as more and more of the grain is included in -the flour. It follows, therefore, that whilst by leaving more and more -of the grain in the flour we increase the percentage of protein in the -flour, and consequently in the bread, at the same time we decrease -the digestibility of the protein. Apparently, too, this decrease in -digestibility is proportionally greater than the increase in protein -content, and it follows therefore that breads made from low grade -flours containing much husk will supply less protein which is available -for the use of the body, although they may actually contain slightly -more total protein than the flours of higher grade. - -When all the facts are taken into account it appears that the -contention of the food reformers, that the various breads which contain -those constituents of the grain which lie near the husk are capable of -supplying more protein for the needs of the body than white breads, -cannot be upheld. From statistics collected by the Board of Trade some -few years ago as to the dietary of the working classes it appears that -the diet of workers both in urban and in rural districts contains -about 97 grams of total protein per head per day. This is rather under -than over the commonly accepted standard of 100 grams of protein which -is supposed to be required daily by a healthy man at moderate work. -Consequently a change in his diet which increased the amount of protein -might be expected to be a good change. But the suggested change of -brown bread for white, though it appears to increase the total protein, -turns out on careful examination to fail in its object, for it does not -increase the amount of protein which can be digested. - -From the same statistics it appears that the diet of a working man -includes on the average about 1¼ lb. of bread per day. This amount of -bread contains about 60 grams of protein, or two-thirds of the total -protein of the diet. Now it was pointed out in the last chapter that -the protein of wheat was very rich in glutaminic acid, a constituent -of which animals require comparatively small amounts. It is also -correspondingly poor in certain constituents which are necessary to -animals. Apparently therefore it would be better to increase the diet -in such cases by adding some constituent not made from wheat than by -changing the kind of bread. From the protein point of view, however we -look at it, there appears to be no real reason for substituting one or -other of the various kinds of brown bread for the white bread which -seems to meet the taste of the present day public. - -But important as protein is it is not everything in a diet. As we have -already pointed out the food must not only repair the tissues, it must -also supply fuel. It has been shown also that the fuel-value of a food -can be ascertained by burning a known weight and measuring the number -of units of heat or calories produced. Many samples of bread have been -examined in this way in the laboratories of the American Department of -Agriculture, and it appears from the figures given in their bulletins -that the average fuel value of white bread is about 1·250 calories per -pound, of wholemeal bread only 1·150 calories per pound. These figures -are quite in accord with those which were obtained in Cambridge in -1911, in connection with the digestion experiments already described, -which were also extended so as to include a determination of the -proportion of the energy of the bread which the diet supplied to the -body. The energy or fuel-value of the diet was determined by measuring -the amount of heat given out by burning a known weight of each of -the kinds of bread used in the experiment. The energy which was not -utilised by the body was then determined by measuring how much heat was -given out by burning the excreta corresponding to each kind of bread. -The following table gives side by side the average results obtained in -several such experiments in America and in Cambridge. - -The agreement between the two sets of figures is again on this point -quite satisfactory. It is evident that a greater proportion of the -total energy of white bread can be utilised by the body than is the -case with any of the breads made from flours of lower commercial grades -which contain more husk. In fact it appears that the more of the outer -parts of the grain are left in the flour the smaller is the proportion -of the total energy of the bread which can be utilised. Combining this -conclusion with the fact that brown breads contain on the average less -total energy than white breads, there can be no doubt that white bread -is considerably better than any form of brown bread as a source of -energy for the body. - - Kind of flour from Percentage of Amount of energy utilised - which the bread the grain per 100 units in food - was made contained in American Cambridge - the flour experiments experiments - Patents 36 96 96 - Straight grade 70 92 -- - Standard 80 87 95 - Brown 88 -- 90 - Brown 92 -- 89 - Wholemeal 100 82 -- - -There is one more important substance in respect of which great -superiority is claimed for brown breads, namely phosphoric acid. From -the table on page 122 there can be no doubt that flours containing more -of the outer parts of the grain are very much richer in phosphoric -acid than white flours, and the disparity is so great that after -allowing for the larger proportion of water in brown breads they -must contain far more of this substance than do white breads. In the -Cambridge digestibility experiments quoted above the proportion of the -phosphoric acid digested from the different breads was determined. It -was found that for every 100 parts of phosphoric acid in white bread -only 52 parts were digested, and that in the case of the brown breads -this proportion fell to 41 parts out of 100. Again, as in the case of -protein and energy, the phosphoric acid in white bread is more readily -available to the body than that of brown bread, but in this case the -difference in digestibility is not nearly enough to counterbalance -the much larger proportion of phosphoric acid in the brown bread. -There is no doubt that the body gets more phosphoric acid from brown -bread than from the same quantity of white bread. But before coming -to any practical conclusion it is necessary to know two things, how -much phosphoric acid does a healthy man require per day, and does his -ordinary diet supply enough? - -From the Board of Trade statistics already quoted it appears that, -on the assumption that the average worker eats white bread only, his -average diet contains 2·4 grams of phosphoric acid per day, which would -be raised to 3·2 grams if the white bread were replaced by bread made -from 80 per cent. flour containing ·35 per cent. of phosphoric acid. -Information as to the amount of phosphoric acid required per day by -a healthy man is somewhat scanty, and indicates that the amount is -very variable, but averages about 2½ grams per day. If this is so, -the ordinary diet with white bread provides on the average enough -phosphoric acid. Exceptional individuals may, however, be benefited by -the substitution of brown bread for white, but it would probably be -better even in such cases, for the reasons stated when discussing the -protein question, to raise the phosphorus content of their diet by the -addition of some substance rich in phosphorus but not made from wheat. - -Finally comes the question of the variation in the composition of -bread due to the presence or absence of the germ. The first point in -this connection is to decide whether germ is present in appreciable -proportions in any flour except wholemeal. The germ is a soft moist -substance which flattens much more readily than it grinds. Consequently -it is removed from flour by almost any kind of separation, even when -very coarse sieves are employed. If this contention is correct no flour -except wholemeal should contain any appreciable quantity of germ, and -it is certainly very difficult to demonstrate the presence of actual -germ particles even in 80 per cent. flour. Indirect evidence of the -presence of germ may, however, be obtained as already explained by -estimating by chemical analysis the proportion of fat present in -various flours. The figures for such estimations are given by Dr Hamill -in the report of the Local Government Board already referred to. They -show that the percentages of fat in different grades of flours made -from the same blends of wheat are on the average of seven experiments -as follows: patents flour ·96: household flours 1·25: 80 per cent. -or standard flour 1·42. These figures show that the coarser flours -containing more of the whole grain do contain more germ than the flours -of commercially higher grade, in spite of the fact that it is difficult -to demonstrate its presence under the microscope. - -Remembering, however, that the whole of the germ only amounts to about -1½ per cent. of the grain, it is clear that the presence or absence of -more or less germ cannot appreciably affect the food-value as measured -by protein content or energy-value. It is still open to contention that -the germ may contain some unknown constituent possessing a peculiar -effect on nutrition. Such a state of things can well be imagined in the -light of certain experimental results which have been obtained during -the last few years. - -It has been shown for instance by Dr Hopkins in Cambridge, and his -results have been confirmed at the Carnegie Institute in America, that -young rats fail to thrive on a diet composed of suitable amounts of -purified protein, fat, starch, and ash, but that they thrive and grow -normally on such a diet if there is added a trace of milk or other -fresh animal or vegetable substance far too small to influence either -the protein content or the energy-value. Another case in point is the -discovery that the disease known as beri beri, which is caused by a -diet consisting almost exclusively of rice from which the husk has been -removed, can be cured almost at once by the administration of very -small doses of a constituent existing in minute quantities in rice -husk. The suggestion is that high grade flours, like polished rice, may -fail to provide some substance which is necessary for healthy growth, -a substance which is removed in the germ or husk when such flours are -purified, and which is present in flours which have not been submitted -to excessive purification. - -The answer is that no class in Great Britain lives on bread -exclusively. Bread appears from the government statistics already -quoted to form only about half the diet of the workers of the country. -Their diet includes also some milk, meat, and vegetables, and such -substances, according to Dr Hopkins’ experiments, certainly contain the -substance, whatever it may be, that is missing from the artificial diet -on which his young rats failed to thrive. - -One last point. It will have been noticed in the figures given -above that the variations in protein content, digestibility, and -energy-value, between different kinds of bread are usually not -very large. There is, however, one constituent of all breads whose -proportions vary far more widely, namely water. During last summer the -author purchased many samples of bread in and around Cambridge, and -determined the percentage of water in each sample. The samples were all -one day old so that they are comparable with one another. The results -on the whole are a little low, probably because the work was done -during a spell of rather dry weather, when the loaves would lose water -rapidly. - -The average figures are summarised below: - - Percentage - of water - - Cottage loaves made of white flour 31·7 - Tinned loaves made of white flour 32·7 - Small fancy loaves made of white flour 33·7 - Tinned loaves made of “Standard” flour 35·9 - Tinned loaves made of brown or germ flour 40·0 - -The figures speak for themselves. There must obviously be more actual -food in a cottage loaf of white flour containing under 32 per cent. -of water than in any kind of Standard or brown loaf in which the -percentage of water is 36 to 40. It is quite extraordinary that no one -who has organised any of the numerous bread campaigns in the press -appears to have laid hold of the enormous variation in the water -content of different kinds of bread, and its obvious bearing on their -food-value. - - - - -BIBLIOGRAPHY - - -The reader who wishes further information on any of the numerous -subjects connected with the growth, manipulation and composition of -breadstuffs is referred to the following publications, to which among -others the author is much indebted. The list is arranged, as far as -possible, in the same order as the chapters of the book. - - -CHAPTER I. - - The Book of the Rothamsted Experiments, by A. D. Hall. (John - Murray, 1905.) - - The Feeding of Crops and Stock, by A. D. Hall. (John Murray, - 1911.) - - Fertilizers and Manures, by A. D. Hall. (John Murray, 1909.) - - The Soil, by A. D. Hall. (John Murray, 1908.) - - Agriculture and Soils of Kent, Surrey, and Sussex, by A. D. - Hall and E. J. Russell. (Board of Agriculture and Fisheries.) - - Some Characteristics of the Western Prairie Soils of Canada, - by Frank T. Shutt. (_Journal of Agricultural Science_, Vol. - III, p. 335.) - - Dry Farming: its Principles and Practice, by Wm Macdonald. (T. - Werner Laurie.) - - Profitable Clay Farming, by John Prout. (1881.) - - Continuous Corn Growing, by W. A. Prout and J. Augustus - Voelcker. (_Journal of the Royal Agricultural Society of - England_, 1905.) - - -CHAPTER II. - - The Wheat Problem, by Sir W. Crookes. (John Murray, 1899.) - - The Production of Wheat in the British Empire, by A. E. - Humphries. (_Journal of the Royal Society of Arts_, Vol. - LVII, p. 229.) - - Wheat Growing in Canada, the United States, and the Argentine, - by W. P. Rutter. (Adam and Charles Black, 1911.) - - Agricultural Note-Book, by Primrose McConnell. (Crosby, - Lockwood and Son, 1910.) - - -CHAPTER III. - - Agricultural Botany, by J. Percival. (Duckworth and Co., 1900.) - - The Interpretation of the Results of Agricultural Experiments, - by T. B. Wood, and Field Trials and their interpretation, - by A. D. Hall and E. J. Russell. (_Journal of the Board of - Agriculture and Fisheries_, Supplement No. 7, Nov. 1911.) - - Heredity in Plants and Animals, by T. B. Wood and R. C. - Punnett. (_Journal of the Highland and Agricultural Society of - Scotland_, Vol. XX, Fifth Series, 1908.) - - Mendelism, by R. C. Punnett. (Macmillan and Co., 1911.) - - Mendel’s Laws and Wheat Breeding, by R. H. Biffen. (_Journal of - Agricultural Science_, Vol. I, p. 4.) - - Studies in the Inheritance of Disease Resistance, by R. H. - Biffen. (_Journal of Agricultural Science_, Vol. II, - p. 109; Vol. IV, p. 421.) - - The Inheritance of Strength in Wheat, by R. H. Biffen. - (_Journal of Agricultural Science_, Vol. III, p. 86.) - - Variation, Heredity, and Evolution, by R. H. Lock. (John - Murray, 1909.) - - Minnesota Wheat Breeding, by Willet M. Hays and Andrew Boss. - (McGill-Warner Co., St Paul.) - - The Improvement of English Wheat, by A. E. Humphries and R. H. - Biffen. (_Journal of Agricultural Science_, Vol. II, - p. 1.) - - Plant Breeding in Scandinavia, by L. H. Newman. (The Canadian - Seed Growers Association, Ottawa, 1912.) - - -CHAPTERS IV, V, AND VI. - - The Technology of Bread Making, by W. Jago. (Simpkin, Marshall - and Co., 1911.) - - Modern Development of Flour Milling, by A. E. Humphries. - (_Journal of the Royal Society of Arts_, Vol. LV, p. - 109.) - - Home Grown Wheat Committee’s Reports. (59, Mark Lane, London, - E.C.) - - The Chemistry of Strength of Wheat Flour, by T. B. Wood. - (_Journal of Agricultural Science_, Vol. II, pp. 139, - 267.) - - -CHAPTERS VII AND VIII. - - Composition and Food Value of Bread, by T. B. Wood. (_Journal - of the Royal Agricultural Society of England_, 1911.) - - Some Experiments on the Relative Digestibility of White and - Whole-meal Breads, by L. F. Newman, G. W. Robinson, E. T. - Halnan, and H. A. D. Neville. (_Journal of Hygiene_, Vol. - XII, No. 2.) - - Nutritive Value of Bread, by J. M. Hamill. (_Local Government - Board Report_, Cd. 5831.) - - Bleaching and Improving Flour, by J. M. Hamill and G. W. Monier - Williams. (_Local Government Board Report_, Cd. 5613.) - - Diet of Rural and Urban Workers. (_Board of Trade Reports_, Cd. - 1761 and 2337.) - - Bulletins of the U.S.A. Department of Agriculture. (Division - of Chemistry 13; Office of Experiment Stations 21, 52, 67, 85, - 101, 126, 156, 185, 227.) - - - - -INDEX - - - Aerated bread, 104 - - Amino-acids, 116 - - Ash of bread, 119 - - - Baking, 63, 91 - - Baking powders, 102 - - Biffen’s new varieties, 49, 59 - method, 41, 46, 58 - - Bread, amount in diet, 127 - composition of, 109 - variations in, 120 - water in, 135 - - Break rolls, 81 - - Breeding of wheat, 29, 35, 40 - - Burgoyne’s Fife, 59 - - - Climate suitable for wheat, 2, 28 - - Clover as preparation for wheat, 8 - - Colloids, 67 - - Continuous growth of wheat, 7 - - Crookes, Sir W., shortage of nitrogen, 5 - - Cropping power of wheats, 32 - - Cross-breeding, 40 - - - Digestibility of bread, 124 - - Dressing wheat, 16 - - Dry farming, 10 - - - Elements required by wheat, 2 - - Energy-values, 111 - - - Fat in bread, 113 - - Fermentation in dough, 94 - - Fibre, 114 - - Field plots, accuracy of, 32 - - Fife wheat, 47, 57 - - Flour, composition of, 122 - grades of, 88, 122 - self-rising, 102 - - Food-value of various breads, 120 - of starch, etc. in bread, 110 - - Foreign wheat growing, 21 - - Fuel-values, 111 - - Futures, 26 - - - Germ, food-value of, 132 - in milling, 89 - in bread, 114, 132 - - Gluten, 63 - properties of, 68 - - Grades of flour, 88, 122 - of wheat, 23 - - - Home Grown Wheat Committee, 53, 56 - - Hopkins’ work, 132 - - Hybridisation, 40 - - - Improvers, flour, 100 - - Indigestible matter in bread, 114 - - Inheritance in wheat, 41 - - - Johannsen, 37 - - Judging wheats, 60 - - - Lawes and Gilbert, 4 - - Liebig, 3 - - Little Joss wheat, 51 - - - Manuring wheat, 3, 7 - - Markets, home, 16 - foreign, 22, 27 - - Market quotations, 19 - - Mendel’s laws, 40 - - Milling, history of, 74, 77 - effect of, on flour, 122 - - Mineral manures, 3 - - Minnesota experiments, 36 - - - Natural moisture in wheat, 52 - - Nitrogen, cost of, in manures, 4 - fixation, 8 - for wheat, 4 - from air, 6 - scarcity of, 5 - synthetic, 6 - - - Ovens for baking, 99 - - - Patents flour, 88 - - Pedigree in wheat, 39 - - Phosphates in bread, 119 - in diet, 131 - in flour, 70 - - Plots for yield testing, 32 - - Protein, cost of, in diet, 116 - in bread, 115 - - Prout’s system of farming, 7 - - Pure-line theory, 37 - - Purification of flour, 86 - - - Rainfall for wheat, 2 - - Red Fife, 47 - - Reduction rolls, 87 - - Roller mill, 79 - - Rotation of crops, 9 - - Rothamsted experiments, 4 - - Rust-proof wheat, 51 - - - Sale of bread, 105 - of wheat, 16 - - Scaling loaves, 96 - - Selection for cropping power, 35 - - Self-rising flour, 102 - - Separation of flour, 85 - - Semolina, 86 - - Sheep-folding, 10 - - Soils for wheat, 2 - - “Standard” flour, 135 - - Starch in bread, 110 - - Stone mill, 75 - - Strength of flour, cause of, 62 - of flour, test for, 66, 72 - of wheat or flour, 53 - - Strong wheats, characters of, 60 - value of, 59 - - Sugar in bread, 112 - - Synthetic nitrogenous manures, 6 - - - Thrashing wheat, 15 - - Turbidity test for strong wheats, 73 - - - Variety of wheat, choice of, 28 - testing, 32 - - Virgin soils, 5 - - - Water in bread, 109, 135 - - Weak wheats, characters of, 61 - - Weights and measures, 17 - - - Yeast, growth in dough, 94 - - Yield of wheat, conditions of, 28 - - -CAMBRIDGE: PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS - - - - -THE - -CAMBRIDGE MANUALS - -OF SCIENCE AND LITERATURE - -Published by the Cambridge University Press - -GENERAL EDITORS - -P. 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