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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..d7b82bc --- /dev/null +++ b/.gitattributes @@ -0,0 +1,4 @@ +*.txt text eol=lf +*.htm text eol=lf +*.html text eol=lf +*.md text eol=lf diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..0a8efbc --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #52824 (https://www.gutenberg.org/ebooks/52824) 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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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.) - - - - - - -</pre> - - -<div id="coverpage"> -<img src="images/cover.jpg" alt="" /> -</div> - -<p><span class="pagenum" id="Page_i">i</span></p> - -<h1> -<span class="x-large">The Cambridge Manuals of Science and -Literature</span><br /> -<br /> -THE STORY OF A LOAF OF BREAD<br /> -<span class="pagenum" id="Page_ii">ii</span><br /> - -<span class="large table">CAMBRIDGE UNIVERSITY PRESS<br /> - -<span class="antiqua">London:</span> FETTER LANE, E.C.<br /> - -C. F. CLAY, <span class="smcap">Manager</span></span><br /> -<br /> - -<img src="images/i_002.jpg" alt="" /><br /> - -<br /> -<span class="medium table"> -<span class="antiqua">Edinburgh:</span> 100, PRINCES STREET<br /> - -<span class="antiqua">London:</span> H. K. LEWIS, 136, GOWER STREET, W.C.<br /> - -WILLIAM WESLEY & SON, 28, ESSEX STREET, STRAND<br /> - -<span class="antiqua">Berlin:</span> A. ASHER AND CO.<br /> - -<span class="antiqua">Leipzig:</span> F. A. BROCKHAUS<br /> - -<span class="antiqua">New York:</span> G. P. PUTNAM’S SONS<br /> - -<span class="antiqua">Bombay and Calcutta:</span> MACMILLAN AND CO., Ltd.</span><br /> - -<br /> -<span class="copy"><i>All rights reserved</i></span><br /> -<span class="pagenum" id="Page_iii">iii</span></h1> - -<div id="image"> -<img src="images/titlepage.jpg" alt="" /> - -<span class="ph3" id="text"> -THE STORY OF<br /> -A LOAF OF BREAD<br /> - -<span class="small">BY</span><br /> - -T. B. WOOD, M.A.<br /> - -<span class="table small">Drapers Professor of Agriculture<br /> -in the University of Cambridge</span><br /> - -<span class="large">Cambridge:</span><br /> -<span class="table small">at the University Press<br /> - -New York:<br /> -G. P. Putnam’s Sons<br /> - -<br />1913</span><br /> -</span> -</div> - -<p><span class="pagenum" id="Page_iv">iv</span></p> - -<p class="caption"> -<span class="antiqua">Cambridge:</span><br /> -<br /> -PRINTED BY JOHN CLAY, M.A.<br /> -AT THE UNIVERSITY PRESS<br /> -</p> - -<p><i>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</i> -<span class="pagenum" id="Page_v">v</span></p> - -<h2 id="PREFACE">PREFACE</h2> - -<p class="drop"><span class="uppercase">I have</span> 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.</p> - -<p>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 -<span class="pagenum" id="Page_vi">vi</span> -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.</p> - -<p>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.</p> - -<p>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.</p> - -<p class="author"> -T. B. W.</p> - -<p><span class="smcap i2">Gonville and Caius College,</span><br /> -<span class="smcap i4">Cambridge.</span><br /> -<span class="i6"><i>3 December, 1912.</i></span> -<span class="pagenum" id="Page_vii">vii</span></p> - -<h2 id="CONTENTS">CONTENTS</h2> - -<table> - <tr> - <td><small>CHAP.</small></td> - <td></td> - <td><small>PAGE</small></td> - </tr> - <tr> - <td></td> - <td><a href="#PREFACE">Preface</a></td> - <td class="tdrb">v</td> - </tr> - <tr> - <td class="tdr">I.</td> - <td><a href="#CHAPTER_I">Wheat-growing</a></td> - <td class="tdrb">1</td> - </tr> - <tr> - <td class="tdr">II.</td> - <td><a href="#CHAPTER_II">Marketing</a></td> - <td class="tdrb">15</td> - </tr> - <tr> - <td class="tdr">III.</td> - <td><a href="#CHAPTER_III">The quality of wheat</a></td> - <td class="tdrb">27</td> - </tr> - <tr> - <td class="tdr">IV.</td> - <td><a href="#CHAPTER_IV">The quality of wheat from the miller’s point of view</a></td> - <td class="tdrb">51</td> - </tr> - <tr> - <td class="tdr">V.</td> - <td><a href="#CHAPTER_V">The milling of wheat</a></td> - <td class="tdrb">74</td> - </tr> - <tr> - <td class="tdr">VI.</td> - <td><a href="#CHAPTER_VI">Baking</a></td> - <td class="tdrb">91</td> - </tr> - <tr> - <td class="tdr">VII.</td> - <td><a href="#CHAPTER_VII">The composition of bread</a></td> - <td class="tdrb">108</td> - </tr> - <tr> - <td class="tdr">VIII.</td> - <td><a href="#CHAPTER_VIII">Concerning different kinds of bread</a></td> - <td class="tdrb">120</td> - </tr> - <tr> - <td></td> - <td><a href="#BIBLIOGRAPHY">Bibliography</a></td> - <td class="tdrb">136</td> - </tr> - <tr> - <td></td> - <td><a href="#INDEX">Index</a></td> - <td class="tdrb">139</td> - </tr> -</table> - -<p><span class="pagenum" id="Page_viii">viii</span></p> - -<h2 id="LIST_OF_ILLUSTRATIONS">LIST OF ILLUSTRATIONS</h2> - -<table> - <tr> - <td><small>FIG.</small></td> - <td></td> - <td class="tdr"><small>PAGE</small></td> - </tr> - <tr> - <td class="tdr">1.</td> - <td><a href="#FIG_1">Typical ears of wheat</a></td> - <td class="tdrb">30</td> - </tr> - <tr> - <td class="tdr">2.</td> - <td><a href="#FIG_2">Bird-proof enclosure for variety testing</a></td> - <td class="tdrb">34</td> - </tr> - <tr> - <td class="tdr">3.</td> - <td><a href="#FIG_3">A wheat flower to illustrate the method of cross-fertilising</a></td> - <td class="tdrb">41</td> - </tr> - <tr> - <td class="tdr">4.</td> - <td><a href="#FIG_4">Parental types and first and second generation</a></td> - <td class="tdrb">43</td> - </tr> - <tr> - <td class="tdr">5.</td> - <td><a href="#FIG_5">Parent varieties in bird-proof enclosure</a></td> - <td class="tdrb">48</td> - </tr> - <tr> - <td class="tdr">6.</td> - <td><a href="#FIG_6">Testing new varieties in the field</a></td> - <td class="tdrb">50</td> - </tr> - <tr> - <td class="tdr">7.</td> - <td><a href="#FIG_7">Loaves made from Manitoba wheat</a></td> - <td class="tdrb">54</td> - </tr> - <tr> - <td class="tdr">8.</td> - <td><a href="#FIG_8">Loaves made from English wheat</a></td> - <td class="tdrb">54</td> - </tr> - <tr> - <td class="tdr">9.</td> - <td><a href="#FIG_9">Loaves made from Rivet wheat</a></td> - <td class="tdrb">55</td> - </tr> - <tr> - <td class="tdr">10.</td> - <td><a href="#FIG_10">Loaves made from Manitoba wheat, English wheat, and Manitoba-English hybrid, Burgoyne’s Fife</a></td> - <td class="tdrb">59</td> - </tr> - <tr> - <td class="tdr">11.</td> - <td><a href="#FIG_11">Gluten in water and acid</a></td> - <td class="tdrb">69</td> - </tr> - <tr> - <td class="tdr">12.</td> - <td><a href="#FIG_12">Gluten in water containing both acid and salts</a></td> - <td class="tdrb">71</td> - </tr> - <tr> - <td class="tdr">13.</td> - <td><a href="#FIG_13">End view of break rolls</a></td> - <td class="tdrb">81</td> - </tr> - <tr> - <td class="tdr">14.</td> - <td><a href="#FIG_14">Break rolls showing gearing</a></td> - <td class="tdrb">82</td> - </tr> - <tr> - <td class="tdr">15.</td> - <td><a href="#FIG_15">Reduction rolls</a></td> - <td class="tdrb">87</td> - </tr> - <tr> - <td class="tdr">16.</td> - <td><a href="#FIG_16">Baking test: loaves rising in incubator</a></td> - <td class="tdrb">92</td> - </tr> - <tr> - <td class="tdr">17.</td> - <td><a href="#FIG_17">Baking test: loaves leaving the oven</a></td> - <td class="tdrb">93</td> - </tr> -</table> - -<p><span class="pagenum" id="Page_1">1</span></p> - -<p class="ph1">THE STORY OF A LOAF OF BREAD</p> - -<h2 id="CHAPTER_I">CHAPTER I<br /> - -<span class="medium">WHEAT GROWING</span></h2> - -<p>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 -<span class="pagenum" id="Page_2">2</span> -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.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum" id="Page_3">3</span> -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 -<span class="pagenum" id="Page_4">4</span> -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 -<span class="pagenum" id="Page_5">5</span> -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 -<span class="pagenum" id="Page_6">6</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_7">7</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_8">8</span> -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.</p> - -<p>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. -<span class="pagenum" id="Page_9">9</span> -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.</p> - -<p>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. -<span class="pagenum" id="Page_10">10</span> -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 -<span class="pagenum" id="Page_11">11</span> -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.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum" id="Page_12">12</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_13">13</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_14">14</span> -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.</p> - -<p>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. -<span class="pagenum" id="Page_15">15</span></p> - -<h2 id="CHAPTER_II">CHAPTER II<br /> - -<span class="medium">MARKETING</span></h2> - -<p>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.</p> - -<p>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 -<span class="pagenum" id="Page_16">16</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_17">17</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_18">18</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_19">19</span> -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:</p> - -<p class="caption"> -7/3½ x 252 ÷ 100 = 18/4½.<br /> -</p> - -<p>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, -<span class="pagenum" id="Page_20">20</span> -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.</p> - -<p>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.</p> - -<p>We have now followed wheat production in -<span class="pagenum" id="Page_21">21</span> -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.</p> - -<p>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. -<span class="pagenum" id="Page_22">22</span> -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.</p> - -<p>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. -<span class="pagenum" id="Page_23">23</span></p> - -<p>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.</p> - -<p>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.</p> - -<p>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.</p> - -<p>No. 3 Northern Spring Wheat shall be composed -of inferior shrunken spring wheat, and weigh not less -than 54 pounds to the measured bushel.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum" id="Page_24">24</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_25">25</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_26">26</span> -that the sales at Minneapolis are really <i>bona fide</i> -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.</p> - -<p>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 -<span class="pagenum" id="Page_27">27</span> -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.</p> - -<p>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.</p> - -<h2 id="CHAPTER_III">CHAPTER III<br /> - -<span class="medium">THE QUALITY OF WHEAT</span></h2> - -<p>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 -<span class="pagenum" id="Page_28">28</span> -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.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum" id="Page_29">29</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_30">30</span> -<span class="pagenum" id="Page_31">31</span> -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.</p> - -<div id="FIG_1" class="figcenter"> -<img src="images/i_030.jpg" alt="" /> -<p class="caption">Fig. 1. Typical ears of a few of the many cultivated varieties of wheat</p> -</div> - -<p>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 -<span class="pagenum" id="Page_32">32</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_33">33</span> -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.</p> - -<p>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.</p> - -<p>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.</p> - -<p>So far we have confined our discussion to the -standard varieties, and we must now turn our -<span class="pagenum" id="Page_34">34</span> -<span class="pagenum" id="Page_35">35</span> -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.</p> - -<div id="FIG_2" class="figcenter"> -<img src="images/i_034.jpg" alt="" /> -<p class="caption">Fig. 2. Part of bird-proof enclosure containing many small plots for variety testing</p> -</div> - -<p>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. -<span class="pagenum" id="Page_36">36</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_37">37</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_38">38</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_39">39</span> -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 -<span class="pagenum" id="Page_40">40</span> -inspecting his crops, and it appears likely that many -of the most valuable varieties in cultivation have -originated from lucky chances of this kind.</p> - -<p>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.</p> - -<div id="FIG_3" class="figcenter"> -<img src="images/i_041.jpg" alt="" /> -<p class="caption">Fig. 3. A wheat flower with the chaff opened to -show the stamens and the stigmas</p> -</div> - -<p>Perhaps the best way of describing the bearing of -Mendel’s Laws on the improvement of wheat is to -<span class="pagenum" id="Page_41">41</span> -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. -<span class="pagenum" id="Page_42">42</span> -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 -<span class="pagenum" id="Page_43">43</span> -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 -<span class="pagenum" id="Page_44">44</span> -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:</p> - -<table> - <tr> - <th>Ears<br />Long<br />Beardless</th> - <th>Ears<br />Long<br />Bearded</th> - <th>Ears<br />Medium<br />Beardless</th> - <th>Ears<br />Medium<br />Bearded</th> - <th>Ears<br />Short<br />Beardless</th> - <th>Ears<br />Short<br />Bearded</th> - </tr> - <tr> - <td class="tdc">3</td> - <td class="tdc">1</td> - <td class="tdc">6</td> - <td class="tdc">2</td> - <td class="tdc">3</td> - <td class="tdc">1</td> - </tr> -</table> - -<p>Translating this into words, out of every 16 plants in -the second generation there were four long eared -<span class="pagenum" id="Page_45">45</span> -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 -<span class="pagenum" id="Page_46">46</span> -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.</p> - -<div id="FIG_4" class="figcenter"> -<img src="images/i_043.jpg" alt="" /> -<p class="caption">Fig. 4. <i>P</i>, <i>P</i>, the two parental types. <i>F₁</i> the first cross. -<i>F₂</i>, 1-6, the types found in the second generation</p> -</div> - -<p>The characters described above are not of any -great economic importance. Biffen has shown that -<span class="pagenum" id="Page_47">47</span> -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 -<span class="pagenum" id="Page_48">48</span> -<span class="pagenum" id="Page_49">49</span> -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 -<span class="pagenum" id="Page_50">50</span> -<span class="pagenum" id="Page_51">51</span> -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.</p> - -<div id="FIG_5" class="figcenter"> -<img src="images/i_048.jpg" alt="" /> -<p class="caption">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</p> -</div> - -<div id="FIG_6" class="figcenter"> -<img src="images/i_050.jpg" alt="" /> -<p class="hang">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</p> -</div> - -<h2 id="CHAPTER_IV">CHAPTER IV<br /> - -<span class="medium">THE QUALITY OF WHEAT FROM THE MILLER’S -POINT OF VIEW</span></h2> - -<p>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. -<span class="pagenum" id="Page_52">52</span></p> - -<p>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.</p> - -<p>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 -<span class="pagenum" id="Page_53">53</span> -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<i>s.</i> 6<i>d.</i> -to 2<i>s.</i> 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.</p> - -<p>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 -<span class="pagenum" id="Page_54">54</span> -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 -<span class="pagenum" id="Page_55">55</span> -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 -<span class="pagenum" id="Page_56">56</span> -from Rivet flour alone would be practically unsaleable. -Rivet wheat finds a ready sale, however, for -making certain kinds of biscuits.</p> - -<div id="FIG_7" class="figcenter"> -<img src="images/i_054a.jpg" alt="" /> -<p class="caption">Fig. 7. Loaves made from No. 1 Manitoba. Strength 100</p> -</div> - -<div id="FIG_8" class="figcenter"> -<img src="images/i_054b.jpg" alt="" /> -<p class="caption">Fig. 8. Loaves made from average English wheat. Strength 65</p> -</div> - -<div id="FIG_9" class="figcenter"> -<img src="images/i_055.jpg" alt="" /> -<p class="caption">Fig. 9. Loaves made from Rivet wheat. Strength 20</p> -</div> - -<p>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<i>s.</i> 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?</p> - -<p>This question has been definitely answered by -the work of the Home Grown Wheat Committee -<span class="pagenum" id="Page_57">57</span> -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 -<span class="pagenum" id="Page_58">58</span> -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.</p> - -<p>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<i>s.</i> 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<i>s.</i> per quarter, which can usually -be obtained by growing Square Head’s Master, or -some other standard variety.</p> - -<div id="FIG_10" class="figcenter"> -<img src="images/i_059.jpg" alt="" /> -<p class="hang">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</p> -</div> - -<p>It was at this point that Mendel’s discoveries came -to the rescue. Working on the Mendelian lines -<span class="pagenum" id="Page_59">59</span> -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 -<span class="pagenum" id="Page_60">60</span> -foreign strong wheats, that is to say from 4<i>s.</i> to 5<i>s.</i> -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<i>s.</i> 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.</p> - -<p>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 -<span class="pagenum" id="Page_61">61</span> -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.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum" id="Page_62">62</span> -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.</p> - -<p>The search for a rapid and accurate method of -measuring strength has for many years attracted -the attention of investigators. As might be expected -<span class="pagenum" id="Page_63">63</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_64">64</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_65">65</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_66">66</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_67">67</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_68">68</span> -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.</p> - -<p>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. -<span class="pagenum" id="Page_69">69</span></p> - -<div id="FIG_11" class="figcenter"> -<p class="caption">Fig. 11.</p> -<span class="table"> - <span class="trow"> - <span class="tcell w33"> - <img src="images/i_069a.jpg" alt="" /><br /> - Gluten in pure water; - soft, but tough and elastic</span> - <span class="tcell w33"> - <img src="images/i_069b.jpg" alt="" /><br /> - 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</span> - <span class="tcell w33"> - <img src="images/i_069c.jpg" alt="" /><br /> - Gluten in hydrochloric - acid (3 parts in 1000 of - water); very hard and - tough</span> - </span> -</span> -</div> - -<p><span class="pagenum" id="Page_70">70</span></p> - -<p>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).</p> - -<p>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 -<span class="pagenum" id="Page_71">71</span> -<span class="pagenum" id="Page_72">72</span> -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.</p> - -<div id="FIG_12" class="figcenter"> -<p class="caption">Fig. 12.</p> -<span class="table"> - <span class="trow"> - <span class="tcell w33"> - <img src="images/i_071a.jpg" alt="" /><br /> - Gluten in water containing - both acid and phosphate; - very tough and elastic</span> - <span class="tcell"> - <img src="images/i_071b.jpg" alt="" /><br /> - Gluten in water containing both acid and sulphates. - It shows varying degrees of coherence, but is brittle or - “short”</span> - </span> -</span> -</div> - -<p>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. -<span class="pagenum" id="Page_73">73</span> -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. -<span class="pagenum" id="Page_74">74</span> -Other wheats yield solutions of intermediate opacity. -This method is now being tested in connection with -the Cambridge wheat breeding experiments.</p> - -<h2 id="CHAPTER_V">CHAPTER V<br /> - -<span class="medium">THE MILLING OF WHEAT</span></h2> - -<p>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.</p> - -<p>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.</p> - -<p>They gradually developed as civilization progressed -<span class="pagenum" id="Page_75">75</span> -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, -<span class="pagenum" id="Page_76">76</span> -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.</p> - -<p>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. -<span class="pagenum" id="Page_77">77</span></p> - -<p>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.</p> - -<p>In the decades before 1870 when the imports of -<span class="pagenum" id="Page_78">78</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_79">79</span> -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.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum" id="Page_80">80</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_81">81</span> -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.</p> - -<div id="FIG_13" class="figcenter"> -<img src="images/i_081.jpg" alt="" /> -<p class="caption">Fig. 13. First break rolls seen from one end. The ribs can -just be seen where the two rolls touch</p> -</div> - -<p>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 -<span class="pagenum" id="Page_82">82</span> -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 -<span class="pagenum" id="Page_83">83</span> -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.</p> - -<div id="FIG_14" class="figcenter"> -<img src="images/i_082.jpg" alt="" /> -<p class="hang">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</p> -</div> - -<p>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 -<span class="pagenum" id="Page_84">84</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_85">85</span> -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 -<span class="pagenum" id="Page_86">86</span> -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 -<span class="pagenum" id="Page_87">87</span> -flour and offal from the large particles of kernel which -require further grinding.</p> - -<div id="FIG_15" class="figcenter"> -<img src="images/i_087.jpg" alt="" /> -<p class="hang">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</p> -</div> - -<p>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 -<span class="pagenum" id="Page_88">88</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_89">89</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_90">90</span> -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. -<span class="pagenum" id="Page_91">91</span></p> - -<h2 id="CHAPTER_VI">CHAPTER VI<br /> - -<span class="medium">BAKING</span></h2> - -<p>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.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum" id="Page_92">92</span> -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. -<span class="pagenum" id="Page_93">93</span> -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 -<span class="pagenum" id="Page_94">94</span> -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. -<span class="pagenum" id="Page_95">95</span></p> - -<div id="FIG_16" class="figcenter"> -<img src="images/i_092.jpg" alt="" /> -<p class="hang">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</p> -</div> - -<div id="FIG_17" class="figcenter"> -<img src="images/i_093.jpg" alt="" /> -<p class="hang">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</p> -</div> - -<p>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.</p> - -<p>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 -<span class="pagenum" id="Page_96">96</span> -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.</p> - -<p>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.</p> - -<p>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. -<span class="pagenum" id="Page_97">97</span> -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 -<span class="pagenum" id="Page_98">98</span> -fermentation is over, so that it is only subjected to -the comparatively slight fermentation which goes on -in the final process of proving.</p> - -<p>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.</p> - -<p>In private houses and in the smaller local bakeries -the whole of the processes described above are carried -<span class="pagenum" id="Page_99">99</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_100">100</span> -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.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum" id="Page_101">101</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_102">102</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_103">103</span> -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 -<span class="pagenum" id="Page_104">104</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_105">105</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_106">106</span> -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 <i>bona -fides</i> 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 -<span class="pagenum" id="Page_107">107</span> -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 -<span class="pagenum" id="Page_108">108</span> -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.</p> - -<h2 id="CHAPTER_VII">CHAPTER VII<br /> - -<span class="medium">THE COMPOSITION OF BREAD</span></h2> - -<p>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. -<span class="pagenum" id="Page_109">109</span></p> - -<table> - <tr> - <td colspan="5" class="tdr">per cent.</td> - </tr> - <tr> - <td>Water</td> - <td colspan="3" class="tdr">36 </td> - </tr> - <tr> - <td>Organic substances:</td> - <td colspan="3"></td> - </tr> - <tr> - <td class="i4">Proteins</td> - <td class="tdr">10 </td> - <td colspan="2"></td> - </tr> - <tr> - <td class="i4">Starch</td> - <td class="tdr">42 </td> - <td colspan="2"></td> - </tr> - <tr> - <td class="i4">Sugar, etc.</td> - <td class="tdr">10 </td> - <td colspan="2"></td> - </tr> - <tr> - <td class="i4">Fat</td> - <td class="tdr">1 </td> - <td colspan="2"></td> - </tr> - <tr> - <td class="i4">Fibre</td> - <td class="tdr">·3</td> - <td></td> - <td class="tdr">63·3</td> - </tr> - <tr> - <td colspan="5">Ash:</td> - </tr> - <tr> - <td class="i4">Phosphoric</td> - <td class="tdr">·2</td> - <td colspan="2"></td> - </tr> - <tr> - <td class="i4">Lime, etc.</td> - <td class="tdr">·5</td> - <td></td> - <td class="tdr">·7</td> - </tr> - <tr> - <td colspan="3"></td> - <td class="bt tdr">100·0</td> - </tr> -</table> - -<p>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 -<span class="pagenum" id="Page_110">110</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_111">111</span> -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 -<span class="pagenum" id="Page_112">112</span> -the heat of combustion or fuel-value of starch is -4·1 calories.</p> - -<p>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. -<span class="pagenum" id="Page_113">113</span></p> - -<p>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 -<span class="pagenum" id="Page_114">114</span> -children. This question will be discussed carefully -in a later chapter.</p> - -<p>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 -<span class="pagenum" id="Page_115">115</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_116">116</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_117">117</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_118">118</span> -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.</p> - -<p>The remarks which have been made above on the -subject of the <i>rôle</i> of protein in the animal economy -apply to adults in which protein is required for wear -<span class="pagenum" id="Page_119">119</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_120">120</span> -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.</p> - -<h2 id="CHAPTER_VIII">CHAPTER VIII<br /> - -<span class="medium">CONCERNING DIFFERENT KINDS OF BREAD</span></h2> - -<p>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.</p> - -<p>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 -<span class="pagenum" id="Page_121">121</span> -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.</p> - -<p>It would probably be extremely difficult to produce -80 per cent. of flour from many kinds of wheat, -<span class="pagenum" id="Page_122">122</span> -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 -<span class="pagenum" id="Page_123">123</span> -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.</p> - -<table> - <tr> - <th>Description of flour<br />or offal</th> - <th>Protein<br />per cent.</th> - <th>Phosphoric acid<br />per cent.</th> - </tr> - <tr> - <td colspan="3">Flours:</td> - </tr> - <tr> - <td class="i4">Patents</td> - <td class="tdc">10·0</td> - <td class="tdc">0·18</td> - </tr> - <tr> - <td class="i4">Straight grade, about 70 per cent.</td> - <td class="tdc">10·6</td> - <td class="tdc">0·21</td> - </tr> - <tr> - <td class="i4">Households</td> - <td class="tdc">10·9</td> - <td class="tdc">0·26</td> - </tr> - <tr> - <td class="i4">Standard flour, about 80 per cent.</td> - <td class="tdc">11·0</td> - <td class="tdc">0·35</td> - </tr> - <tr> - <td class="i4">Wholemeal</td> - <td class="tdc">11·3</td> - <td class="tdc">0·73</td> - </tr> - <tr> - <td colspan="3">Offals:</td> - </tr> - <tr> - <td class="i4">Germ</td> - <td class="tdc">24·0</td> - <td class="tdc">2·22</td> - </tr> - <tr> - <td class="i4">Sharps</td> - <td class="tdc">14·5</td> - <td class="tdc">1·66</td> - </tr> - <tr> - <td class="i4">Bran</td> - <td class="tdc">13·5</td> - <td class="tdc">2·5</td> - </tr> -</table> - -<p>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.</p> - -<p>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 -<span class="pagenum" id="Page_124">124</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_125">125</span> -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 -<span class="pagenum" id="Page_126">126</span> -meagre diet above mentioned, and entailed over -1000 chemical analyses.</p> - -<p>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.</p> - -<table> - <tr> - <th rowspan="2">Kind of flour from<br />which bread<br />was made</th> - <th rowspan="2">Percentage of<br />the grain<br />contained in<br />the flour</th> - <th colspan="2">Amount of protein digested<br />per 100 parts eaten</th> - </tr> - <tr> - <th>American<br />experiments</th> - <th>Cambridge<br />experiments</th> - </tr> - <tr> - <td>Patents</td> - <td class="tdc">36</td> - <td class="tdc"> —</td> - <td class="tdc">89</td> - </tr> - <tr> - <td>Straight grade</td> - <td class="tdc">70</td> - <td class="tdc">89</td> - <td class="tdc">—</td> - </tr> - <tr> - <td>Standard</td> - <td class="tdc">80</td> - <td class="tdc">81</td> - <td class="tdc">86</td> - </tr> - <tr> - <td>Brown</td> - <td class="tdc">88</td> - <td class="tdc">—</td> - <td class="tdc">80</td> - </tr> - <tr> - <td>Brown</td> - <td class="tdc">92</td> - <td class="tdc">—</td> - <td class="tdc">77</td> - </tr> - <tr> - <td>Wholemeal</td> - <td class="tdc">100</td> - <td class="tdc">76</td> - <td class="tdc">—</td> - </tr> -</table> - -<p>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 -<span class="pagenum" id="Page_127">127</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_128">128</span> -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.</p> - -<p>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.</p> - -<p>But important as protein is it is not everything -in a diet. As we have already pointed out the food -<span class="pagenum" id="Page_129">129</span> -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.</p> - -<p>The agreement between the two sets of figures is -again on this point quite satisfactory. It is evident -<span class="pagenum" id="Page_130">130</span> -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.</p> - -<table> - <tr> - <th rowspan="2">Kind of flour from<br />which bread<br />was made</th> - <th rowspan="2">Percentage of<br />the grain<br />contained in<br />the flour</th> - <th colspan="2">Amount of protein digested<br />per 100 parts eaten</th> - </tr> - <tr> - <th>American<br />experiments</th> - <th>Cambridge<br />experiments</th> - </tr> - <tr> - <td>Patents</td> - <td class="tdc">36</td> - <td class="tdc">96</td> - <td class="tdc">96</td> - </tr> - <tr> - <td>Straight grade</td> - <td class="tdc">70</td> - <td class="tdc">92</td> - <td class="tdc">—</td> - </tr> - <tr> - <td>Standard</td> - <td class="tdc">80</td> - <td class="tdc">87</td> - <td class="tdc">95</td> - </tr> - <tr> - <td>Brown</td> - <td class="tdc">88</td> - <td class="tdc">—</td> - <td class="tdc">90</td> - </tr> - <tr> - <td>Brown</td> - <td class="tdc">92</td> - <td class="tdc">—</td> - <td class="tdc">89</td> - </tr> - <tr> - <td>Wholemeal</td> - <td class="tdc">100</td> - <td class="tdc">82</td> - <td class="tdc">—</td> - </tr> -</table> - -<p>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 -<span class="pagenum" id="Page_131">131</span> -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?</p> - -<p>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 -<span class="pagenum" id="Page_132">132</span> -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.</p> - -<p>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 -<span class="pagenum" id="Page_133">133</span> -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.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum" id="Page_134">134</span> -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.</p> - -<p>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.</p> - -<p>One last point. It will have been noticed in the -figures given above that the variations in protein -content, digestibility, and energy-value, between -<span class="pagenum" id="Page_135">135</span> -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.</p> - -<p>The average figures are summarised below:</p> - -<table> - <tr> - <th></th> - <th>Percentage<br />of water</th> - </tr> - <tr> - <td>Cottage loaves made of white flour</td> - <td class="tdc">31·7</td> - </tr> - <tr> - <td>Tinned loaves made of white flour</td> - <td class="tdc">32·7</td> - </tr> - <tr> - <td>Small fancy loaves made of white flour</td> - <td class="tdc">33·7</td> - </tr> - <tr> - <td>Tinned loaves made of “Standard” flour</td> - <td class="tdc">35·9</td> - </tr> - <tr> - <td>Tinned loaves made of brown or germ flour</td> - <td class="tdc">40·0</td> - </tr> -</table> - -<p>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. -<span class="pagenum" id="Page_136">136</span></p> - -<h2 id="BIBLIOGRAPHY">BIBLIOGRAPHY</h2> - -<p>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.</p> - -<h3>CHAPTER I.</h3> - -<blockquote> - -<p>The Book of the Rothamsted Experiments, by A. D. Hall. (John -Murray, 1905.)</p> - -<p>The Feeding of Crops and Stock, by A. D. Hall. (John Murray, -1911.)</p> - -<p>Fertilizers and Manures, by A. D. Hall. (John Murray, 1909.)</p> - -<p>The Soil, by A. D. Hall. (John Murray, 1908.)</p> - -<p>Agriculture and Soils of Kent, Surrey, and Sussex, by A. D. Hall and -E. J. Russell. (Board of Agriculture and Fisheries.)</p> - -<p>Some Characteristics of the Western Prairie Soils of Canada, by -Frank T. Shutt. (<i>Journal of Agricultural Science</i>, Vol. <small>III</small>, -p. 335.)</p> - -<p>Dry Farming: its Principles and Practice, by Wm Macdonald. -(T. Werner Laurie.)</p> - -<p>Profitable Clay Farming, by John Prout. (1881.)</p> - -<p>Continuous Corn Growing, by W. A. Prout and J. Augustus Voelcker. -(<i>Journal of the Royal Agricultural Society of England</i>, 1905.)</p></blockquote> - -<h3>CHAPTER II.</h3> - -<blockquote> - -<p>The Wheat Problem, by Sir W. Crookes. (John Murray, 1899.)</p> - -<p>The Production of Wheat in the British Empire, by A. E. Humphries. -(<i>Journal of the Royal Society of Arts</i>, Vol. <small>LVII</small>, p. 229.)</p> - -<p>Wheat Growing in Canada, the United States, and the Argentine, -by W. P. Rutter. (Adam and Charles Black, 1911.)</p> - -<p>Agricultural Note-Book, by Primrose McConnell. (Crosby, Lockwood -and Son, 1910.)</p></blockquote> -<p><span class="pagenum" id="Page_137">137</span></p> - -<h3>CHAPTER III.</h3> - -<blockquote> - -<p>Agricultural Botany, by J. Percival. (Duckworth and Co., 1900.)</p> - -<p>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. (<i>Journal of the Board of -Agriculture and Fisheries</i>, Supplement No. 7, Nov. 1911.)</p> - -<p>Heredity in Plants and Animals, by T. B. Wood and R. C. Punnett. -(<i>Journal of the Highland and Agricultural Society of Scotland</i>, -Vol. <small>XX</small>, Fifth Series, 1908.)</p> - -<p>Mendelism, by R. C. Punnett. (Macmillan and Co., 1911.)</p> - -<p>Mendel’s Laws and Wheat Breeding, by R. H. Biffen. (<i>Journal of -Agricultural Science</i>, Vol. <small>I</small>, p. 4.)</p> - -<p>Studies in the Inheritance of Disease Resistance, by R. H. Biffen. -(<i>Journal of Agricultural Science</i>, Vol. <small>II</small>, p. 109; Vol. <small>IV</small>, p. 421.)</p> - -<p>The Inheritance of Strength in Wheat, by R. H. Biffen. (<i>Journal of -Agricultural Science</i>, Vol. <small>III</small>, p. 86.)</p> - -<p>Variation, Heredity, and Evolution, by R. H. Lock. (John Murray, -1909.)</p> - -<p>Minnesota Wheat Breeding, by Willet M. Hays and Andrew Boss. -(McGill-Warner Co., St Paul.)</p> - -<p>The Improvement of English Wheat, by A. E. Humphries and -R. H. Biffen. (<i>Journal of Agricultural Science</i>, Vol. <small>II</small>, p. 1.)</p> - -<p>Plant Breeding in Scandinavia, by L. H. Newman. (The Canadian -Seed Growers Association, Ottawa, 1912.)</p></blockquote> - -<h3>CHAPTERS IV, V, AND VI.</h3> - -<blockquote> - -<p>The Technology of Bread Making, by W. Jago. (Simpkin, Marshall -and Co., 1911.)</p> - -<p>Modern Development of Flour Milling, by A. E. Humphries. (<i>Journal -of the Royal Society of Arts</i>, Vol. <small>LV</small>, p. 109.)</p> - -<p>Home Grown Wheat Committee’s Reports. (59, Mark Lane, London, -E.C.)</p> - -<p>The Chemistry of Strength of Wheat Flour, by T. B. Wood. (<i>Journal -of Agricultural Science</i>, Vol. <small>II</small>, pp. 139, 267.)</p></blockquote> -<p><span class="pagenum" id="Page_138">138</span></p> - -<h3>CHAPTERS VII AND VIII.</h3> - -<blockquote> - -<p>Composition and Food Value of Bread, by T. B. Wood. (<i>Journal of -the Royal Agricultural Society of England</i>, 1911.)</p> - -<p>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. (<i>Journal of Hygiene</i>, Vol. <small>XII</small>, No. 2.)</p> - -<p>Nutritive Value of Bread, by J. M. Hamill. (<i>Local Government -Board Report</i>, Cd. 5831.)</p> - -<p>Bleaching and Improving Flour, by J. M. Hamill and G. W. Monier -Williams. (<i>Local Government Board Report</i>, Cd. 5613.)</p> - -<p>Diet of Rural and Urban Workers. (<i>Board of Trade Reports</i>, Cd. -1761 and 2337.)</p> - -<p>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.)</p></blockquote> - -<p><span class="pagenum" id="Page_139">139</span></p> - -<h2 id="INDEX">INDEX</h2> - -<ul class="index"><li class="ifrst">Aerated bread, <a href="#Page_104">104</a></li> - -<li class="indx">Amino-acids, <a href="#Page_116">116</a></li> - -<li class="indx">Ash of bread, <a href="#Page_119">119</a></li> - -<li class="ifrst">Baking, <a href="#Page_63">63</a>, <a href="#Page_91">91</a></li> - -<li class="indx">Baking powders, <a href="#Page_102">102</a></li> - -<li class="indx">Biffen’s new varieties, <a href="#Page_49">49</a>, <a href="#Page_59">59</a></li> -<li class="isub1">method, <a href="#Page_41">41</a>, <a href="#Page_46">46</a>, <a href="#Page_58">58</a></li> - -<li class="indx">Bread, amount in diet, <a href="#Page_127">127</a></li> -<li class="isub1">composition of, <a href="#Page_109">109</a></li> -<li class="isub1">variations in, <a href="#Page_120">120</a></li> -<li class="isub1">water in, <a href="#Page_135">135</a></li> - -<li class="indx">Break rolls, <a href="#Page_81">81</a></li> - -<li class="indx">Breeding of wheat, <a href="#Page_29">29</a>, <a href="#Page_35">35</a>, <a href="#Page_40">40</a></li> - -<li class="indx">Burgoyne’s Fife, <a href="#Page_59">59</a></li> - -<li class="ifrst">Climate suitable for wheat, <a href="#Page_2">2</a>, <a href="#Page_28">28</a></li> - -<li class="indx">Clover as preparation for wheat, <a href="#Page_8">8</a></li> - -<li class="indx">Colloids, <a href="#Page_67">67</a></li> - -<li class="indx">Continuous growth of wheat, <a href="#Page_7">7</a></li> - -<li class="indx">Crookes, Sir W., shortage of nitrogen, <a href="#Page_5">5</a></li> - -<li class="indx">Cropping power of wheats, <a href="#Page_32">32</a></li> - -<li class="indx">Cross-breeding, <a href="#Page_40">40</a></li> - -<li class="ifrst">Digestibility of bread, <a href="#Page_124">124</a></li> - -<li class="indx">Dressing wheat, <a href="#Page_16">16</a></li> - -<li class="indx">Dry farming, <a href="#Page_10">10</a></li> - -<li class="ifrst">Elements required by wheat, <a href="#Page_2">2</a></li> - -<li class="indx">Energy-values, <a href="#Page_111">111</a></li> - -<li class="ifrst">Fat in bread, <a href="#Page_113">113</a></li> - -<li class="indx">Fermentation in dough, <a href="#Page_94">94</a></li> - -<li class="indx">Fibre, <a href="#Page_114">114</a></li> - -<li class="indx">Field plots, accuracy of, <a href="#Page_32">32</a></li> - -<li class="indx">Fife wheat, <a href="#Page_47">47</a>, <a href="#Page_57">57</a></li> - -<li class="indx">Flour, composition of, <a href="#Page_122">122</a></li> -<li class="isub1">grades of, <a href="#Page_88">88</a>, <a href="#Page_122">122</a></li> -<li class="isub1">self-rising, <a href="#Page_102">102</a></li> - -<li class="indx">Food-value of various breads, <a href="#Page_120">120</a></li> -<li class="isub1">of starch, etc. in bread, <a href="#Page_110">110</a></li> - -<li class="indx">Foreign wheat growing, <a href="#Page_21">21</a></li> - -<li class="indx">Fuel-values, <a href="#Page_111">111</a></li> - -<li class="indx">Futures, <a href="#Page_26">26</a></li> - -<li class="ifrst">Germ, food-value of, <a href="#Page_132">132</a></li> -<li class="isub1">in milling, <a href="#Page_89">89</a></li> -<li class="isub1">in bread, <a href="#Page_114">114</a>, <a href="#Page_132">132</a></li> - -<li class="indx">Gluten, <a href="#Page_63">63</a></li> -<li class="isub1">properties of, <a href="#Page_68">68</a></li> - -<li class="indx">Grades of flour, <a href="#Page_88">88</a>, <a href="#Page_122">122</a></li> -<li class="isub1">of wheat, <a href="#Page_23">23</a></li> - -<li class="ifrst">Home Grown Wheat Committee, <a href="#Page_53">53</a>, <a href="#Page_56">56</a></li> - -<li class="indx">Hopkins’ work, <a href="#Page_132">132</a></li> - -<li class="indx">Hybridisation, <a href="#Page_40">40</a></li> - -<li class="ifrst">Improvers, flour, <a href="#Page_100">100</a></li> - -<li class="indx">Indigestible matter in bread, <a href="#Page_114">114</a></li> - -<li class="indx">Inheritance in wheat, <a href="#Page_41">41</a></li> - -<li class="ifrst">Johannsen, <a href="#Page_37">37</a></li> - -<li class="indx">Judging wheats, <a href="#Page_60">60</a></li> - -<li class="ifrst">Lawes and Gilbert, <a href="#Page_4">4</a></li> - -<li class="indx">Liebig, <a href="#Page_3">3</a></li> - -<li class="indx">Little Joss wheat, <a href="#Page_51">51</a> -<span class="pagenum" id="Page_140">140</span></li> - -<li class="ifrst">Manuring wheat, <a href="#Page_3">3</a>, <a href="#Page_7">7</a></li> - -<li class="indx">Markets, home, <a href="#Page_16">16</a></li> -<li class="isub1">foreign, <a href="#Page_22">22</a>, <a href="#Page_27">27</a></li> - -<li class="indx">Market quotations, <a href="#Page_19">19</a></li> - -<li class="indx">Mendel’s laws, <a href="#Page_40">40</a></li> - -<li class="indx">Milling, history of, <a href="#Page_74">74</a>, <a href="#Page_77">77</a></li> -<li class="isub1">effect of, on flour, <a href="#Page_122">122</a></li> - -<li class="indx">Mineral manures, <a href="#Page_3">3</a></li> - -<li class="indx">Minnesota experiments, <a href="#Page_36">36</a></li> - -<li class="ifrst">Natural moisture in wheat, <a href="#Page_52">52</a></li> - -<li class="indx">Nitrogen, cost of, in manures, <a href="#Page_4">4</a></li> -<li class="isub1">fixation, <a href="#Page_8">8</a></li> -<li class="isub1">for wheat, <a href="#Page_4">4</a></li> -<li class="isub1">from air, <a href="#Page_6">6</a></li> -<li class="isub1">scarcity of, <a href="#Page_5">5</a></li> -<li class="isub1">synthetic, <a href="#Page_6">6</a></li> - -<li class="ifrst">Ovens for baking, <a href="#Page_99">99</a></li> - -<li class="ifrst">Patents flour, <a href="#Page_88">88</a></li> - -<li class="indx">Pedigree in wheat, <a href="#Page_39">39</a></li> - -<li class="indx">Phosphates in bread, <a href="#Page_119">119</a></li> -<li class="isub1">in diet, <a href="#Page_131">131</a></li> -<li class="isub1">in flour, <a href="#Page_70">70</a></li> - -<li class="indx">Plots for yield testing, <a href="#Page_32">32</a></li> - -<li class="indx">Protein, cost of, in diet, <a href="#Page_116">116</a></li> -<li class="isub1">in bread, <a href="#Page_115">115</a></li> - -<li class="indx">Prout’s system of farming, <a href="#Page_7">7</a></li> - -<li class="indx">Pure-line theory, <a href="#Page_37">37</a></li> - -<li class="indx">Purification of flour, <a href="#Page_86">86</a></li> - -<li class="ifrst">Rainfall for wheat, <a href="#Page_2">2</a></li> - -<li class="indx">Red Fife, <a href="#Page_47">47</a></li> - -<li class="indx">Reduction rolls, <a href="#Page_87">87</a></li> - -<li class="indx">Roller mill, <a href="#Page_79">79</a></li> - -<li class="indx">Rotation of crops, <a href="#Page_9">9</a></li> - -<li class="indx">Rothamsted experiments, <a href="#Page_4">4</a></li> - -<li class="indx">Rust-proof wheat, <a href="#Page_51">51</a></li> - -<li class="ifrst">Sale of bread, <a href="#Page_105">105</a></li> -<li class="isub1">of wheat, <a href="#Page_16">16</a></li> - -<li class="indx">Scaling loaves, <a href="#Page_96">96</a></li> - -<li class="indx">Selection for cropping power, <a href="#Page_35">35</a></li> - -<li class="indx">Self-rising flour, <a href="#Page_102">102</a></li> - -<li class="indx">Separation of flour, <a href="#Page_85">85</a></li> - -<li class="indx">Semolina, <a href="#Page_86">86</a></li> - -<li class="indx">Sheep-folding, <a href="#Page_10">10</a></li> - -<li class="indx">Soils for wheat, <a href="#Page_2">2</a></li> - -<li class="indx">“Standard” flour, <a href="#Page_135">135</a></li> - -<li class="indx">Starch in bread, <a href="#Page_110">110</a></li> - -<li class="indx">Stone mill, <a href="#Page_75">75</a></li> - -<li class="indx">Strength of flour, cause of, <a href="#Page_62">62</a></li> -<li class="isub1">of flour, test for, <a href="#Page_66">66</a>, <a href="#Page_72">72</a></li> -<li class="isub1">of wheat or flour, <a href="#Page_53">53</a></li> - -<li class="indx">Strong wheats, characters of, <a href="#Page_60">60</a></li> -<li class="isub1">value of, <a href="#Page_59">59</a></li> - -<li class="indx">Sugar in bread, <a href="#Page_112">112</a></li> - -<li class="indx">Synthetic nitrogenous manures, <a href="#Page_6">6</a></li> - -<li class="ifrst">Thrashing wheat, <a href="#Page_15">15</a></li> - -<li class="indx">Turbidity test for strong wheats, <a href="#Page_73">73</a></li> - -<li class="ifrst">Variety of wheat, choice of, <a href="#Page_28">28</a></li> -<li class="isub1">testing, <a href="#Page_32">32</a></li> - -<li class="indx">Virgin soils, <a href="#Page_5">5</a></li> - -<li class="ifrst">Water in bread, <a href="#Page_109">109</a>, <a href="#Page_135">135</a></li> - -<li class="indx">Weak wheats, characters of, <a href="#Page_61">61</a></li> - -<li class="indx">Weights and measures, <a href="#Page_17">17</a></li> - -<li class="ifrst">Yeast, growth in dough, <a href="#Page_94">94</a></li> - -<li class="indx">Yield of wheat, conditions of, <a href="#Page_28">28</a></li></ul> - -<p class="copy">CAMBRIDGE: PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS -<span class="pagenum" id="Page_141">141</span></p> - -<p class="ph1"><span class="x-large">THE</span><br /> - -CAMBRIDGE MANUALS<br /> - -OF SCIENCE AND LITERATURE<br /> - -<span class="medium">Published by the Cambridge University Press</span><br /> - -<span class="medium">GENERAL EDITORS</span><br /> - -<span class="x-large">P. GILES, Litt.D.</span><br /> - -<span class="small">Master of Emmanuel College</span><br /> - -<span class="medium">and</span><br /> - -<span class="x-large">A. C. SEWARD, M.A., F.R.S.</span><br /> - -<span class="small">Professor of Botany in the University of Cambridge</span><br /> - -<span class="x-large">SIXTY VOLUMES NOW READY</span></p> - -<h3><i>HISTORY AND ARCHAEOLOGY</i></h3> - -<blockquote> - -<p>Ancient Assyria. By Rev. C. H. W. Johns, Litt.D.</p> - -<p>Ancient Babylonia. By Rev. C. H. W. Johns, Litt.D.</p> - -<p>A History of Civilization in Palestine. By Prof. R. A. S. -Macalister, M.A., F.S.A.</p> - -<p>China and the Manchus. By Prof. H. A. Giles, LL.D.</p> - -<p>The Civilization of Ancient Mexico. By Lewis Spence.</p> - -<p>The Vikings. By Prof. Allen Mawer, M.A.</p> - -<p>New Zealand. By the Hon. Sir Robert Stout, K.C.M.G., LL.D., -and J. Logan Stout, LL.B. (N.Z.).</p> - -<p>The Ground Plan of the English Parish Church. By A. -Hamilton Thompson, M.A., F.S.A.</p> - -<p>The Historical Growth of the English Parish Church. By A. -Hamilton Thompson, M.A., F.S.A.</p> - -<p>Brasses. By J. S. M. Ward, B.A., F.R.Hist.S.</p> - -<p>Ancient Stained and Painted Glass. By F. S. Eden.</p></blockquote> - -<h3><i>LITERARY HISTORY</i></h3> - -<blockquote> - -<p>The Early Religious Poetry of the Hebrews. By the Rev. -E. G. King, D.D.</p> - -<p>The Early Religious Poetry of Persia. By the Rev. Prof. J. -Hope Moulton, D.D., D.Theol. (Berlin). -<span class="pagenum" id="Page_142">142</span></p> - -<p>The History of the English Bible. By the Rev. John Brown, -D.D.</p> - -<p>English Dialects from the Eighth Century to the Present Day. -By W. W. Skeat, Litt.D., D.C.L., F.B.A.</p> - -<p>King Arthur in History and Legend. By Prof. W. Lewis -Jones, M.A.</p> - -<p>The Icelandic Sagas. By W. A. Craigie, LL.D.</p> - -<p>Greek Tragedy. By J. T. Sheppard, M.A.</p> - -<p>The Ballad in Literature. By T. F. Henderson.</p> - -<p>Goethe and the Twentieth Century. By Prof. J. G. Robertson, -M.A., Ph.D.</p> - -<p>The Troubadours. By the Rev. H. J. Chaytor, M.A.</p></blockquote> - -<h3><i>PHILOSOPHY AND RELIGION</i></h3> - -<blockquote> - -<p>The Idea of God in Early Religions. By Dr F. B. Jevons.</p> - -<p>Comparative Religion. By Dr F. B. Jevons.</p> - -<p>The Moral Life and Moral Worth. By Prof. Sorley, Litt.D.</p> - -<p>The English Puritans. By the Rev. John Brown, D.D.</p> - -<p>An Historical Account of the Rise and Development of Presbyterianism -in Scotland. By the Rt. Hon. the Lord Balfour -of Burleigh, K.T., G.C.M.G.</p> - -<p>Methodism. By Rev. H. B. Workman, D.Lit.</p></blockquote> - -<h3><i>EDUCATION</i></h3> - -<blockquote> - -<p>Life in the Medieval University. By R. S. Rait, M.A.</p></blockquote> - -<h3><i>ECONOMICS</i></h3> - -<blockquote> - -<p>Cash and Credit. By D. A. Barker, I.C.S.</p></blockquote> - -<h3><i>LAW</i></h3> - -<blockquote> - -<p>The Administration of Justice in Criminal Matters (in England -and Wales). By G. Glover Alexander, M.A., LL.M.</p></blockquote> - -<h3><i>BIOLOGY</i></h3> - -<blockquote> - -<p>The Coming of Evolution. By Prof. J. W. Judd, C.B., F.R.S.</p> - -<p>Heredity in the Light of Recent Research. By L. Doncaster, -M.A.</p> - -<p>Primitive Animals. By Geoffrey Smith, M.A.</p> - -<p>The Individual in the Animal Kingdom. By J. S. Huxley, B.A.</p> - -<p>Life in the Sea. By James Johnstone, B.Sc.</p> - -<p>The Migration of Birds. By T. A. Coward.</p> - -<p>Spiders. By C. Warburton, M.A.</p> - -<p>House Flies. By C. G. Hewitt, D.Sc.</p> - -<p>Earthworms and their Allies. By F. E. Beddard, F.R.S.</p></blockquote> -<p><span class="pagenum" id="Page_143">143</span></p> - -<h3><i>ANTHROPOLOGY</i></h3> - -<blockquote> - -<p>The Wanderings of Peoples. By Dr A. C. Haddon, F.R.S.</p> - -<p>Prehistoric Man. By Dr W. L. H. Duckworth.</p></blockquote> - -<h3><i>GEOLOGY</i></h3> - -<blockquote> - -<p>Rocks and their Origins. By Prof. Grenville A. J. Cole.</p> - -<p>The Work of Rain and Rivers. By T. G. Bonney, Sc.D.</p> - -<p>The Natural History of Coal. By Dr E. A. Newell Arber.</p> - -<p>The Natural History of Clay. By Alfred B. Searle.</p> - -<p>The Origin of Earthquakes. By C. Davison, Sc.D., F.G.S.</p></blockquote> - -<h3><i>BOTANY</i></h3> - -<blockquote> - -<p>Plant-Animals: a Study in Symbiosis. By Prof. F. W. Keeble.</p> - -<p>Plant-Life on Land. By Prof. F. O. Bower, Sc.D., F.R.S.</p> - -<p>Links with the Past in the Plant-World. By Prof. A. C. Seward.</p></blockquote> - -<h3><i>PHYSICS</i></h3> - -<blockquote> - -<p>The Earth. By Prof. J. H. Poynting, F.R.S.</p> - -<p>The Atmosphere. By A. J. Berry, M.A.</p> - -<p>The Physical Basis of Music. By A. Wood, M.A.</p></blockquote> - -<h3><i>PSYCHOLOGY</i></h3> - -<blockquote> - -<p>An Introduction to Experimental Psychology. By Dr C. S. -Myers.</p> - -<p>The Psychology of Insanity. By Bernard Hart, M.D.</p></blockquote> - -<h3><i>INDUSTRIAL AND MECHANICAL SCIENCE</i></h3> - -<blockquote> - -<p>The Modern Locomotive. By C. Edgar Allen, A.M.I.Mech.E.</p> - -<p>The Modern Warship. By E. L. Attwood.</p> - -<p>Aerial Locomotion. By E. H. Harper, M.A., and Allan E. -Ferguson, B.Sc.</p> - -<p>Electricity in Locomotion. By A. G. Whyte, B.Sc.</p> - -<p>The Story of a Loaf of Bread. By Prof. T. B. Wood, M.A.</p> - -<p>Brewing. By A. Chaston Chapman, F.I.C.</p></blockquote> - -<h2>SOME VOLUMES IN PREPARATION</h2> - -<h3><i>HISTORY AND ARCHAEOLOGY</i></h3> - -<blockquote> - -<p>The Aryans. By Prof. M. Winternitz.</p> - -<p>The Peoples of India. By J. D. Anderson.</p> - -<p>Prehistoric Britain. By L. McL. Mann.</p> - -<p>The Balkan Peoples. By J. D. Bourchier.</p> - -<p>The Evolution of Japan. By Prof. J. H. Longford. -<span class="pagenum" id="Page_144">144</span></p> - -<p>The West Indies. By Sir Daniel Morris, K.C.M.G.</p> - -<p>The Royal Navy. By John Leyland.</p> - -<p>Gypsies. By John Sampson.</p> - -<p>English Monasteries. By A. H. Thompson, M.A.</p> - -<p>A Grammar of Heraldry. By W. H. St John Hope, Litt.D.</p> - -<p>Celtic Art. By Joseph Anderson, LL.D.</p></blockquote> - -<h3><i>LITERARY HISTORY</i></h3> - -<blockquote> - -<p>The Book. By H. G. Aldis, M.A.</p> - -<p>Pantomime. By D. L. Murray.</p> - -<p>Folk Song and Dance. By Miss Neal and F. Kitson.</p></blockquote> - -<h3><i>PHILOSOPHY AND RELIGION</i></h3> - -<blockquote> - -<p>The Moral and Political Ideas of Plato. By Mrs A. M. Adam.</p> - -<p>The Beautiful. By Vernon Lee.</p></blockquote> - -<h3><i>ECONOMICS</i></h3> - -<blockquote> - -<p>The Theory of Money. By D. A. Barker.</p> - -<p>Women’s Work. By Miss Constance Smith.</p></blockquote> - -<h3><i>EDUCATION</i></h3> - -<blockquote> - -<p>German School Education. By Prof. K. H. Breul, Litt.D.</p> - -<p>The Old Grammar Schools. By Prof. Foster Watson.</p></blockquote> - -<h3><i>PHYSICS</i></h3> - -<blockquote> - -<p>Beyond the Atom. By Prof. J. Cox.</p> - -<p>The Sun. By Prof. R. A. Sampson.</p> - -<p>Wireless Telegraphy. By C. L. Fortescue, M.A.</p> - -<p>Röntgen Rays. By Prof. W. H. Bragg, F.R.S.</p></blockquote> - -<h3><i>BIOLOGY</i></h3> - -<blockquote> - -<p>Bees and Wasps. By O. H. Latter, M.A.</p> - -<p>The Life-story of Insects. By Prof. G. H. Carpenter.</p> - -<p>The Wanderings of Animals. By H. F. Gadow, M.A., F.R.S.</p></blockquote> - -<h3><i>GEOLOGY</i></h3> - -<blockquote> - -<p>Submerged Forests. By Clement Reid, F.R.S.</p> - -<p>Coast Erosion. By Prof. T. J. Jehu.</p></blockquote> - -<h3><i>INDUSTRIAL AND MECHANICAL SCIENCE</i></h3> - -<blockquote> - -<p>Coal Mining. By T. C. Cantrill.</p> - -<p>Leather. By Prof. H. R. Procter.</p></blockquote> - -<p class="copy">Cambridge University Press<br /> -C. F. Clay, Manager<br /> -London: Fetter Lane, E.C.<br /> -Edinburgh: 100, Princes Street</p> - -<div class="transnote"> -<h3>Transcriber's Note:</h3> - -<p>Page 11, 12. “Olland” defined in 1863 by John Morton thus: -Olland (Nors., Suff.) arable land which has been laid down to clover or -grass, for two years.</p> - -<p>Inconsistent spelling and hyphenation are as in the original.</p> -</div> - - - - - - - - -<pre> - - - - - -End of Project Gutenberg's The Story of a Loaf of Bread, by Thomas Barlow Wood - -*** END OF THIS PROJECT GUTENBERG EBOOK THE STORY OF A LOAF OF BREAD *** - -***** This file should be named 52824-h.htm or 52824-h.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/5/2/8/2/52824/ - -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.) - -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. 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