THE STORY OF A. LOAF OF BREAD The Cambridge Manuals of Science and Literature THE STORY OF A LOAF OF BREAD CAMBRIDGE UNIVERSITY PRESS Eontom: FETTER LANE, E.G. C F. CLAY, MANAGER Oftunfcurflfj: 100, PRINCES STREET ILonUon: H. K. LEWIS, 136, GOWER STREET, W.C. WILLIAM WESLEY & SON, 28, ESSEX STREET, STRAND Berlin: A. ASHER AND CO. ILeipjig: F. A. BROCKHAUS $efo gorfe: G. P. PUTNAM'S SONS Bombajj mt Calcutta: MACMILLAN AND CO., LTD. All rights reserved SIL 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. ?. Putnam's Send I A 4 * 4 I 73* W 7 Cambridge: PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS & 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 inno- vation 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 demonstrat- ing 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 267468 vi PREFACE pursue any investigation which involves the cultiva- tion 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 pro- gress 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. Preface ... PAGE y 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 cultiva- tion, 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 W. L. B. 1 2 THE STORY OF A LOAF OF BREAD [OH. acre of available land was under wheat. As transport facilities increased wheat -growing areas were de- veloped 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, nevfertheless 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 i] WHEAT-GROWING 3 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 con- taining 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' nitro- gen 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 re- quired, 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 12 4 THE STORY OF A LOAF OF BREAD [OH. application to his land as mapure, nitrogen is the most costly. At the present time nitrogen in manures costs sevenpence per pound, whilst a pound of phos- phorus 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 i] WHEAT-GROWING 5 to 21 bushels per acre. Obviously on the Rotham- sted 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 nitro- genous manure. The world's demand for nitrogenous manure is therefore certain to increase. Such con- siderations as these inspired Sir William Crookes' Presidential address to the British Association in 1898, in which he foretold the probability of a nitro- gen 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 6 THE STORY OF A LOAF OF BREAD [OH. 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 am- monia 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 sup- plied 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 re- ferred to. It has already been mentioned that when manured with nitrogen alone the Rothamsted soil produced 21 bushels of wheat per acre. When, how- ever, 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 i] WHEAT-GROWING 7 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. What- ever 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 sub- stances. 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 Hertford- shire. 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 8 THE STORY OF A LOAF OF BREAD [CH. some kind of root crop was grown to give an oppor- tunity 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 re- turn manufacture nitrogen for the use of the host. i] WHEAT-GROWING 9 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 prepara- tions 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 consider- able 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. 10 THE STORY OF A LOAF OF BREAD [CH. 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 phos- phates, 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 nitro- genous 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 i] WHEAT-GROWING 11 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 12 THE STORY OF A LOAF OF BREAD [OH. sowing. Whilst he is waiting for rain he takes ad- vantage 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 I] WHEAT-GROWING 13 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 dis- tributes 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 14 THE STORY OF A LOAF OF BREAD [CH. and mutton. The fluctuations in price of these pro- ducts tend to compensate each other. When corn is cheap, meat may be dear, and vice vers&. 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 popu- lated 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. n] MARKETING 15 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 stilljx) thrash it, dress it,_ sell it, and deliver^!/ to the mill or to the railway station, j 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 16 THE STORY OF A LOAF OF BREAD [OH. 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 im- portance 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 market- ing his corn. In many cases he must sell at once n] MARKETING 17 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 2| 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 W. L. B. 2 18 THE STORY OF A LOAF OF BREAD [OH. 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 n] MARKETING 19 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 7/3 J, 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 : 252-7-100=18/4^. 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 con- tinually make troublesome calculations. The average English farmer is an excellent craftsman. He is un- surpassed, 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 mer- chant, whose business it is to attend to such matters, 22 20 THE STORY OF A LOAF OF BREAD [CH. 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 pre- vailing in his district. If the merchant who bought it happens to be also a miller, as is frequently the case, the Avheat 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 n] MARKETING 21 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 stand- ing where it grew, and there it is subsequently burnt. 22 THE STORY OF A LOAF OF BREAD [CH. 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 Govern- ment 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 fre- quent controversy. n] MARKETING 23 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 24 THE STORY OF A LOAF OF BREAD [CH. 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, Min- neapolis, Duluth, Kansas City, St Louis, and Winni- peg, 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 pre- eminence 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 ii] MARKETING 25 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 arid 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 26 THE STORY OF A LOAF OF BREAD [CH. 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 assump- tion, 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 n] MARKETING 27 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 trans- action 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 insur- ance 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 28 THE STORY OF A LOAF OF BREAD [OH. the farmeris 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 m] THE QUALITY OF WHtfAT 29 in wheat-growing which the farmer has to. decide for himself. The British farmer has no equal as a pro- ducer 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, import- ance of purity of breed. It is only in recent years that the idea has dawned on the agricultural com- munity 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 publi- cation 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 Fig. 1. Typical ears of a few of the many cultivated varieties of wheat CH. in] THE QUALITY OF WHEAT 31 say which was the best. It was even almost im- possible 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. 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 32 THE STORY OF A LOAF OF BREAD [OH. 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 crop- ping 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 in] THE QUALITY OF WHEAT 33 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 determina- tion 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 W, L. B, 3 3 I &0 .2 's "p bp S CH. in] THE QUALITY OF WHEAT 35 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. 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 ex- tremely ingenious mechanical sorting instruments, and have raised strains of seed from the plants show- ing 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 deter- mined 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. 32 36 THE STORY OF A LOAF OF BREAD [OH. 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 in] THE QUALITY OF WHEAT 37 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 riot 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 to- wards 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 38 THE STORY OF A LOAF OF BREAD [OH. 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 in] THE QUALITY OF WHEAT 39 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 subse- quent 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 arid difficult one. Of course anyone may be fortunate enough to drop on a valuable* sport when carefully 40 THE STORY OF A LOAF OF BREAD [OH. 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 creat- ing 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 hybrid- isers 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 destroy- ing, 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 monas- tery, 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. Perhaps the best way of describing the bearing of Mendel's Laws on thfe improvement of wheat is to Ill] THE QUALITY OF WHEAT 41 give an illustration from the work carried out by Biften at Cambridge, dealing at first with simple characters obvious to anyone. In one of his first / Fig. 3. A wheat flower with the chaff opened to show the stamens and the stigmas experiments two varieties of wheat were crossed with each other. The one variety possessed long loose beardless ears, the other short dense bearded ears. 42 THE STORY OF A LOAF OF BREAD [OH. 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. Fertili- sation 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 Ill] THE QUALITY OF WHEAT 43 parent. As soon as the cross-fertilised seeds are ripe they are gathered, and early in the autumn they are :, m 3. Fig. 4. P, P, the two parental types. F lt the first cross. F 2 , 1 6, the types found in the second generation sown. It is almost necessary to sow them and other small quantities of seed wheat in an enclosure 44 THE STORY OF A LOAF OF BREAD [OH. 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 beard- less. T^ie first generation plants were also character- ised 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 62 3 1 Translating this into words, out of every 16 plants in the second generation there were four long eared in] THE QUALITY OF WHEAT 45 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 in- variably 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 inter- mediate 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 pro- duced only short eared offspring, long eal-ed 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 46 THE STORY OF A LOAF OF BREAD [OH. 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 recog- nised 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 ob- serving 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 subse- quent 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. The characters described above are not of any great economic importance. Biffen has shown that in] THE QUALITY OF WHEAT 47 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 resist- ance 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 A *0 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. Con- sequently 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 tem- perature 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. Evi- dently 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 64 THE STORY OF A LOAF OF BREAD [OH. 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 atten- tion 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 sug- gestion has been made that its varying properties are dependent on the varying proportions of these two substances present in different samples. This sugges- tion 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 tex- ture. 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 iv] QUALITY OF WHEAT: MILLER'S VIEW 65 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 pro- vide 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 w. L. B. 5 66 THE STORY OF A LOAF OF BREAD [CH. 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 e.c. is measured out, and into it 2^ 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 I iv] QUALITY OF WHEAT: MILLER'S VIEW 67 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 men- tioned 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 fermenta- tion only about 5 c.c. of gas. Having devised a feasible method of estimating how large a loaf any given flour will make, the pro- blem 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 there- fore 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 52 68 THE STORY OF A LOAF OF BREAD [OH. iv 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 investi- gated, 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. 70 THE STORY OF A LOAF OF BREAD [OH. iv 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 com- paratively 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 phos- phate 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