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<p><span class="pagenum" id="Page_i">i</span></p>

<h1>
<span class="x-large">The Cambridge Manuals of Science and
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<br />
THE STORY OF A LOAF OF BREAD<br />
<span class="pagenum" id="Page_ii">ii</span><br />

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<br />
<span class="copy"><i>All rights reserved</i></span><br />
<span class="pagenum" id="Page_iii">iii</span></h1>

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<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 vers&acirc;. 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 2&frac14; 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 7/3&frac12;, 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">
7/3&frac12; x 252 &divide; 100 = 18/4&frac12;.<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,&mdash;since the
sparrow, which would ruin small plots of any other
variety, seems to dislike Rivet, possibly on account
of its beard,&mdash;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&mdash;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 &pound;6 per acre, as compared
with a return of nearly &pound;8 from 4&frac12; 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&deg; C., of this
100 c.c. is measured out, and into it 2&frac12; 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&deg; 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 1&frac12; 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 1&frac12; 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&mdash;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">&middot;3</td>
    <td></td>
    <td class="tdr">63&middot;3</td>
  </tr>
  <tr>
    <td colspan="5">Ash:</td>
  </tr>
  <tr>
    <td class="i4">Phosphoric</td>
    <td class="tdr">&middot;2</td>
    <td colspan="2"></td>
  </tr>
  <tr>
    <td class="i4">Lime, etc.</td>
    <td class="tdr">&middot;5</td>
    <td></td>
    <td class="tdr">&middot;7</td>
  </tr>
  <tr>
    <td colspan="3"></td>
    <td class="bt tdr">100&middot;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&middot;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&middot;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&middot;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&middot;3 calories
or 2&middot;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>r&ocirc;le</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&middot;0</td>
    <td class="tdc">0&middot;18</td>
  </tr>
  <tr>
    <td class="i4">Straight grade, about 70 per cent.</td>
    <td class="tdc">10&middot;6</td>
    <td class="tdc">0&middot;21</td>
  </tr>
  <tr>
    <td class="i4">Households</td>
    <td class="tdc">10&middot;9</td>
    <td class="tdc">0&middot;26</td>
  </tr>
  <tr>
    <td class="i4">Standard flour, about 80 per cent.</td>
    <td class="tdc">11&middot;0</td>
    <td class="tdc">0&middot;35</td>
  </tr>
  <tr>
    <td class="i4">Wholemeal</td>
    <td class="tdc">11&middot;3</td>
    <td class="tdc">0&middot;73</td>
  </tr>
  <tr>
    <td colspan="3">Offals:</td>
  </tr>
  <tr>
    <td class="i4">Germ</td>
    <td class="tdc">24&middot;0</td>
    <td class="tdc">2&middot;22</td>
  </tr>
  <tr>
    <td class="i4">Sharps</td>
    <td class="tdc">14&middot;5</td>
    <td class="tdc">1&middot;66</td>
  </tr>
  <tr>
    <td class="i4">Bran</td>
    <td class="tdc">13&middot;5</td>
    <td class="tdc">2&middot;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 12&frac12; 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"> &mdash;</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">&mdash;</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">&mdash;</td>
    <td class="tdc">80</td>
  </tr>
  <tr>
    <td>Brown</td>
    <td class="tdc">92</td>
    <td class="tdc">&mdash;</td>
    <td class="tdc">77</td>
  </tr>
  <tr>
    <td>Wholemeal</td>
    <td class="tdc">100</td>
    <td class="tdc">76</td>
    <td class="tdc">&mdash;</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 1&frac14; 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&middot;250 calories per
pound, of wholemeal bread only 1&middot;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">&mdash;</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">&mdash;</td>
    <td class="tdc">90</td>
  </tr>
  <tr>
    <td>Brown</td>
    <td class="tdc">92</td>
    <td class="tdc">&mdash;</td>
    <td class="tdc">89</td>
  </tr>
  <tr>
    <td>Wholemeal</td>
    <td class="tdc">100</td>
    <td class="tdc">82</td>
    <td class="tdc">&mdash;</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&middot;4 grams of phosphoric acid per day, which
would be raised to 3&middot;2 grams if the white bread were
replaced by bread made from 80 per cent. flour containing
&middot;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 2&frac12; 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 &middot;96: household flours 1&middot;25: 80 per cent. or standard
flour 1&middot;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 1&frac12; 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&middot;7</td>
  </tr>
  <tr>
    <td>Tinned loaves made of white flour</td>
    <td class="tdc">32&middot;7</td>
  </tr>
  <tr>
    <td>Small fancy loaves made of white flour</td>
    <td class="tdc">33&middot;7</td>
  </tr>
  <tr>
    <td>Tinned loaves made of “Standard” flour</td>
    <td class="tdc">35&middot;9</td>
  </tr>
  <tr>
    <td>Tinned loaves made of brown or germ flour</td>
    <td class="tdc">40&middot;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>R&ouml;ntgen 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>

<div>*** END OF THE PROJECT GUTENBERG EBOOK 52824 ***</div>
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