To be intelligible, I must commence by some very brief remarks on the
tissues of vegetables. There are two sorts distinguished among plants;
some seem of no importance in the phenomena of nutrition; others, on the
contrary, tend to the assimilation of the organic or inorganic components
which should nourish and develop all the parts of the plant. The latter
have a striking analogy with ferments; their composition is almost similar,
and their action is increased or diminished by the same causes.
These tissues, formed in a state of repose in vegetables as in grain, have
special properties; thus the berry possesses a pericarp whose tissues
should remain foreign to the phenomena of germination, and these tissues
show no particularity worthy of remark, but the coating of the embryo,
which should play an active part, possesses, on the contrary, properties
that may be compared to those of ferments. With regard to these ferments,
I must further remark that I have not been able, nor am I yet able, to
express in formula my opinion of the nature of these bodies, but little
known as yet; I have only made use of the language mostly employed, without
wishing to touch on questions raised by the effects of the presence, and
by the more complex effects of living bodies, which exercise analogous
actions.
With these reservations I shall proceed to examine the tissues in the berry
which help toward the germination.
THE EMBRYO (10, see woodcut) is composed of the root of the plant, with
which we have nothing to do here. This root of the plant which is to grow
is embedded in a mass of cells full of fatty bodies. These bodies present
this remarkable particularity, that they contain among their elements
sulphur and phosphorus. When you dehydrate by alcohol 100 grammes of the
embryo of wheat, obtained by the same means as the membrane (a process
indicated later on), this embryo, treated with ether, produces 20 grammes
of oils composed elementarily of hydrogen, oxygen, carbon, azote, sulphur,
and phosphorus. This analysis, made according to the means indicated by M.
Fremy, shows that the fatty bodies of the embryo are composed like those of
the germ of an egg, like those of the brain and of the nervous system of
animals. It is necessary for us to stop an instant at this fact: in the
first place, because it proves that vegetables are designed to form the
phosphoric as well as the nitrogenous and ternary aliments, and finally,
because it indicates how important it is to mix the embryo and its
dependents with the bread in the most complete manner possible, seeing that
a large portion of these phosphoric bodies always become decomposed during
the baking.
COATING OF THE EMBRYO.--This membrane (6), which is only an expansion of
the embryo, surrounds the endosperm; it is composed of beautiful irregular
cubic cells, diminishing according as they come nearer to the embryo. These
cells are composed, first, of the insoluble cellular tissue; second,
of phosphate of chalk and fatty phosphoric bodies; third, of soluble
cerealine. In order to study the composition and the nature of this
tissue, it must be completely isolated, and this result is obtained in the
following manner.
The wheat should be damped with water containing 10 parts in 100 of
alcoholized caustic soda; at the expiration of one hour the envelopes of
the pericarp, and of the testa Nos. 2, 3, 4, 5, should be separated by
friction in a coarse cloth, having been reduced by the action of the alkali
to a pulpy state; each berry should then be opened separately to remove the
portion of the envelope held in the fold of the crease, and then all the
berries divided in two are put into three parts of water charged with
one-hundredth of caustic potash. This liquid dissolves the gluten, divides
the starch, and at the expiration of twenty-four hours the parts of the
berries are kneaded between the fingers, collected in pure water, and
washed until the water issues clear; these membranes with their embryos,
which are often detached by this operation, are cast into water acidulated
with one-hundredth of hydrochloric acid, and at the end of several hours
they should be completely washed. The product obtained consists of
beautiful white membranes, insoluble in alkalies and diluted acids, which
show under the microscope beautiful cells joined in a tissue following the
embryo, with which it has indeed a striking analogy in its properties and
composition. This membrane, exhausted by the alcohol and ether, gives, by
an elementary analysis, hydrogen, oxygen, carbon, and azote. Unfortunately,
under the action of the tests this membrane has been killed, and it no
longer possesses the special properties of active tissues. Among these
properties three may be especially mentioned:
1st. Its resistance to water charged with a mineral salt, such as sea salt
for instance
2d. Its action through its presence.
3d. Its action as a ferment.
The action of saltwater is explained as follows: When the berry is plunged
into pure water it will be observed that the water penetrates in the course
of a few hours to the very center of the endosperm, but if water charged
or saturated with sea salt be used, it will be seen that the liquid
immediately passes through the teguments Nos. 2, 3, 4, and 5, and stops
abruptly before the embryo membrane No. 6, which will remain quite dry and
brittle for several days, the berry remaining all the time in the
water. Should the water penetrate further after several days, it can be
ascertained that the entrance was gained through the part No 10 free of
this tissue, and this notwithstanding the cells are full of fatty bodies.
This membrane alone produces this action, for if the coatings Nos. 2, 3, 4,
and 5 be removed, the resistance to the liquid remains the same, while if
the whole, or a portion of it, be divided, either by friction between two
millstones or by simple incisions, the liquid penetrates the berry within
a few hours. This property is analogous to that of the radicules of roots,
which take up the bodies most suitable for the nourishment of the plant. It
proves, besides, that this membrane, like all those endowed with life, does
not obey more the ordinary laws of permeability than those of chemical
affinity, and this property can be turned to advantage in the preservation
of grain in decortication and grinding.
To determine the action of this tissue through its presence, take 100
grammes of wheat, wash it and remove the first coating by decortication;
then immerse it for several hours in lukewarm water, and dry afterwards in
an ordinary temperature. It should then be reduced in a small coffee mill,
the flour and middlings separated by sifting and the bran repassed through
a machine that will crush it without breaking it; then dress it again, and
repeat the operation six times at least. The bran now obtained is composed
of the embryous membrane, a little flour adhering to it, and some traces
of the teguments Nos. 2, 3, 4, and 5. This coarse tissue-weighs about 14
grammes, and to determine its action through its presence, place it in 200
grammes of water at a temperature of 86°; afterwards press it. The liquid
that escapes contains chiefly the flour and cerealine. Filter this liquid,
and put it in a test glass marked No. 1, which will serve to determine the
action of the cerealine.
The bran should now be washed until the water issues pure, and until it
shows no bluish color when iodized water and sulphuric acid are added; when
the washing is finished the bran swollen by the water is placed under a
press, and the liquid extracted is placed, after being filtered, in a test
tube. This test tube serves to show that all cerealine has been removed
from the blades of the tissue. Finally, these small blades of bran, washed
and pressed, are cast, with 50 grammes of lukewarm water, into a test tube,
marked No. 3; 100 grammes of diluted starch to one-tenth of dry starch
are then added in each test tube, and they are put into a water bath at
a temperature of 104° Fahrenheit, being stirred lightly every fifteen
minutes. At the expiration of an hour, or at the most an hour and a half,
No. 1 glass no longer contains any starch, as it has been converted into
dextrine and glucose by the cerealine, and the iodized water only produces
a purple color. No. 2 glass, with the same addition, produces a bluish
color, and preserves the starch intact, which proves that the bran was well
freed from the cerealine contained. No. 3 glass, like No. 1, shows a purple
coloring, and the liquid only contains, in place of the starch, dextrine
and glucose, _i. e_, the tissue has had the same action as the cerealine
deprived of the tissue, and the cerealine as the tissue freed from
cerealine. The same membrane rewashed can again transform the diluted
starch several times. This action is due to the presence of the embryous
membrane, for after four consecutive operations it still preserves its
original weight. As regards the remains of the other segments, they have
no influence on this phenomenon, for the coating Nos. 2, 3, 4, and 5,
separated by the water and friction, have no action whatever on the diluted
starch. Besides its action through its presence, which is immediate,
the embryous membrane may also act as a ferment, active only after a
development, varying in duration according to the conditions of temperature
and the presence or absence of ferments in acting.
I make a distinction here as is seen, between the action through being
present, and the action of real ferments, but it is not my intention to
approve or disapprove of the different opinions expressed on this subject.
I make use of these expressions only to explain more clearly the phenomena
I have to speak of, for it is our duty to bear in mind that the real
ferments only act after a longer or shorter period of development, while,
on the other hand, the effects through presence are immediate.
I now return to the embryous membrane. Various causes increase or decrease
the action of this tissue, but it may be said in general that all the
agents that kill the embryous membrane will also kill the cerealine. This
was the reason why I at first attributed the production of dark bread
exclusively to the latter ferment, but it was easy to observe that during
the baking, decompositions resulted at over 158° Fah., while the cerealine
was still coagulated, and that bread containing bran, submitted to 212° of
heat, became liquefied in water at 104°. It was now easy to determine
that dark flours, from which the cerealine had been removed by repeated
washings, still produced dark bread. It was at this time, in remembering
my experiences with organic bodies, I determined the properties of the
insoluble tissue, deprived of the soluble cerealine, with analogous
properties, but distinguished not alone by its solid organization and state
of insolubility, but also by its resistance to heat, which acts as on
yeast. There exists, in reality, I repeat, a resemblance between the
embryous membrane and the yeast; they have the same immediate composition;
they are destroyed by the same poisons, deadened by the same temperatures,
annihilated by the same agents, propagated in an analogous manner, and
it might be said that the organic tissues endowed with life are only an
agglomeration of fixed cells of ferments. At all events, when the blades of
the embryous membrane, prepared as already stated, are exposed to a water
bath at 212°, this tissue, in contact with the diluted starch, produces
the same decomposition; the contact, however, should continue two or three
hours in place of one. If, instead of placing these membranes in the water
bath, they are enveloped in two pounds of dough, and this dough put in the
oven, after the baking the washed membranes produce the same results, which
especially proves that this membrane can support a temperature of 212° Fah.
without disorganization. We shall refer to this property in speaking of the
phenomena of panification.
CEREALINE.--The cells composing the embryous membrane contain, as already
stated, the cerealine, but after the germination they contain cerealine and
diastase, that is to say, a portion of the cerealine changed into diastase,
with which it has the greatest analogy. It is known how difficult it is to
isolate and study albuminous substances. The following is the method of
obtaining and studying cerealine. Take the raw embryous membrane, prepared
as stated, steep it for an hour in spirits of wine diluted with twice its
volume of water, and renew this liquid several times until the dextrine,
glucose, coloring matters, etc., have been completely removed. The
membranes should now be pressed and cast into a quantity of water
sufficient to make a fluid paste of them, squeeze out the mixture,
filter the liquid obtained, and this liquid will contain the cerealine
sufficiently pure to be studied in its effects. Its principal properties
are: The liquid evaporated at a low temperature produces an amorphous,
rough mass nearly colorless, and almost entirely soluble in distilled
water; this solution coagulates between 158° and 167° Fah., and the
coagulum is insoluble in acids and weak alkalies; the solution is
precipitated by all diluted acids, by phosphoric acid at all the degrees of
hydration, and even by a current of carbonic acid. All these precipitates
redissolve with an excess of acid, sulphuric acid excepted. Concentrated
sulphuric acid forms an insoluble downy white precipitate, and the
concentrated vegetable acids, with the exception of tannic acid, do not
determine any precipitate. Cerealine coagulated by an acid redissolves in
an excess of the same acid, but it has become dead and has no more action
on the starch. The alkalies do not form any precipitate, but they kill the
cerealine as if it had been precipitated The neutral rennet does not make
any precipitate in a solution of cerealine--5 centigrammes of dry cerealine
transform in twenty-five minutes 10 grammes of starch, reduced to a paste
by 100 grammes of water at 113° Fah. It will be seen that cerealine has a
grand analogy with albumen and legumine, but it is distinguished from them
by the action of the rennet, of the heat of acids, alcohol, and above all
by its property of transforming the starch into glucose and dextrine.
It may be said that some albuminous substances have this property, but it
must be borne in mind that these bodies, like gluten, for example, only
possess it after the commencement of the decomposition. The albuminous
matter approaching nearest to cerealine is the diastase, for it is only a
transformation of the cerealine during the germination, the proof of which
may be had in analyzing the embryous membrane, which shows more diastase
and less cerealine in proportion to the advancement of the germination: it
differs, however, from the diastase by the action of heat, alcohol, etc.
It is seen that in every case the cerealine and the embryous membrane
act together, and in an analogous manner; we shall shortly examine their
effects on the digestion and in the phenomena of panification.
PHOSPHATE OF CALCIUM.--Mr. Payen was the first to make the observation
that the greatest amount of phosphate of chalk is found in the teguments
adjoining the farinaceous or floury mass. This observation is important
from two points of view; in the first place, it shows us that this mineral
aliment, necessary to the life of animals, is rejected from ordinary bread;
and in the next place, it brings a new proof that phosphate of chalk is
found, and ought to be found, in everyplace where there are membranes
susceptible of exercising vital functions among animals as well as
vegetables.
Phosphate of chalk is not in reality (as I wished to prove in another work)
a plastic matter suitable for forming bones, for the bones of infants are
three times more solid than those of old men, which contain three times
as much of it. The quantity of phosphate of chalk necessary to the
constitution of animals is in proportion to the temperature of those
animals, and often in the inverse ratio of the weight of their bones, for
vegetables, although they have no bones, require phosphate of chalk. This
is because this salt is the natural stimulant of living membranes, and the
bony tissue is only a depot of phosphate of chalk, analogous to the adipose
tissue, the fat of which is absorbed when the alimentation coming from the
exterior becomes insufficient. Now, as we know all the parts constituting
the berry of wheat, it will be easy to explain the phenomena of
panification, and to conclude from the present moment that it is not
indifferent to reject from the bread this embryous membrane where the
agents of digestion are found, viz., the phosphoric bodies and the
phosphate of chalk.
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