Is the same true of the other constituents of plants?Is any atom of matter ever lost?
Is the same true of the other constituents of plants?
Is any atom of matter ever lost?
The same is true of any of the organic or inorganic constituents of plants. They are performing their natural offices, or are lying in the earth, or floating in the atmosphere, ready to be lent toanyof their legitimate uses, sure again to be returned to their starting point.
Thus no atom of matter is ever lost. It may change its place, but it remains for ever as a part of the capital of nature.
FOOTNOTES:[A]Bysaturated, we mean that it contains all that it is capable of holding.
[A]Bysaturated, we mean that it contains all that it is capable of holding.
[A]Bysaturated, we mean that it contains all that it is capable of holding.
What are ashes called?How many kinds of matter are there in the ashes of plants?Into what three classes may they be divided?What takes place when alkalies and acids are brought together?
What are ashes called?
How many kinds of matter are there in the ashes of plants?
Into what three classes may they be divided?
What takes place when alkalies and acids are brought together?
We will now examine the ashes left after burning vegetable substances. This we have called inorganic matter, and it is obtained from the soil. Organic matter, although forming so large a part of the plant, we have seen to consist of four different substances. The inorganic portion, on the contrary, although forming so small a part, consists of no less thannineortendifferent kinds of matter.[B]These we will consider in order. In their relations to agriculture they may be divided intothreeclasses—alkalies,acids, andneutrals.[C]
Is the character of a compound the same as that of its constituents?Give an instance of this.Do neutrals combine with other substances?Name the four alkalies found in the ashes of plants.
Is the character of a compound the same as that of its constituents?
Give an instance of this.
Do neutrals combine with other substances?
Name the four alkalies found in the ashes of plants.
Alkalies and acids are of opposite properties, and when brought together they unite and neutralize each other, forming compounds which are neither alkaline nor acid in their character. Thus, carbonic acid (a gas,) unites with lime—a burning, caustic substance—and forms marble, which is a hard tasteless stone. Alkalies and acids are characterized by their desire to unite with each other, and the compounds thus formed have many and various properties, so that the characters of the constituents give no indication of the character of the compound. For instance, lime causes the gases of animal manure to escape, while sulphate of lime (a compound of sulphuric acid and lime) produces an opposite effect, and prevents their escape.
The substances coming under the signification of neutrals, are less affected by the laws of combination, still they often combine feebly with other substances, and some of the resultant compounds are of great importance to agriculture.
The alkalies which are found in the ashes of plants are four in number; they arepotash,soda,limeandmagnesia.
How may we obtain potash from ashes?What are some of its agricultural uses?
How may we obtain potash from ashes?
What are some of its agricultural uses?
When we pour water over wood ashes it dissolves thepotashwhich they contain, and carries it throughin solution. This solution is calledley, and if it be boiled to dryness it leaves a solid substance from which pure potash may be made. Potash left exposed to the air absorbs carbonic acid and becomes carbonate of potash, orpearlash; if another atom of carbonic acid be added, it becomes super-carbonate of potash, orsalæratus. Potash has many uses in agriculture.
1. It forms a constituent of nearly all plants.
2. It unites with silica (a neutral), and forms a compound which water can dissolve and carry into the roots of plants; thus supplying them with an ingredient which gives them much of their strength.[D]
3. It is a strong agent in the decomposition of vegetable matter, and is thus of much importance in preparing manures.
4. It roughens the smooth round particles of sandy soils, and prevents their compacting, as they are often liable to do.
5. It is also of use in killing certain kinds of insects, and, when artificially applied, in smoothing the bark of fruit trees.
The source from which this and the other inorganic matters required are to be obtained, will be fully considered in the section on manures.
Where is soda found most largely?What is Glauber's salts?What is washing soda?What are some of the uses of lime?
Where is soda found most largely?
What is Glauber's salts?
What is washing soda?
What are some of the uses of lime?
Soda, one of the alkalies contained in the ashes of plants, is very much the same as potash in its agricultural character. Its uses are the same as those of potash—before enumerated. Soda exists very largely in nature, as it forms an important part of common salt, whether in the ocean or in those inland deposits known as rock salt. When combined with sulphuric acid it forms sulphate of soda orGlauber's salts. In combination with carbonic acid, as carbonate of soda, it forms the common washing soda of the shops. It is often necessary to render soils fertile.
Limeis in many ways important in agriculture:
1. It is a constituent of plants and animals.
2. It assists in the decomposition of vegetable matter in the soil.
3. It corrects the acidity[E]of sour soils.
4. As chloride or sulphate of lime it is a good absorbent of fertilizing gases.
How is caustic lime made?How much carbonic acid is thus liberated?How does man resemble Sinbad the sailor?
How is caustic lime made?
How much carbonic acid is thus liberated?
How does man resemble Sinbad the sailor?
In nature it usually exists in the form of carbonate of lime: that is, as marble, limestone, and chalk—these all being of the same composition. In manufacturing caustic (or quick) lime, it is customary to burn the carbonate of lime in a kiln; by this means the carbonic acid is thrown off into the atmosphere and the lime remains in a pure or caustic state. A French chemist states that every cubic yard of limestone that is burned, throws offten thousandcubic yards of carbonic acid, which may be used by plants. This reminds us of the story of Sinbad the sailor, where we read of the immensegeniewho came out of a very small box by the sea-shore, much to the surprise of Sinbad, who could not believe his eyes, until thegeniechanged himself into a cloud of smoke and went into the box again. Sinbad fastened the lid, and thegeniemust have remained there until the box was destroyed.
Now man is very much like Sinbad, he lets the carbonic acid out from the limestone (when it expands and becomes a gas); and then he raises a crop, the leaves of which drink it in and pack the carbon away in a very small compass as vegetable matter. Here it must remain until the plant is destroyed, when it becomes carbonic acid again, and occupies just as much space as ever.
The burning of limestone is a very prolific source of carbonic acid.
What do you know about magnesia?What is phosphoric acid composed of?With what substance does it form its most important compound?
What do you know about magnesia?
What is phosphoric acid composed of?
With what substance does it form its most important compound?
Magnesiais the remaining alkali of vegetable ashes. It is well known as a medicine, both in the form of calcined magnesia, and, when mixed with sulphuric acid, as epsom salts.
Magnesia is necessary to nearly all plants, but too much of it is poisonous, and it should be used with much care, as many soils already contain a sufficient quantity. It is often found in limestone rocks (that class calleddolomites), and the injurious effects of some kinds of lime, as well as the barrenness of soils made from dolomites, may be attributed entirely to the fact that they contain too much magnesia.
Phosphoric acid.—This subject is one of the greatest interest to the farmer. Phosphoric acidis composed of phosphorus and oxygen. The end of a loco-foco match contains phosphorus, and when it is lighted it unites with the oxygen of the atmosphere and forms phosphoric acid; this constitutes the white smoke which is seen for a moment before the sulphur commences burning. Being an acid, this substance has the power of combining with any of the alkalies. Its most important compound is with lime.
Will soils, deficient in phosphate of lime, produce good crops?From what source do plants obtain their phosphorus?
Will soils, deficient in phosphate of lime, produce good crops?
From what source do plants obtain their phosphorus?
Phosphate of limeforms about 65 per cent. of the dry weight of the bones of all animals, and it is all derived from the soil through the medium of plants. As plants are intended as food for animals, nature has provided that they shall not attain their perfection without taking up a supply of phosphate of lime as well as of the other earthy matters; consequently, there are many soils which will not produce good crops, simply because they are deficient in phosphate of lime. It is one of the most important ingredients of manures, and its value is dependent on certain conditions which will be hereafter explained.
Another use of phosphoric acid in the plant is to supply it with a small amount ofphosphorus, which seems to be required in the formation of the seed.
What is sulphuric acid composed of?What is plaster?What is silica?Why is it necessary to the growth of plants?What compounds does it form with alkalies?
What is sulphuric acid composed of?
What is plaster?
What is silica?
Why is it necessary to the growth of plants?
What compounds does it form with alkalies?
Sulphuric acidis important to vegetation and is often needed to render soils fertile. It is composed of sulphur and oxygen, and is made for manufacturing purposes, by burning sulphur. With lime it formssulphate of lime, which is gypsum or 'plaster.' In this form it is often found in nature, and is generally used in agriculture. Other important methods for supplying sulphuric acid will be described hereafter. It givestothe plant a small portion ofsulphur, which is necessary to the formation of some of its parts.
How can you prove its existence in corn stalks?What instance does Liebig give to show its existence in grass?How do we supply silicates?Why does grain lodge?What is the most important compound of chlorine?
How can you prove its existence in corn stalks?
What instance does Liebig give to show its existence in grass?
How do we supply silicates?
Why does grain lodge?
What is the most important compound of chlorine?
This is sand, the base of flint. It is necessary for the growth of all plants, as it gives them much of their strength. In connection with an alkali it constitutes the hard shining surface of corn stalks, straw, etc. Silica unites with the alkalies and forms compounds, such assilicate of potash,silicate of soda, etc., which are soluble in water, and thereforeavailable to plants. If we roughen a corn stalk with sand-paper we may sharpen a knife upon it. This is owing to the hard particles of silica which it contains. Window glass is silicate of potash, rendered insoluble by additions of arsenic and litharge.
Liebig tells us that some persons discovered, between Manheim and Heidelberg in Germany, a mass of melted glass where a hay-stack had been struck by lightning. They supposed it to be a meteor, but chemical analysis showed that it was only the compound of silica and potash which served to strengthen the grass.
There is alwaysenoughsilica in the soil, but it is often necessary to add an alkali to render it available. When grain, etc., lodge or fall down from their own weight, it is altogether probable that they are unable to obtain from the soil a sufficient supply of the soluble silicates, and some form of alkali should be added to the soil to unite with the sand and render it soluble.
Of what use is chloride of lime?What is oxide of iron?What is the difference between theperoxide and theprotoxide of iron?
Of what use is chloride of lime?
What is oxide of iron?
What is the difference between theperoxide and theprotoxide of iron?
Chlorineis an important ingredient of vegetable ashes, and is often required to restore the balance tothe soil. It is not found alone in nature, but is always in combination with other substances. Its most important compound is with sodium, formingchloride of sodium(or common salt). Sodium is the base of soda, and common salt is usually the best source from which to obtain both soda and chlorine. Chlorine unites with lime and formschloride of lime, which is much used to absorb the unpleasant odors of decaying matters, and in this character it is of use in the treatment of manures.
Oxide of iron, one of the constituents of ashes, is common iron rust.Ironitself is naturally of a grayish color, but when exposed to the atmosphere, it readily absorbs oxygen and forms a reddish compound. It is in this form that it usually exists in nature, and many soils as well as the red sandstones are colored by it. It is seldom, if ever, necessary to apply this as a manure, there being usually enough of it in the soil.
This red oxide of iron, of which we have been speaking, is called by chemists theperoxide. There is another compound which contains less oxygen thanthis, and is called theprotoxide of iron, which is poisonous to plants. When it exists in the soil it is necessary to use such means of cultivation as shall expose it to the atmosphere and allow it to take up more oxygen and become the peroxide. The black scales which fly from hot iron when struck by the blacksmith's hammer are protoxide of iron.
Theperoxide of ironis a very good absorbent of ammonia, and consequently, as will be hereafter described, adds to the fertility of the soil.
What can you say of the oxide of manganese?How do you classify the inorganic constituents?
What can you say of the oxide of manganese?
How do you classify the inorganic constituents?
Oxide of Manganese, though often found in small quantities in the ashes of cultivated plants, cannot be considered indispensable.
Having now examined all of the materials from which the ashes of plants are formed,[F]we are enabled to classify them in a simple manner, so that they may be recollected. They are as follows:—
FOOTNOTES:[B]Bromine, iodine, etc., are sometimes detected in particular plants, but need not occupy the attention of the farmer.[C]This classification is not strictly scientific, but it is one which the learner will find it well to adopt. These bodies are called neutrals because they have no decided alkaline or acid character.[D]In some soils thefluoridesundoubtedly supply plants with soluble silicates, asfluoric acidhas the power of dissolving silica. Thus, in Derbyshire (England), where the soil is supplied with fluoric acid, grain is said never to lodge.[E]Sourness.[F]There is reason to suppose thataluminais an essential constituent of many plants.
[B]Bromine, iodine, etc., are sometimes detected in particular plants, but need not occupy the attention of the farmer.
[B]Bromine, iodine, etc., are sometimes detected in particular plants, but need not occupy the attention of the farmer.
[C]This classification is not strictly scientific, but it is one which the learner will find it well to adopt. These bodies are called neutrals because they have no decided alkaline or acid character.
[C]This classification is not strictly scientific, but it is one which the learner will find it well to adopt. These bodies are called neutrals because they have no decided alkaline or acid character.
[D]In some soils thefluoridesundoubtedly supply plants with soluble silicates, asfluoric acidhas the power of dissolving silica. Thus, in Derbyshire (England), where the soil is supplied with fluoric acid, grain is said never to lodge.
[D]In some soils thefluoridesundoubtedly supply plants with soluble silicates, asfluoric acidhas the power of dissolving silica. Thus, in Derbyshire (England), where the soil is supplied with fluoric acid, grain is said never to lodge.
[E]Sourness.
[E]Sourness.
[F]There is reason to suppose thataluminais an essential constituent of many plants.
[F]There is reason to suppose thataluminais an essential constituent of many plants.
Of what does a perfect young plant consist?How must the food of plants be supplied?Can carbon and earthy matter be taken up at separate stages of growth, or must they both be supplied at once?
Of what does a perfect young plant consist?
How must the food of plants be supplied?
Can carbon and earthy matter be taken up at separate stages of growth, or must they both be supplied at once?
Having examined the materials of which plants are made, it becomes necessary to discover how they are put together in the process of growth. Let us therefore suppose a young wheat-plant for instance to be in condition to commence independent growth.
It consists of roots which are located in the soil; leaves which are spread in the air, and a stem which connects the roots and leaves. This stem contains sap vessels (or tubes) which extend from the ends of the roots to the surfaces of the leaves, thus affording a passage for the sap, and consequently allowing the matters taken up to be distributed throughout the plant.
What seems to be nature's law with regard to this?What is the similarity between making a cart and raising a crop?In the growth of a young plant, what operations take place about the same time?
What seems to be nature's law with regard to this?
What is the similarity between making a cart and raising a crop?
In the growth of a young plant, what operations take place about the same time?
It is necessary that the materials of which plants are made should be supplied in certain proportions, and at the same time. For instance, carbon could not be taken up in large quantities by the leaves, unless the roots, at the same time, were receiving from the soil those mineral matters which are necessary to growth. On the other hand, no considerable amount of earthy matter could be appropriated by the roots unless the leaves were obtaining carbon from the air. This same rule holds true with regard to all of the constituents required; Nature seeming to have made it a law that if one of the important ingredients of the plant is absent, the others, though they may be present in sufficient quantities, cannot be used. Thus, if the soil is deficient in potash, and still has sufficient quantities of all of the other ingredients, the plant cannot take up these ingredients, because potash is necessary to its life.
If a farmer wishes to make a cart he prepares his wood and iron, gets them all in the proper condition, and then can very readily put them together. But if he has all of thewoodnecessary and noiron, he cannot make his cart, because bolts, nails and screws are required, and their place cannot be supplied by boards. This serves to illustrate the fact that in raising plants we must give them every thing that they require, or they will not grow at all.
In the case of our young plant the following operations are going on at about the same time.
The leaves are absorbing carbonic acid from the atmosphere, and the roots are drinking in water from the soil.
What becomes of the carbonic acid?How is the sap disposed of?What does it contain?How does the plant obtain its carbon?Its oxygen and hydrogen?Its nitrogen?Its inorganic matter?
What becomes of the carbonic acid?
How is the sap disposed of?
What does it contain?
How does the plant obtain its carbon?
Its oxygen and hydrogen?
Its nitrogen?
Its inorganic matter?
Under the influence of daylight, the carbonic acid is decomposed; its oxygen returned to the atmosphere, and its carbon retained in the plant.
The water taken in by the roots circulates through the sap vessels of the plant, and, from various causes, is drawn up towards the leaves where it is evaporated. This water contains thenitrogenand theinorganic matterrequired by the plant and some carbonic acid, while the water itself consists ofhydrogenandoxygen.
Thus we see that the plant obtains its food in the following manner:—
What changes does the food taken up by the plant undergo?
What changes does the food taken up by the plant undergo?
Many of the chemical changes which take place in the interior of the plant are well understood, but they require too much knowledge of chemistry to be easily comprehended by the young learner, and it is not absolutely essential that they should be understood by the scholar who is merely learning theelementsof the science.
It is sufficient to say that the food taken up by the plant undergoes such changes as are required for its growth; as in animals, where the food taken into the stomach, is digested, and formed into bone, muscle, fat, hair, etc., so in the plant the nutritive portions of the sap are resolved into wood, bark, grain, or some other necessary part.
The results of these changes are of the greatest importance in agriculture, and no person can call himself apractical farmerwho does not thoroughly understand them.
We have hitherto examined what is called theultimatedivision of plants. That is, we have looked at each one of the elements separately, and considered its use in vegetable growth.
Of what do wood, starch and the other vegetable compounds chiefly consist?Are their small ashy parts important?What are these compounds called?Into how many classes may proximate principles be divided?Of what do the first class consist? The second?What vegetable compounds do the first class comprise?
Of what do wood, starch and the other vegetable compounds chiefly consist?
Are their small ashy parts important?
What are these compounds called?
Into how many classes may proximate principles be divided?
Of what do the first class consist? The second?
What vegetable compounds do the first class comprise?
We will now examine another division of plants, called theirproximate division. We know that plants consist of various substances, such as wood, gum, starch, oil, etc., and on examination we shall discover that these substances are composed of the variousorganicandinorganicingredients described in the preceding chapters. They are made up almost entirely oforganicmatter, but their ashy parts, though very small, are (as we shall soon see) sometimes of great importance.
These compounds are calledproximate principles,[G]orvegetable proximates. They may be divided into two classes.
The first class are composed ofcarbon,hydrogen, andoxygen.
The second class contain the same substances andnitrogen.
Are these substances of about the same composition?Can they be artificially changed from one to another?Give an instance of this.Is the ease with which these changes take place important?From what may the first class of proximates be formed?
Are these substances of about the same composition?
Can they be artificially changed from one to another?
Give an instance of this.
Is the ease with which these changes take place important?
From what may the first class of proximates be formed?
The first class (those compounds not containing nitrogen) comprise the wood, starch, gum, sugar, and fatty matter which constitute the greater part of all plants, also the acids which are found in sour fruits, etc. Various as are all of these things in their characters, they are entirely composed of the same ingredients (carbon, hydrogen and oxygen), and usually combined in about thesame proportion. There may be a slight difference in the composition of theirashes, but the organic part is much the same in every case, so much so, that they can often be artificially changed from one to the other.
As an instance of this, it may be recollected by those who attended the Fair of the American Institute, in 1834, that Prof. Mapes exhibited samples of excellent sugar made from the juice of the cornstalk, starch, linen, and woody fibre.
The ease with which these proximates may be changed from one to the other is their most important agricultural feature, and should be clearly understood before proceeding farther. It is one of the fundamental principles on which the growth of both vegetables depends.
The proximates of the first class constitute usually the greater part of all plants, and they are readily formed from the carbonic acid and water which in nature are so plentifully supplied.
Why are those of the second class particularly important to farmers?What is the general name under which they are known?What is the protein of wheat called?Why is flour containing much gluten preferred by bakers?Can protein be formed without nitrogen?If plants were allowed to complete their growth without a supply of this ingredient, what would be the result?
Why are those of the second class particularly important to farmers?
What is the general name under which they are known?
What is the protein of wheat called?
Why is flour containing much gluten preferred by bakers?
Can protein be formed without nitrogen?
If plants were allowed to complete their growth without a supply of this ingredient, what would be the result?
Thesecond classof proximates, though forming only a small part of the plant, are of the greatest importance to the farmer, being the ones from whichanimal muscle[H]is made. They consist, as will be recollected, of carbon, hydrogen, oxygen andnitrogen, or ofallof the organic elements of plants. They are all of much the same character, though each kind of plant has its peculiar form of this substance, which is known under the general name ofprotein.
The protein of wheat is calledgluten—that of Indian corn iszein—that of beans and peas islegumin. In other plants the protein substances arevegetable albumen,casein, etc.
Gluten absorbs large quantities of water, which causes it to swell to a great size, and become full of holes. Flour which contains much gluten, makes light, porous bread, and is preferred by bakers, because it absorbs so large an amount of water.
What is the result if a field be deficient in nitrogen?
What is the result if a field be deficient in nitrogen?
The protein substances are necessary to animal and vegetable life, and none of our cultivated plants will attain maturity (complete their growth), unless allowed the materials required for forming this constituent. To furnish this condition is the object of nitrogen given to plants as manure. If nonitrogenis supplied the protein substances cannot be formed, and the plant must cease to grow.
When on the contraryammoniais given to the soil (by rains or otherwise), it furnishes nitrogen, while the carbonic acid and water yield the other constituents of protein, and a healthy growth continues, provided that the soil contains themineralmatters required in the formation of the ash, in a condition to be useful.
The wisdom of this provision is evident when we recollect that the protein substances are necessary to the formation of muscle in animals, for if plants were allowed to complete their growth without a supply of this ingredient, our grain and hay might not be sufficiently well supplied with it to keep our oxen and horses in working condition, while under the existing law plants must be of nearly a uniform quality (in this respect), and if a field is short of nitrogen, its crop will not be large, and of a very poor quality, but the soil will produce good plants as long as the nitrogen lasts, and then the growth must cease.[I]
That this principle may be clearly understood, it may be well to explain more fully the application ofthe proximate constituents of plants in feeding animals.
Of what are the bodies of animals composed?What is the office of vegetation?What part of the animal is formed from the first class of proximates?From the second?Which contains the largest portions of inorganic matter, plants or animals?Must animals have a variety of food, and why?
Of what are the bodies of animals composed?
What is the office of vegetation?
What part of the animal is formed from the first class of proximates?
From the second?
Which contains the largest portions of inorganic matter, plants or animals?
Must animals have a variety of food, and why?
Animals are composed (like plants) of organic and inorganic matter, and every thing necessary to build them up exists in plants. It seems to be the office of the vegetable world to prepare the gases in the atmosphere, and the minerals in the earth for the uses of animal life, and to effect this plants put these gases and minerals together in the form of the variousproximates(or compound substances) which we have just described.
In animals the compounds containingno nitrogencomprise the fatty substances, parts of the blood, etc., while the protein compound, or those whichdo contain nitrogen, form the muscle, a part of the bones, the hair, and other portions of the animal.
Animals contain a larger proportion of inorganic matter than plants do. Bones contain a large quantity of phosphate of lime, and we find other inorganic materials performing important offices in the system.
In order that animals may be perfectly developed, they must of course receive as food all of the materials required to form their bodies. They cannot live if fed entirely on one ingredient. Thus, ifstarchalonebe eaten by the animal, he might becomefat, but his strength would soon fail, because his food contains nothing to keep up the vigor of hismuscles. If on the contrary the food of an animal consisted entirely ofgluten, he might be very strong from a superior development of muscle, but would not be fat. Hence we see that in order to keep up the proper proportion of both fat and muscle in our animals (or in ourselves), the food must be such as contains a proper proportion of the two kinds of proximates.
Why is grain good for food?On what does the value of flour depend?Is there any relation between the ashy part of plants and those of animals?How may we account for unhealthy bones and teeth?
Why is grain good for food?
On what does the value of flour depend?
Is there any relation between the ashy part of plants and those of animals?
How may we account for unhealthy bones and teeth?
It is for this reason that grain, such as wheat for instance, is so good for food. It contains both classes of proximates, and furnishes material for the formation of both fat and muscle. The value offlourdepends very much on the manner in which it is manufactured. This will be soon explained.
What is a probable cause of consumption?What is an important use of the first class of proximates?What may lungs be called?Explain the production of heat during decomposition.Why is the heat produced by decay not perceptible?
What is a probable cause of consumption?
What is an important use of the first class of proximates?
What may lungs be called?
Explain the production of heat during decomposition.
Why is the heat produced by decay not perceptible?
Apart from the relations between theproximate principlesof plants, and those of animals, there exists an important relation between theirashyorinorganicparts; and, food in order to satisfy the demands of animal life, must contain the mineral matter required for the purposes of that life. Take bones for instance. If phosphate of lime is not always supplied in sufficient quantities by food, animals are prevented from the formation of healthy bones. This is particularlyto be noticed in teeth. Where food is deficient of phosphate of lime, we see poor teeth as a result. Some physicians have supposed that one of the causes of consumption is the deficiency of phosphate of lime in food.
Why is the heat produced by combustion apparent?Explain the production of heat in the lungs of animals?Why does exercise augment the animal heat?Under what circumstances is the animal's own fat used in the production of heat?
Why is the heat produced by combustion apparent?
Explain the production of heat in the lungs of animals?
Why does exercise augment the animal heat?
Under what circumstances is the animal's own fat used in the production of heat?
The first class of proximates (starch, sugar, gum, etc.), perform an important office in the animal economy aside from their use in making fat. They constitute thefuelwhich supplies the animal's fire, and gives him hisheat. The lungs of men and other animals may be called delicatestoves, which supply the whole body with heat. But let us explain this matter more fully. If wood, starch, gum, or sugar, be burned in a stove, they produce heat. These substances consist, as will be recollected, of carbon, hydrogen, and oxygen, and when they are destroyed in any way (provided they be exposed to the atmosphere), the hydrogen and oxygen unite and form water, and the carbon unites with the oxygen of the air and forms carbonic acid, as was explained in a preceding chapter. This process is always accompanied by the liberation ofheat, and theintensityof this heat depends on thetimeoccupied in itsproduction. In the case of decay, the chemical changes take place so slowly that the heat, being conducted away as soonas formed, is not perceptible to our senses. In combustion (or burning) the same changes take place with much greater rapidity, and the sameamountof heat being concentrated, or brought out in a far shorter time, it becomes intense, and therefore apparent. In the lungs of animals the same law holds true. The blood contains matters belonging to this carbonaceous class, and they undergo in the lungs the changes which have been described under the head of combustion and decay. Their hydrogen and oxygen unite, and form the moisture of the breath, while their carbon is combined with the oxygen of the air drawn into the lungs, and is thrown out as carbonic acid. The same consequence—heat—results in this, as in the other cases, and this heat is produced with sufficient rapidity for the animal necessities. When an animal exercises violently, his blood circulates with increased rapidity, thus carrying carbon more rapidly to the lungs. The breath also becomes quicker, thus supplying increased quantities of oxygen. In this way the decomposition becomes more rapid, and the animal is heated in proportion.
Thus we see that food has another function besides that of forming animal matter, namely to supply heat. When the food does not contain a sufficient quantity of starch, sugar, etc., to answerthe demands of the system theanimal's own fatis carried to the lungs, and there used in the production of heat. This important fact will be referred to again.
FOOTNOTES:[G]Byproximate principle, we mean that combination of vegetable elements which is known as a vegetable product, such aswood, etc.[H]Muscleislean meat, it gives to animals their strength and ability to perform labor.[I]This, of course, supposes that the soil is fertile in other respects.
[G]Byproximate principle, we mean that combination of vegetable elements which is known as a vegetable product, such aswood, etc.
[G]Byproximate principle, we mean that combination of vegetable elements which is known as a vegetable product, such aswood, etc.
[H]Muscleislean meat, it gives to animals their strength and ability to perform labor.
[H]Muscleislean meat, it gives to animals their strength and ability to perform labor.
[I]This, of course, supposes that the soil is fertile in other respects.
[I]This, of course, supposes that the soil is fertile in other respects.
Of what proximate are plants chiefly composed?What is the principal constituent of the potato root?Of the carrot and turnip?What part of the plant contains usually the most nutriment?
Of what proximate are plants chiefly composed?
What is the principal constituent of the potato root?
Of the carrot and turnip?
What part of the plant contains usually the most nutriment?
Let us now examine plants with a view to learning thelocationof the various plants.
The stem or trunk of the plant or tree consists almost entirely ofwoody fibre; this also forms a large portion of the other parts except the seeds, and, in some instances, the roots. The roots of the potato contain large quantities ofstarch. Other roots such as thecarrotandturnipcontainpectic acid,[J]a nutritious substance resembling starch.
It is in theseedhowever that the more nutritive portions of most plants exist, and here they maintaincertain relative positions which it is well to understand, and which can be best explained by reference to the following figures, as described by Prof. Johnston:—
Fig. 1.Fig. 1.
"Thusashows the position of the oil in the outer part of the seed—it exists in minute drops, inclosed in six-sided cells, which consists chiefly of gluten;b, the position and comparative quantity of the starch, which in the heart of the seed is mixed with only a small proportion of gluten;c, the germ or chit which contains much gluten."[K]
Is the composition of the inorganic matter of different parts of the plant the same, or different?What is the difference between the ash of the straw and that of the grain of wheat?
Is the composition of the inorganic matter of different parts of the plant the same, or different?
What is the difference between the ash of the straw and that of the grain of wheat?
The location of theinorganicpart of plants is one of much interest, and shows the adaptation of each part to its particular use. Take a wheat plant, for instance—the stalk, the leaf, and the grain, show in their ashes, important difference of composition. The stalk or straw contains three or four times as large a proportion of ash as the grain, and a no less remarkable difference of composition may be noticedin the ashes of the two parts. In that of the straw, we find a large proportion of silica and scarcely any phosphoric acid, while in that of the grain there is scarcely a trace of silica, although phosphoric acid constitutes more than one half of the entire weight. The leaves contain a considerable quantity of lime.
What is the reason for this difference?In what part of the grain does phosphoric acid exist most largely?
What is the reason for this difference?
In what part of the grain does phosphoric acid exist most largely?
This may at first seem an unimportant matter, but on examination we shall see the use of it. The straw is intended to support the grain and leaves, and to convey the sap from the roots to the upper portions of the plant. To perform these offices,strengthis required, and this is given by thesilica, and the woody fibre which forms so large a proportion of the stalk. The silica is combined with an alkali, and constitutes the glassy coating of the straw. While the plant is young, this coating is hardly apparent, but as it grows older, as the grain becomes heavier, (verging towards ripeness), the silicious coating of the stalk assumes a more prominent character, and gives to the straw sufficient strength to support the golden head. The straw is not the most important part of the plant asfood, and therefore requires but little phosphoric acid.
Why is Graham flour more wholesome than fine flour?Are the ashes of all plants the same in their composition?
Why is Graham flour more wholesome than fine flour?
Are the ashes of all plants the same in their composition?
The grain, on the contrary, is especially intended as food, and therefore must contain a large proportion of phosphoric acid—this being, as we have already learned, necessary to the formation of bone—while, as it has no necessity for strength, and as silica is not needed by animals, this ingredient exists in the grain only in a very small proportion. It may be well to observe that the phosphoric acid of grain exists most largely in the hard portions near the shell, or bran. This is one of the reasons why Graham flour is more wholesome than fine flour. It contains all of the nutritive materials which render the grain valuable as food, while flour which is very finely bolted[L]contains only a small part of the outer portions of the grain (where the phosphoric acid, protein and fatty matters exist most largely). The starchy matter in the interior of the grain, which is the least capable of giving strength to the animal, is carefully separated, and used as food for man, while the better portions, not being ground so finely, are rejected. This one thing alone may be sufficient to account for the fact, that the lives of men have become shorter and less blessed with health and strength, than they were in the good old days when a stone mortar and a coarse sieve made a respectable flour mill.
Another important fact concerning the ashes of plants is the difference of their composition in different plants. Thus, the most prominent ingredient inthe ash of the potato ispotash; of wheat and other grains,phosphoric acid; of meadow hay,silica; of clover,lime; of beans,potash, etc. In grain,potash(orsoda), etc., are among the important ingredients.