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?
The second class of proximates, though forming only a small part of the plant, are of the greatest importance to the farmer, being the ones from which animal muscle8 is made. They consist, as will be recollected, of carbon, hydrogen, oxygen and nitrogen, or of all of 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 of protein.
The protein of wheat is called gluten—that of Indian corn is zein—that of beans and peas is legumin. In other plants the protein substances are vegetable 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?
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 no nitrogen is supplied the protein substances cannot be formed, and the plant must cease to grow.
When on the contrary ammonia is 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 the mineral matters 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.9
That this principle may be clearly understood, it may be well to explain more fully the application of the 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?
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 various proximates (or compound substances) which we have just described.
In animals the compounds containing no nitrogen comprise the fatty substances, parts of the blood, etc., while the protein compound, or those which do 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, if starch alone be eaten by the animal, he might become fat, but his strength would soon fail, because his food contains nothing to keep up the vigor of his muscles. If on the contrary the food of an animal consisted entirely of gluten, 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?
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 of flour depends 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?
Apart from the relations between the proximate principles of plants, and those of animals, there exists an important relation between their ashy or inorganic parts; 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 particularly to 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?
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 the fuel which supplies the animal's fire, and gives him his heat. The lungs of men and other animals may be called delicate stoves, 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 of heat, and the intensity of this heat depends on the time occupied in its production. In the case of decay, the chemical changes take place so slowly that the heat, being conducted away as soon as formed, is not perceptible to our senses. In combustion (or burning) the same changes take place with much greater rapidity, and the same amount of 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