MikhailT/lj-speech huggingface dataset:
and it is probable that amyloid substances are universally present in the animal organism, though not in the precise form of starch.
Moreover, although it remains true that there is an inverse relation between the green plant in sunshine and the animal,
in so far as under these circumstances the green plant
decomposes carbonic acid and exhales oxygen while the animal absorbs oxygen and exhales carbonic acid,
yet the exact researches of the modern chemical investigators of the physiological processes of plants have clearly demonstrated the fallacy
of attempting to draw any general distinction between animals and vegetables on this ground. In fact, the difference vanishes with the sunshine,
even in the case of the green plant, which in the dark absorbs oxygen and gives out carbonic acid like any animal.
On the other hand, those plants, such as the fungi,
which contain no chlorophyll and are not green, are always, so far as respiration is concerned, in the exact position of animals.
They absorb oxygen and give out carbonic acid.
Thus, by the progress of knowledge, Cuvier's fourth distinction between the animal and the plant
has been as completely invalidated as the third and second, and even the first can be retained only in a modified form
and subject to exceptions.
But has the advance of biology simply tended to break down old distinctions without establishing new ones?
With a qualification, to be considered presently, the answer to this question is undoubtedly in the affirmative.
The famous researches of Schwann and Schleiden in 1837 and the following years
founded the modern science of histology or that branch of anatomy which deals with the ultimate visible structure of organisms as revealed by the microscope,
and from that day to this the rapid improvement of methods of investigation and the energy of a host of accurate observers
have given greater and greater breadth and firmness to Schwann's great generalization
that a fundamental unity of structure obtains in animals and plants,
and that, however diverse may be the fabrics or tissues of which their bodies are composed, all these varied structures result
from the metamorphosis of morphological units (termed cells in a more general sense than that in which the word "cells" was at first employed),
which are not only similar in animals and in plants respectively,
but present a close resemblance when those of animals and those of plants are compared together.
The contractility which is the fundamental condition of locomotion," continues Huxley,
has not only been discovered to exist far more widely among plants than was formerly imagined,
but in the plants the act of contraction has been found to be accompanied,
as Dr. Burdon Sanderson's interesting investigations have shown, by a disturbance of the electrical state of the contractile substance
comparable to that which was found by Du Bois Reymond to be a concomitant of the activity of ordinary muscle in animals. Again,
I know of no test by which the reaction of the leaves of the Sundew and of other plants to stimuli, so fully and carefully studied by Mr. Darwin,
can be distinguished from those acts of contraction following upon stimuli, which are called "reflex" in animals.
On each lobe of the bi-lobed leaf of Venus flytrap are three delicate filaments which stand out at right angles from the surface of the leaf.
Touch one of them with the end of a fine human hair
and the lobes of the leaf instantly close together in virtue of an act of contraction of part of their substance,
just as the body of a snail contracts into its shell when one of its "horns" is irritated.
The reflex action of the snail is the result of the presence of a nervous system in the animal.
A molecular change takes place in the nerve of the tentacle,
is propagated to the muscles by which the body is retracted, and causing them to contract, the act of retraction is brought about.
Of course the similarity of the acts does not necessarily involve the conclusion that the mechanism by which they are effected is the same
but it suggests a suspicion of their identity which needs careful testing.
The results of inquiries into the structure of the nervous system of animals
converge toward the conclusion that the nerve fibers, which have been regarded as ultimate elements of nervous tissue,
are not such, but are simply the visible aggregations of vastly more attenuated filaments,
the diameter of which dwindles down to the limits of our present microscopic vision,
greatly as these have been extended by modern improvements of the microscope, and that a nerve is, in its essence,
nothing but a linear tract of specially modified protoplasm between two points of an organism
one of which is able to affect the other by means of the communication so established.
Hence it is conceivable that even the simplest living being may possess a nervous system.
And the question whether plants are provided with a nervous system or not thus acquires a new aspect and presents the histologist and physiologist
with a problem of extreme difficulty, which must be attacked from a new point of view and by the aid of methods which have yet to be invented.
"Thus it must be admitted," he says again, "that plants may be contractile and locomotive;
that, while locomotive, their movements may have as much appearance of spontaneity as those of the lowest animals,
and that many exhibit actions comparable to those which are brought about by the agency of a nervous system in animals.
And it must be allowed to be possible that further research may reveal the existence of something comparable to a nervous system in plants.
So that I know not where we can hope to find any absolute distinction between animals and plants, unless we return to their mode of nutrition
and inquire whether certain differences of a more occult character than those imagined to exist by Cuvier,
and which certainly hold good for the vast majority of animals and plants, are of universal application.
A bean may be supplied with water in which salts of ammonia and certain other mineral salts are dissolved in due proportion,
with atmospheric air containing its ordinary minute dose of carbonic acid and with nothing else but sunlight and heat.
Under these circumstances, unnatural as they are, with proper management, the bean will thrust forth its radicle and its plumule;
the former will grow down into roots, the latter grow up into the stem and leaves of a vigorous bean-plant,
and this plant will, in due time, flower and produce its crop of beans just as if it were grown in the garden or in the field.
The weight of the nitrogenous protein compounds,
of the oily, starchy, saccharine and woody substances contained in the full-grown plant and its seeds
will be vastly greater than the weight of the same substances contained in the bean from which it sprang.
But nothing has been supplied to the bean save water, carbonic acid, ammonia, potash, lime,
iron and the like in combination with phosphoric, sulphuric and other acids.
Neither protein, nor fat, nor starch, nor sugar, nor any substance in the slightest degree resembling them has formed part of the food of the bean.
But the weights of the carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur and other elementary bodies contained in the bean-plant
and in the seeds which it produces are exactly equivalent to the weights of the same elements which have disappeared from the materials supplied to the bean during its growth.
Whence it follows that the bean has taken in only the raw materials of its fabric and has manufactured them into bean-stuffs.
The bean has been able to perform this great chemical feat by the help of its green coloring matter, or chlorophyll,
for it is only the green parts of the plant which, under the influence of sunlight, have the marvelous power of decomposing carbonic acid,
setting free the oxygen and laying hold of the carbon which it contains.
In fact, the bean obtains two of the absolutely indispensable elements of its substance from two distinct sources.
The watery solution, in which its roots are plunged, contains nitrogen but no carbon;
the air, to which the leaves are exposed, contains carbon,
but its nitrogen is in the state of a free gas, in which condition the bean can make no use of it,
and the chlorophyll is the apparatus by which the carbon is extracted from the atmospheric carbonic acid, the leaves being the chief laboratories
The Science: History of the Universe, Volume 5. Edited by Francis Rolt-Wheeler. Biology. Chapter 8.
Life Processes. Part One.
Nutrition thus, as has been pointed out, makes it possible to classify most organisms as animals or plants.
Yet there are many unicellular forms in which both kinds of nutrition go on at the same time;
that is, the forms may possess a mouth for the ingestion of solid food and green coloring matter, chlorophyll,
for the manufacture of starchy food from gaseous matter.
Many of the lowest forms of life have long been puzzles
and the beginner in biological study is surprised to find them described in textbooks of both botany and zoology.
The fact is that they are on the border line, are neither plants nor animals but simply organisms.
Since they cannot be classified, it is necessary that they be listed both under botany and zoology, in order to make sure that they will not be omitted entirely.
Because of these uncertain forms of life,
Haeckel proposed once to include all one-celled animals and plants in a third kingdom to be called Protista (meaning the first of all life).
Parker's definition of animals and plants,
based on the foregoing considerations, is convenient for distinguishing between animals and plants in all cases except the doubtful unicellar forms.
He says: Animals are organisms of fixed and definite form, in which the cell-body is not covered with a cellulose wall.
They ingest solid proteinaceous food,
their nutritive processes result in oxidation, they have a definite organ of excretion and are capable of automatic movement
Plants are organisms of constantly varying form in which the cell body is surrounded by a cellulose wall;
they cannot ingest solid food, but are nourished by a watery solution of nutrient materials.
If chlorophyll is present, the carbon dioxide of the air serves as a source of carbon,
nitrogen is obtained from simple salts and the nutritive processes result in deoxidation;
if chlorophyll is absent, carbon is obtained from sugar or some similar compound,
nitrogen either from simple salts or from proteids, and the process of nutrition is one of oxidation.
There is no special excretory organ, and, except in the case of certain reproductive bodies, there is usually no locomotion.
The important point to recognize is that these boundaries are artificial and that there are no scientific frontiers in Nature.
As in the liquefaction of gases, there is a "critical point" at which the substance under experiment is neither gaseous nor liquid.
as in a mountainous country, it is impossible to say where mountain ends and valley begins; as in the development of an animal,
it is futile to argue about the exact period when, for instance, the egg becomes a tadpole or the tadpole a frog,
so in the case under discussion.
The distinction between the higher plants and animals is perfectly sharp and obvious,
but when the two groups are traced downward they are found gradually to merge,
as it were, into an assemblage of organisms which partake of the characters of both kingdoms and cannot without a certain violence
be either included in or excluded from either.
When any given "protist" has to be classified the case must be decided on its individual merits;
the organism must be compared in detail with all those which resemble it closely in structure, physiology and life history,
and then a balance must be struck and the doubtful form placed in the kingdom with which it has, on the whole, most points in common.
It will no doubt occur to the reader that, on the theory of evolution,
the fact of the animal and vegetable kingdoms being related to one another like two trees united at the roots may be accounted for by the hypothesis that
the earliest organisms were protists and that from them animals and plants were evolved along divergent lines of descent.
And in this connection the fact that some bacteria -- the simplest organisms known and devoid of chlorophyll
may flourish in solutions wholly devoid of organic matter is very significant.
The lower plants and animals referred to above are so far from everyday observation
and hence so unfamiliar that to most people the comparison made will mean little in terms of ordinary green flowering plants and common vertebrate animals.
In order to emphasize the fundamental similarity of organic function in higher and lower animals and plants, let us compare any higher plant
e.g., a bean plant with a higher animal, e.g., frog or even man.
In each the life is the sum total of a series of definite processes -- nutrition or food supply,
circulation, metabolism, excretion, oxygenation (part of respiration),
movement, irritability (nervous activity) and reproduction.
In turn these will be compared for the animal and the plant,
following in part the comparisons of certain animals and plants by Sedgwick and Wilson and others.
These comparisons will, however, be translated into terms applicable to any species of higher plants or animals.
In the nutrition of the animal the most essential and characteristic part of the food supply is derived from vegetable
or animal matter in the form of various organic compounds, of which the most important are proteids (protoplasm, albumen, etc.),
carbohydrates (starch, cellulose) and fats.
These materials are used by the animal in the manufacture of new protoplasm to take the place of that which has been used up.
It is, however, impossible for the animal to build these materials directly into the substance of its own body.
They must first undergo certain preparatory chemical changes known collectively as digestion
and only after the completion of this process can all the food be absorbed into the circulation.
For this purpose the food is taken not into the body proper, but into a kind of tubular chemical laboratory; called the alimentary canal,
through which it slowly passes, being subjected meanwhile to the action of certain chemical substances or reagents, known as digestive ferments.
These substances, which are dissolved in a watery liquid to form the digestive fluid, are secreted by the walls of the alimentary tube.
Through their action the solid portions are liquefied and the food is rendered capable of absorption into the body proper.
The food supply of the higher plant, like that of the animal, is the source of the required matter and energy,
but unlike that of the animal, it is not chiefly an income of foods, but only of the raw materials of food.
Matter enters the plant in the liquid or gaseous form by diffusion,
both from the soil through the roots (liquids) and from the atmosphere through the leaves (gases).
We have here the direct absorption into the body proper of food-stuffs precisely as the animal takes in water and oxygen.
Energy enters the plant, to a small extent,
as the potential energy of foodstuffs, but comes in principally as the kinetic energy of sunlight absorbed in the leaves.
Of the substances the solids (salts, etc.) must be dissolved in water before they can be taken in.
Water and dissolved salts continually pass by diffusion from the soil into the roots, where together they constitute the sap.
The sap travels throughout the whole plant, the main though not the only cause of movement
being the constant transpiration (evaporation) of watery vapor from the leaves, especially through the stomata.
The gaseous matters (carbon dioxide, oxygen, nitrogen) enter the plant mainly by diffusion from the atmosphere,
are dissolved by the sap in the leaves and elsewhere and thus may pass to every portion of the plant.
to the chlorophyll bodies or chromatophores, for plants which, like fungi, etc., are devoid of chlorophyll, are unable thus to acquire energy.
Entering the chlorophyll bodies, the kinetic energy of sunlight is applied to the decomposition of carbon dioxide and water.
After passing through manifold but imperfectly known processes, the elements of these substances finally reappear as starch,
often in the form of granules embedded in the chlorophyll bodies and free oxygen, most of which is returned to the atmosphere.
Thus the leaf of a green plant in the light is continually absorbing carbon dioxide and giving forth free oxygen.
Carbon dioxide and water contain no potential energy, since the affinities of their constituent elements are completely satisfied.
Starch, however, contains potential energy, since the molecule is relatively unstable
i.e., capable of decomposition into simpler, stabler molecules in which stronger affinities are satisfied.
And this is due to the fact that in the manufacture of starch in the chlorophyll bodies
the kinetic energy of sunlight was expended in lifting the atoms into position of vantage, thus endowing them with energy of position.
In this way some of the radiant and kinetic energy of the sun comes to be stored up as potential energy in the starch.
In short, the green plant is able by cooperation with sunlight to use simple raw materials (carbon dioxide, water, oxygen, etc.)
poor in energy or devoid of it, and out of them to manufacture food -- i.e. complex compounds rich in available potential energy.
This power is possessed by green plants alone; all other organisms being dependent for energy upon the potential energy of ready-made food.
This must, in the first instance, be provided for them by green plants, and hence without chlorophyll-bearing plants,
animals (and colorless plants as well) apparently could not long exist.
The plant absorbs also a small amount of kinetic energy, independently of the sunlight, in the form of heat.
This, however, is probably not a source of vital energy, but only contributes to the maintenance of the body temperature.
Food (starch) thus produced in the green leaves of higher plants and the inorganic foods
furnish the materials and energy required for the life and growth of the plant.
The circulatory system distributes these foods. In animals foods prepared for absorption in the stomach and intestine (by digestion)
are absorbed by the circulating liquids (blood and lymph) and transported to all cells of the animal body.
In the plant the inorganic matter in water from the soil are absorbed by the roots and carried up definite tubes in the woody part of the stem.
The causes of this ascent are not clear,
but root pressure due to osmosis, capillary action and evaporation from the leaves are factors.
Just as the solid food of animals must be digested in preparation for absorption,
so starch manufactured in the leaves must be digested (dissolved) before it can be transported.
This is done by diastase, an enzyme of plant cells.
The change is from starch to a sugar capable of diffusion.
Dissolved in water, the sugar is transported down delicate tubes, chiefly in the growing bark region of the stem.
It is clear that there are upward and downward currents of water containing food (comparable to blood of an animal),
but no system of complete circulation as in the blood vessels of a higher animal.
However, the result in distributed food is the same in the plant and in the animal.
In the cells the foods undergo metabolic changes.
In an animal the foods in the circulating liquids, blood and lymph, are selected and absorbed by the cells.
Only proteid foods form new protoplasm
and even of proteids only a limited amount, 75 to one hundred grams a day for a man, is built into new protoplasm.
The excess undergoes oxidation and forms nitrogen excretions.
The foods containing only the elements carbon, hydrogen and oxygen (fats and carbohydrates)
are directly oxidized to excretions and, lacking nitrogen, cannot serve for making new animal protoplasm.
Fat and carbohydrate foods, then, never become living matter.
They may be stored, especially as fat, until needed for oxidation to supply energy.
The building up of the protoplasm from proteids is anabolism, constructive metabolism.
The destruction of protoplasm, excess proteids or the fat and carbohydrate foods is catabolism, destructive metabolism.
which could be derived by the ordinary chemical evolution of protoplasm, proteid, sugar, starch or fats.
In the plant, starch, as has been seen, is first formed in the chlorophyll-bodies.
But the formation of starch, all important as it is, is after all only the manufacture of food
as a preliminary to the real processes of nutrition.
These processes must take place everywhere in ordinary protoplasm,
for it is here that oxidation occurs and the need for a renewal of matter and energy consequently arises.
Sooner or later the starch grains are changed into a kind of sugar (glucose), which, unlike starch, dissolves in the sap
and may thus be easily transported to all parts of the plant.
Wherever there is need for new protoplasm, whether to repair previous waste or to supply materials for growth,
after absorption into the cells the elements of the starch (or glucose) are, by the living protoplasm, in some unknown way
combined with nitrogen and sulphur (probably also with salts, water, etc.) to form proteid matter.
The particles of this newly formed compound are incorporated into the protoplasm.
If a larger quantity of starch is formed in the chlorophyll bodies than is immediately needed by the protoplasm for purposes of repair or growth,
it may be reconverted into starch after journeying as glucose through the plant
and be laid down as "reserve starch" in the cells of root or stem or elsewhere.
Apparently when this reserve supply is finally needed at any point in the plant, it is again changed to glucose and transported thither.
It is probable that new leaves and new tissues generally are always formed in part from this reserve starch.
In the plant as in the animal metabolism must consist of anabolic and catabolic processes.
The construction in the cells of new proteid from the absorbed carbohydrate and the materials from the soil is true anabolism.
It is also clear that catabolism or oxidation for the liberation of energy occurs as in animals, but this process is slower.
Probably foods containing carbon, hydrogen and oxygen are the sources of energy in the higher plants as in animals.
In both plants and animals simple waste substances result from the catabolic processes in the cells.
In the animal carbon dioxide, water and nitrogen compounds are the chief excretions.
They are absorbed by the circulating liquids and carried to the eliminating organs, lungs and kidneys chiefly, for elimination.
In the higher plants the excretions are carbon dioxide, which escapes through the epidermis of root, stem and leaf and through the stomata;
water which is lost by evaporation, especially from the leaf surface through the stomata;
excretions which are lost by osmosis through the roots and the accumulated but useless mineral substances which are eliminated by leaf fall.
In both animals and plants oxygen is essential to the catabolic part of metabolism.
Hence oxygen must be supplied to the cells.
Oxygenation is the term used to denote the oxygen-supplying part of respiration;
the other part of respiration, elimination of carbon dioxide, has been treated under excretions.
In the animal oxygen is absorbed by the blood, in excess by the hemoglobin of the red cells of the blood
and later is absorbed from the blood and lymph by all the living cells.
In the plant also oxygen is absorbed through the epidermis and stomata from the air.
This process is, however, obscured during the day because of the oxygen freed in the manufacture of starch which goes on at that time.
Probably this freed oxygen is used for the purpose of oxygenation, but more is freed in the photosynthetic process than is needed for oxygenation
and hence the excess oxygen is eliminated while starch manufacture is in process.
In comparing a higher animal and a green plant confusion must be avoided regarding the part played by oxygen and carbon dioxide in true respiration
with the part played by the same substances in starch formation (photosynthesis).