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A Book of Natural History.
The publishers' acknowledgments are due to Miss Margaret Warner Morley and Messrs. A. C. McClurg & Co. for permission to use "Life Growth,--Frogs"; to Mr. W. S. Blatchley and _The Popular Science Monthly_ for "How Animals Spend the Winter" and "Two Fops Among the Fishes"; to Messrs. Houghton, Mifflin & Co. for "Birds' Nests," by John Burroughs; to Mr. L. Bruner and the Nebraska Ornithologists'
Union for "Birds in Their Relation to Agriculture"; to G. W. and E. G.
Peckham for "A Wasp and Its Prey" and "Protective Resemblances in Spiders"; to President David Starr Jordan and _The Popular Science Monthly_ for "Old Rattler and the King Snake"; to President Jordan and A. C. McClurg & Co. for "The Story of a Strange Land."
ANIMALS, BIRDS, AND FISHES
DAVID STARR JORDAN, LL.D.
This volume is made up from the writings of naturalists who have told us of the behavior of animals as they have seen it at first hand and of the beginnings and the growth of life so far as they know about it.
In selecting these from the wealth of available material the editor has been guided by this rule: The subject matter must be interesting to young people; it must be told in a clear and attractive style; and most important of all, it must deal with actualities. We have seen in the last few years a marked revival of nature studies. This has led to a wider range of interest in natural phenomena and in the growth and ways of animals and plants. If this movement is not to be merely a pa.s.sing fad, the element of truthfulness must be constantly insisted upon. If a clever imagination, or worse, sentimental symbolism, be subst.i.tuted for the truth of nature, the value of such studies is altogether lost.
The essence of character-building lies in action. The chief value of nature study in character-building is that, like life itself, it deals with realities. One must in life make his own observations, frame his own inductions, and apply them in action as he goes along.
The habit of finding out the best thing to do next and then doing it is the basis of character. Nature-study, if it be genuine, is essentially doing. To deal with truth is necessary, if we are to know truth when we see it in action. The rocks and sh.e.l.ls, the frogs and lilies, always tell the absolute truth. Every leaf on the tree is an original doc.u.ment in botany. When a thousand are used or used up, the archives of Nature are just as full as ever. By the study of realities wisdom is built up. In the relations of objects he can touch and move, the child finds the limitations of his powers, the laws that govern phenomena, which his own actions must obey. So long as he deals with realities, these laws stand in their proper relation. "So simple, so natural, so true," says Aga.s.siz. "This is the charm of dealing with nature herself. She brings us back to absolute truth so often as we wander."
So long as a child is led from one reality to another, never lost in words or abstractions,--so long this natural relation remains. "What can I do with it?" is the beginning of wisdom. "What is it to me?" is the beginning of personal virtue.
By adding near things to near, the child grows in Knowledge.
Knowledge, tested and set in order, is Science. Nature-study is the beginning of science. It is the science of the child. The "world as it is" is the province of science. In proportion as our actions conform to the conditions of the world as it is, do we find the world beautiful, glorious, divine. The truth of the world as it is must be the final inspiration of art, poetry, and religion. The world, as men have agreed to say that it is, is quite another matter. The less our children hear of this, the less they may have to unlearn. Nature studies have long been valued as "a means of grace," because they arouse the enthusiasm, the love of work, which belongs to open-eyed youth. The child blase with moral precepts and irregular conjugations turns with fresh delight to the unrolling of ferns or the song of birds.
Nature must be questioned in earnest, or she will not reply. But to every serious question she will return a serious answer. "Simple, natural, and true," she tends to create simplicity and truth. Truth and virtue are but opposite sides of the same shield. As leaves pa.s.s over into flowers, and flowers into fruit, so are wisdom, virtue, and happiness inseparably related.
This little volume is a contribution to the subject matter of Nature Study. It is the work of students of nature, and their work is "simple, natural, and true," in so far as it is represented here.
[Ill.u.s.tration: (Signature) David Starr Jordan]
LELAND STANFORD JR. UNIVERSITY, CALIFORNIA, _April_ 22, 1902.
A BOOK OF NATURAL HISTORY
THE WONDER OF LIFE
(FROM HIS SCIENCE PRIMER, INTRODUCTION.)
BY PROFESSOR, T. H. HUXLEY.
Every one has seen a cornfield. If you pluck up one of the innumerable wheat plants which are fixed in the soil of the field, about harvest time, you will find that it consists of a stem which ends in a root at one end and an ear at the other, and that blades or leaves are attached to the sides of the stem. The ear contains a mult.i.tude of oval grains which are the seeds of the wheat plant. You know that when these seeds are cleared from the husk or bran in which they are enveloped, they are ground into fine powder in mills, and that this powder is the flour of which bread is made. If a handful of flour mixed with a little cold water is tied up in a coa.r.s.e cloth bag, and the bag is then put into a large vessel of water and well kneaded with the hands, it will become pasty, while the water will become white. If this water is poured away into another vessel, and the kneading process continued with some fresh water, the same thing will happen.
But if the operation is repeated the paste will become more and more sticky, while the water will be rendered less and less white, and at last will remain colorless. The sticky substance which is thus obtained by itself is called gluten; in commerce it is the substance known as maccaroni.
If the water in which the flour has thus been washed is allowed to stand for a few hours, a white sediment will be found at the bottom of the vessel, while the fluid above will be clear and may be poured off.
This white sediment consists of minute grains of starch, each of which, examined with the microscope, will be found to have a concentrically laminated structure. If the fluid from which the starch was deposited is now boiled it will become turbid, just as white of egg diluted with water does when it is boiled, and eventually a whitish lumpy substance will collect at the bottom of the vessel. This substance is called vegetable alb.u.min.
Besides the alb.u.min, the gluten, and the starch, other substances about which this rough method of a.n.a.lysis gives us no information, are contained in the wheat grain. For example, there is woody matter or cellulose, and a certain quant.i.ty of sugar and fat. It would be possible to obtain a substance similar to alb.u.min, starch, saccharine, and fatty matters, and cellulose, by treating the stem, leaves, and root in a similar fashion, but the cellulose would be in far larger proportion. Straw, in fact, which consists of the dry stem and leaves of the wheat plant, is almost wholly made up of cellulose. Besides this, however, it contains a certain proportion of mineral bodies, among them, pure flint or silica; and, if you should ever see a wheat rick burnt, you will find more or less of this silica, in a gla.s.sy condition, in the embers. In the living plant, all these bodies are combined with a large proportion of water, or are dissolved, or suspended in that fluid. The relative quant.i.ty of water is much greater in the stem and leaves than in the seed.
Everybody has seen a common fowl. It is an active creature which runs about and sometimes flies. It has a body covered with feathers, provided with two wings and two legs, and ending at one end in a neck terminated by a head with a beak, between the two parts of which the mouth is placed. The hen lays eggs, each of which is inclosed in a hard sh.e.l.l. If you break an egg the contents flow out and are seen to consist of the colorless glairy "white" and the yellow "yolk." If the white is collected by itself in water and then heated it becomes turbid, forming a white solid, very similar to the vegetable alb.u.min, which is called animal alb.u.min.
If the yolk is beaten up with water, no starch nor cellulose is obtained from it, but there will be plenty of fatty and some saccharine matter, besides substances more or less similar to alb.u.min and gluten.
The feathers of the fowl are chiefly composed of horn; if they are stripped off and the body is boiled for a long time, the water will be found to contain a quant.i.ty of gelatin, which sets into a jelly as it cools; and the body will fall to pieces, the bones and the flesh separating from one another. The bones consist almost entirely of a substance which yields gelatin when it is boiled in water, impregnated with a large quant.i.ty of salts of lime, just as the wood of the wheat stem is impregnated with silica. The flesh, on the other hand, will contain alb.u.min, and some other substances which are very similar to alb.u.min, termed fibrin and syntonin.
In the living bird, all these bodies are united with a great quant.i.ty of water, or dissolved, or suspended in water; and it must be remembered that there are sundry other const.i.tuents of the fowl's body and of the egg, which are left unmentioned, as of no present importance.
The wheat plant contains neither horn, nor gelatin, and the fowl contains neither starch, nor cellulose; but the alb.u.min of the plant is very similar to that of the animal, and the fibrin and syntonin of the animal are bodies closely allied to both alb.u.min and gluten.
That there is a close likeness between all these bodies is obvious from the fact that when any of them is strongly heated, or allowed to putrefy, it gives off the same sort of disagreeable smell; and careful chemical a.n.a.lysis has shown that they are, in fact, all composed of the elements carbon, hydrogen, oxygen, and nitrogen, combined in very nearly the same proportions. Indeed, charcoal, which is impure carbon, might be obtained by strongly heating either a handful of corn, or a piece of fowl's flesh, in a vessel from which the air is excluded so as to keep the corn or the flesh from burning. And if the vessel were a still, so that the products of this destructive distillation, as it is called, could be condensed and collected, we should find water and ammonia, in some shape or other, in the receiver. Now ammonia is a compound of the elementary bodies, nitrogen and hydrogen; therefore both nitrogen and hydrogen must have been contained in the bodies from which it is derived.
It is certain, then, that very similar nitrogenous compounds form a very large part of the bodies of both the wheat plant and the fowl, and these bodies are called proteids.
It is a very remarkable fact that not only are such substances as alb.u.min, gluten, fibrin, and syntonin, known exclusively as products of animal and vegetable bodies, but that every animal and every plant, at all periods of its existence, contains one or other of them, though, in other respects, the composition of living bodies may vary indefinitely. Thus, some plants contain neither starch nor cellulose, while these substances are found in some animals; while many animals contain no h.o.r.n.y matter and no gelatin-yielding substance. So that the matter which appears to be the essential foundation of both the animal and the plant is the proteid united with water; though it is probable that, in all animals and plants, these are a.s.sociated with more or less fatty and amyloid (or starchy and saccharine) substances, and with very small quant.i.ties of certain mineral bodies, of which the most important appear to be phosphorus, iron, lime, and potash.
Thus there is a substance composed of water + proteids + fat + amyloids + mineral matters which is found in all animals and plants; and, when these are alive, this substance is termed protoplasm.
The wheat plant in the field is said to be a living thing; the fowl running about the farmyard is also said to be a living thing. If the plant is plucked up, and if the fowl is knocked on the head, they soon die and become dead things. Both the fowl and the wheat plant, as we have seen, are composed of the same elements as those which enter into the composition of mineral matter, though united into compounds which do not exist in the mineral world. Why, then, do we distinguish this matter when it takes the shape of a wheat plant or a fowl, as living matter?
In the spring a wheat-field is covered with small green plants. These grow taller and taller until they attain many times the size which they had when they first appeared; and they produce the heads of flowers which eventually change into ears of corn.
In so far as this is a process of growth, accompanied by the a.s.sumption of a definite form, it might be compared with the growth of a crystal of salt in brine: but, on closer examination, it turns out to be something very different. For the crystal of salt grows by taking to itself the salt contained in the brine, which is added to its exterior; whereas the plant grows by addition to its interior: and there is not a trace of the characteristic compounds of the plant's body, alb.u.min, gluten, starch, or cellulose, or fat, in the soil, or in the water, or in the air.
Yet the plant creates nothing; and, therefore, the matter of the proteins and amyloids and fats which it contains must be supplied to it, and simply manufactured, or combined in new fashions, in the body of the plant.
It is easy to see, in a general way, what the raw materials are which the plant works up, for the plant get nothing but the materials supplied to it by the atmosphere and by the soil. The atmosphere contains oxygen and nitrogen, a little carbonic acid gas, a minute quant.i.ty of ammoniacal salts, and a variable proportion of water. The soil contains clay and sand (silica), lime, iron, potash, phosphorus, sulphur, ammoniacal salts, and other matters which are of no importance. Thus, between them, the soil and the atmosphere contain all the elementary bodies which we find in the plant; but the plant has to separate them and join them together afresh.
Moreover, the new matter, by the addition of which the plant grows, is not applied to its outer surface, but is manufactured in its interior; and the new molecules are diffused among the old ones.
The grain of wheat is a part of the flower of the wheat plant, which, when it becomes ripe, is easily separated. It contains a minute and rudimentary plant; and, when it is sown, this gradually grows, or becomes developed into, the perfect plant, with its stem, roots, leaves, and flowers, which again give rise to similar seeds. No mineral body runs through a regular series of changes of form and size, and then gives off parts of its substance which take the same course. Mineral bodies present no such development, and give off no seeds or germs. They do not reproduce their kind.
The fowl in the farmyard is incessantly pecking about and swallowing now a grain of corn, and now a fly or a worm. In fact, it is feeding, and, as every one knows, would soon die if not supplied with food. It is also a matter of every-day knowledge that it would not be of much use to give a fowl the soil of a cornfield, with plenty of air and water, to eat.
In this respect, the fowl is like all other animals; it cannot manufacture the proteid materials of its body, but it has to take them ready made, or in a condition which requires but very slight modification by devouring the bodies either of other animals or of plants. The animal or vegetable substances devoured are taken into the animal's stomach; they are there digested or dissolved; and thus they are fitted to be distributed to all parts of the fowl's own body, and applied to its maintenance and growth.
The fowl's egg is formed in the body of the hen, and is, in fact, part of her body inclosed in a sh.e.l.l and detached. It contains a minute rudiment of a fowl; and when it is kept at a proper temperature by the hen's sitting upon it, or otherwise for three weeks, this rudiment grows, or develops, at the expense of the materials contained in the yolk and the white, into a small bird, the chick, which is then hatched and grows into a fowl. The animal, therefore, is produced by the development of a germ in the same way as the plant; and, in this respect, all plants and all animals agree with one another, and differ from all mineral matter.