Adapted from Volume Four of The Natural History of Animals: The Animal Life of the World in Its Various Aspects and Relations by James Richard Ainsworth Davis (1903)

The examples of protective resemblance so far quoted are mostly permanent adaptations to one particular sort of surrounding. There are, however, numerous animals which possess the power of adjusting their color more or less rapidly so as to harmonize with a changing environment.

Some of the best known of these cases are found among those mammals and birds that inhabit countries more or less covered with snow during a part of the year. A good instance is afforded by the Irish or variable hare, which is chiefly found in Ireland and Scotland. In summer, this looks very much like an ordinary hare, though rather grayer in tint and smaller in size, but in winter it becomes white with the exception of the black tips to the ears. Investigations that have been made on the closely allied American hare seem to show that the phenomenon is due to the growth of new hairs of white hue. 

The common stoat is subject to similar color change in the northern parts of its range. In summer it is of a bright reddish brown color with the exception of the under parts, which are yellowish white, and the end of the tail, which is black. But in winter, the entire coat, save only the tip of the tail, becomes white, and in that condition the animal is known as an ermine. A similar example is afforded by the weasel. The seasonal change in the vegetarian Irish hare is purely of protective character, but in such an actively carnivorous creature as a stoat or weasel, it is aggressive as well, rendering the animal inconspicuous to its prey.

The phrase “harmonize with,” underlined in the first paragraph, most closely means __________.

Adapted from “Humming-Birds: As Illustrating the Luxuriance of Tropical Nature” in Tropical Nature, and Other Essays by Alfred Russel Wallace (1878)

The food of hummingbirds has been a matter of much controversy. All the early writers down to Buffon believed that they lived solely on the nectar of flowers, but since that time, every close observer of their habits maintains that they feed largely, and in some cases wholly, on insects. Azara observed them on the La Plata in winter taking insects out of the webs of spiders at a time and place where there were no flowers. Bullock, in Mexico, declares that he saw them catch small butterflies, and that he found many kinds of insects in their stomachs. Waterton made a similar statement. Hundreds and perhaps thousands of specimens have since been dissected by collecting naturalists, and in almost every instance their stomachs have been found full of insects, sometimes, but not generally, mixed with a proportion of honey. Many of them in fact may be seen catching gnats and other small insects just like fly-catchers, sitting on a dead twig over water, darting off for a time in the air, and then returning to the twig. Others come out just at dusk, and remain on the wing, now stationary, now darting about with the greatest rapidity, imitating in a limited space the evolutions of the goatsuckers, and evidently for the same end and purpose. Mr. Gosse also remarks, ” All the hummingbirds have more or less the habit, when in flight, of pausing in the air and throwing the body and tail into rapid and odd contortions. This is most observable in the Polytmus, from the effect that such motions have on the long feathers of the tail. That the object of these quick turns is the capture of insects, I am sure, having watched one thus engaged pretty close to me.”

What can we infer from the author’s use of the underlined phrase, “sometimes, but not generally”?

Adapted from “Humming-Birds: As Illustrating the Luxuriance of Tropical Nature” in Tropical Nature, and Other Essays by Alfred Russel Wallace (1878)

The food of hummingbirds has been a matter of much controversy. All the early writers down to Buffon believed that they lived solely on the nectar of flowers, but since that time, every close observer of their habits maintains that they feed largely, and in some cases wholly, on insects. Azara observed them on the La Plata in winter taking insects out of the webs of spiders at a time and place where there were no flowers. Bullock, in Mexico, declares that he saw them catch small butterflies, and that he found many kinds of insects in their stomachs. Waterton made a similar statement. Hundreds and perhaps thousands of specimens have since been dissected by collecting naturalists, and in almost every instance their stomachs have been found full of insects, sometimes, but not generally, mixed with a proportion of honey. Many of them in fact may be seen catching gnats and other small insects just like fly-catchers, sitting on a dead twig over water, darting off for a time in the air, and then returning to the twig. Others come out just at dusk, and remain on the wing, now stationary, now darting about with the greatest rapidity, imitating in a limited space the evolutions of the goatsuckers, and evidently for the same end and purpose. Mr. Gosse also remarks, ” All the hummingbirds have more or less the habit, when in flight, of pausing in the air and throwing the body and tail into rapid and odd contortions. This is most observable in the Polytmus, from the effect that such motions have on the long feathers of the tail. That the object of these quick turns is the capture of insects, I am sure, having watched one thus engaged pretty close to me.”

The meaning of the underlined phrase “on the wing” is __________.

"Cacti" by Ami Dave (2013)

Cacti are plants suited to the desert and we must keep this factor in mind always when growing ornamental cacti in our gardens, for it helps in the survival of the plant. For example, a cactus should never be watered over its body as it will start to rot. This is because it is covered with a waxy coating which prevents water loss through evaporation. When one waters the cactus over its body, the waxy coating is washed away and the plant begins to rot. The amount of water that you must supply to the cactus is very much dependent upon the season and upon the climate of the place. During the summer season one should water cacti every four days whereas in the rainy season once every fifteen days is quite enough.

Cacti need a minimum of two and a half hours of sunlight per day. However they should not be kept all day in the sun because they may wrinkle in too much of bright sunlight. Unlike other plants cacti produce carbon dioxide during the day and oxygen during the night. Hence, they are ideal plants to be kept in bedrooms to freshen up the air at night.

If the cactus plant is to thrive and prosper, the size of the pot in which it is grown has to be carefully monitored. The pot should always be a little smaller than the plant itself because it is only when the plant has to struggle to survive that it will thrive. If the pot is too spacious the struggle element is removed and the chances are that the cactus will die. Cacti are like human beings. When they suffer they will grow. Similarly if a cactus shows no signs of growth, stop the watering. It should be resumed only when the plant resumes growth.

The substrata of a cactus pot is ideally composed of pieces of broken bricks at the bottom, charcoal above it, then coarse sand and pebbles above it. Leaf mould is the best manure.

Grafting of cacti is very simple. A very small piece of the cactus plant should be stuck with cellotape to the plant that needs grafting. The smaller the piece the easier it is to graft. To reproduce cacti, one has to simply cut off a piece of the cactus, allow it to dry for a few days and then just place it over the cacti substrate. It will automatically develop roots.

To differentiate between cacti and other plants that look like cacti is very easy. All cacti have fine hair at the base of each thorn. The so-called thorns are in fact highly modified leaves which prevent loss of water through transpiration. If one ever gets pricked by cacti thorns, one should take cellotape, place it over the area where the thorns have penetrated the skin and then peel it off. All the thorns will get stuck to the cellotape and will be removed.

If the author were to add the underlined sentences, "Cacti are like human beings. When they suffer they will grow," to the third paragraph, what would these lines mean in context?

"Abstraction in the Sciences" by Matthew Minerd (2014)

Thinking “abstractly” is not a term that means quite the same thing in all of the sciences. Although we rarely think about this, it plays a key role in almost all of our day-to-day thought. Consider a zoologist working in a lab with many animals. When she is studying any individual tiger, she is not completely worried about the particular tiger—at least not primarily. Instead, she is trying to figure out certain characteristics of tigers in general. By meticulous testing, the zoologist carefully works out the physiology of tigers and considers what are absolutely necessary elements of their physical makeup. Even when she places a tiger in different habitats, her sight is aimed at the general condition of tigers and their needs in general.

However, things become even stranger when you start to consider how we think about mathematical objects. Consider the case of geometric figures. A triangle appears to be rather simple for most of us to think about. You can draw a triangle on a piece of paper, each side having a certain thickness and length. However when you think about this in geometry class, the triangle’s edges have no real thickness. Neither a point nor a line has a thickness for the mathematician. Such a thickness only exists on our paper, which represents the point or line. Consider also a line drawn on a piece of graph paper. Technically, there are an infinite number of points in the line. Indeed, even between 4.5 and 4.6, there are an infinite number of numbers—for example 4.55 is between them, then 4.555 between 4.55 and 4.6, and 4.5555 between 4.555 and 4.6, et cetera. In all of these cases, the mathematical reality takes on a very peculiar character when you consider it in the abstract. However, the concrete triangle remains very tangible and ordinary. Likewise, 4.6 and 4.5 inches still have 0.1 inches between them. Nevertheless, in the abstract, mathematical realities are quite strange, even stranger then the idea of “a tiger in general.”

What is meant by the underlined selection, "Her sight is aimed at"?

Adapted from "The Man-Like Apes" by T. H. Huxley in A Book of Natural History (1902, ed. David Starr Jordan)

The orangutan is found only in Sumatra and Borneo, and is common in either of these islands—in both of which it occurs always in low, flat plains, never in the mountains. It loves the densest and most sombre of the forests, which extend from the seashore inland, and thus is found only in the eastern half of Sumatra, where alone such forests occur, though, occasionally, it strays over to the western side. On the other hand, it is generally distributed through Borneo, except in the mountains, or where the population is dense. In favorable places the hunter may, by good fortune, see three or four in a day.

Except in the pairing time, the old males usually live by themselves. The old females and the immature males, on the other hand, are often met with in twos and threes, and the former occasionally have young with them, though the pregnant females usually separate themselves, and sometimes remain apart after they have given birth to their offspring. The young orangs seem to remain unusually long under their mother’s protection, probably in consequence of their slow growth. While climbing, the mother always carries her young against her bosom, the young holding on by the mother’s hair. At what time of life the orangutan becomes capable of propagation, and how long the females go with young is unknown, but it is probable that they are not adult until they arrive at ten or fifteen years of age. A female which lived for five years at Batavia had not attained one-third the height of the wild females. It is probable that, after reaching adult years, they go on growing, though slowly, and that they live to forty or fifty years. The Dyaks tell of old orangs that have not only lost all their teeth, but which find it so troublesome to climb that they maintain themselves on windfalls and juicy herbage.

What does the author most nearly mean when he says “On the other hand, it is generally distributed through Borneo, except in the mountains, or where the population is dense”?

Adapted from "How Animals Spend the Winter" by W. S. Blatchley in A Book of Natural History (1902, ed. David Starr Jordan)

One of the greatest problems that each of the living forms about us has had to solve, during the years of its existence on earth, is how best to perpetuate its kind during that cold season that once each year, in our temperate zone, is bound to come. Many are the solutions to this problem. Each form of life has, as it were, solved it best to suit its own peculiar case, and to the earnest student of Nature there is nothing more interesting than to pry into these solutions and note how varied, strange, and wonderful they are.

To fully appreciate some of the facts mentioned below it must be borne in mind that there is no such thing as “spontaneous generation” of life. Every cell is the offspring of a pre-existing cell. Hence every weed that next season will spring up and provoke the farmer’s ire, and every insect that will then make life almost intolerable for man or beast, exists throughout the winter in some form.

Beginning with the earthworms and their kindred, we find that at the approach of winter they burrow deep down where the icy breath of the frost never reaches, and there they live, during the cold season, a life of comparative quiet. That they are exceedingly sensitive to warmth, however, may be proven by the fact that when a warm rain comes some night in February or March, thawing out the crust of the earth, the next morning reveals in our dooryards the mouths of hundreds of the pits or burrows of these primitive tillers of the soil, each surrounded by a little pile of pellets, the castings of the active artisans of the pits during the night before.

If we will get up before dawn on such a morning we can find the worms crawling actively about over the surface of the ground, but when the first signs of day appear they seek once more their protective burrows, and only an occasional belated individual serves as a breakfast for the early birds.

What does the author mean when he says there is “no such thing as the spontaneous generation of life"?

Adapted from "The Greatest Sea-Wave Ever Known" by R. A. Proctor in Wonders of Earth, Sea, and Sky (1902, ed. Edward Singleton Holden)

It was at Arequipa, at the foot of the lofty volcanic mountain Misti, that the most terrible effects of the great earthquake were experienced. Within historic times, Misti has poured forth no lava streams, but that the volcano is not extinct is clearly evidenced by the fact that in 1542 an enormous mass of dust and ashes was vomited forth from its crater. On August 13th, 1868, Misti showed no signs of being disturbed. So far as the volcanic neighbor was concerned, the forty-four thousand inhabitants of Arequipa had no reason to anticipate the catastrophe which presently befell them.

At five minutes past five, an earthquake shock was experienced, which, though severe, seems to have worked little mischief. Half a minute later, however, a terrible noise was heard beneath the earth; a second shock more violent than the first was felt, and then began a swaying motion, gradually increasing in intensity. In the course of the first minute, this motion had become so violent that the inhabitants ran in terror out of their houses into the streets and squares. In the next two minutes, the swaying movement had so increased that the more lightly built houses were cast to the ground, and the flying people could scarcely keep their feet. "And now," says Von Tschudi, "there followed during two or three minutes a terrible scene. The swaying motion changed into fierce vertical upheaval. The subterranean roaring increased in the most terrifying manner; then were heard the heart-piercing shrieks of the wretched people, the bursting of walls, the crashing fall of houses and churches, while over all rolled thick clouds of a yellowish-black dust, which, had they been poured forth many minutes longer, would have suffocated thousands." Although the shocks had lasted but a few minutes, the whole town was destroyed. Not one building remained uninjured, and there were few that did not lie in shapeless heaps of ruins.

The underlined phrase “So far as the volcanic neighbor was concerned, the forty-four thousand inhabitants of Arequipa had no reason to anticipate the catastrophe which presently befell them” could best be rephrased as __________.

Adapted from "The Stars" by Sir Robert S. Ball in Wonders of Earth, Sea, and Sky (1902, ed. Edward Singleton Holden)

We are about to discuss one of the grandest truths in the whole of nature. We have had occasion to see that this sun of ours is a magnificent globe immensely larger than the greatest of its planets, while the greatest of these planets is immensely larger than this earth; but now we are to learn that our sun is, indeed, only a star not nearly so bright as many of those that shine over our heads every night. We are comparatively close to the sun, so that we are able to enjoy its beautiful light and cheering heat. Each of those other myriads of stars is a sun, and the splendor of those distant suns is often far greater than that of our own. We are, however, so enormously far from them that they appear dwindled down to insignificance.

To judge impartially between our sun or star and such a sun or star as Sirius, we should stand halfway between the two; it is impossible to make a fair estimate when we find ourselves situated close to one star and a million times as far from the other. After allowance is made for the imperfections of our point of view, we are enabled to realize the majestic truth that the sun is no more than a star, and that the other stars are no less than suns. This gives us an imposing idea of the extent and magnificence of the universe in which we are situated. Look up at the sky at night—you will see a host of stars; try to think that every one of them is itself a sun. It may be that those suns have planets circling round them, but it is hopeless for us to expect to see such planets. Were you standing on one of those stars and looking towards our system, you would not perceive the sun to be the brilliant and gorgeous object that we know so well. If you could see it at all, it would merely seem like a star, not nearly as bright as many of those you can see at night. Even if you had the biggest of telescopes to aid your vision, you could never discern from one of these bodies the planets which surround the sun; no astronomer in the stars could see Jupiter, even if his sight were a thousand times as powerful as any sight or telescope that we know. So minute an object as our Earth would, of course, be still more hopelessly beyond the possibility of vision.

In the underlined sentence “We are, however, so enormously far from them that they appear dwindled down to insignificance,” the author is most nearly saying __________

Adapted from “Comets” by Camille Flammarion in Wonders of Earth, Sea, and Sky (1902, ed. Edward Singleton Holden)

The history of a comet would be an instructive episode of the great history of the heavens. In it could be brought together the description of the progressive movement of human thought, as well as the astronomical theory of these extraordinary bodies. Let us take, for example, one of the most memorable and best-known comets, and give an outline of its successive passages near the Earth. Like the planetary worlds, comets belong to the solar system, and are subject to the rule of the Star King. It is the universal law of gravitation which guides their path; solar attraction governs them, as it governs the movement of the planets and the small satellites. The chief point of difference between them and the planets is that their orbits are very elongated, and instead of being nearly circular, they take the elliptical form. In consequence of the nature of these orbits, the same comet may approach very near the sun, and afterwards travel from it to immense distances.

Thus, the period of the Comet of 1680 has been estimated at three thousand years. It approaches the sun, so as to be nearer to it than our moon is to us, whilst it recedes to a distance 853 times greater than the distance of the Earth from the sun. On the 17th of December, 1680, it was at its perihelion—that is, at its greatest proximity to the sun; it is now continuing its path beyond the Neptunian orbit. Its velocity varies according to its distance from the solar body. At its perihelion it travels thousands of leagues per minute; at its aphelion it does not pass over more than a few yards.  

Its proximity to the Sun in its passage near that body caused Newton to think that it received a heat twenty-eight thousand times greater than that we experience at the summer solstice, and that this heat being two thousand times greater than that of red-hot iron, an iron globe of the same dimensions would be fifty thousand years entirely losing its heat. Newton added that in the end, comets will approach so near the sun that they will not be able to escape the preponderance of its attraction, and that they will fall one after the other into this brilliant body, thus keeping up the heat which it perpetually pours out into space. Such is the deplorable end assigned to comets by the author of the Principia, an end which makes De la Brétonne say to Rétif: "An immense comet, already larger than Jupiter, was again increased in its path by being blended with six other dying comets. Thus displaced from its ordinary route by these slight shocks, it did not pursue its true elliptical orbit; so that the unfortunate thing was precipitated into the devouring centre of the Sun." "It is said," added he, "that the poor comet, thus burned alive, sent forth dreadful cries!"

What does the author most nearly mean when he says “Like the planetary worlds, comets belong to the solar system, and are subject to the rule of the Star King.”?