are occupied in building up rocks, in comparison with the work of which, the labor of the plants we have considered may be called insignificant. The diatoms, which live in fresh and salt waters, are the smallest of all organisms. They were once thought to be animals, but are now regarded as plants, and are one-celled structures which have the property of sucking up large quantities of carbonic acid from the water and storing it in their cell-walls. They increase by repeated divisions and subdivisions of their cells, and build up rocks by their simple presence. They multiply with such prodigious rapidity, and the number of their genera and species is so great, that under favorable conditions, as in the shallows and muddy flats of the seashores and in wet places in the interior, they contribute the substance of whole strata by leaving behind them when they die their silicated cell-walls, which become consolidated with the earthy materials into a harder or softer rock-formation. The magnitude of the operations of this kind that are going on in the present epoch is illustrated in the Lüneberg heath, where the diatomaceous formation is more than thirty feet thick. The city of Berlin is built upon a bed of clay of from six to one hundred feet thick, two thirds of the mass of which consist of diatoms. There is a puzzling feature in the life of these diatoms. They contain a coloring matter, diatomin, which is similar to chlorophyl in its properties and in having the power of abstracting carbonic acid from the air and water. It is hard to understand how this power can be exercised where the light does not penetrate. Yet a great mass of the diatom bed under Berlin is living and active, and streets and houses have been disturbed by its growth. The functions which the diatoms perform in the present history of the earth were also exercised by them during the earliest epochs of which we know, and probably in still earlier times.
Intelligence of a Pet Monkey.—A writer in "Chambers's Journal" vouches for the truth of the following story about a pet monkey, which, even if taken with many grains of allowance, exhibits a remarkable degree of intelligence that, in many respects, seems scarcely less than human: "Peter" belonged to an officer in the British Army, and was a large and powerful specimen of his class. He was a general favorite, his unusual sagacity and varied accomplishments forming a source of endless amusement, and, although somewhat mischievous, his gentleness of disposition and genuine love of fun readily secured forgiveness for occasional annoying pranks. Unfortunately, however, Peter had an enemy in the person of a diminutive and unpopular subaltern, to whom he appears, in some mysterious way, to have rendered himself particularly obnoxious. During a temporary absence of his master the monkey was intrusted to the care of a brother officer, who, being anxious that he should suffer no harm, chained him to a chest of drawers in his own room. This well-meant restraint did not coincide with Peter's desire for freedom, and, left to his own resources, he sought about for some means of diversion. Having first forced open the locks of all the drawers, he strewed their contents upon the floor, and seated himself in the midst, "monarch of all he surveyed." Next, discovering an inkstand within reach, he bedaubed with its contents every article belonging to his hospitable entertainer. When his host returned, Peter appeared totally unconscious of having been guilty of the slightest misdemeanor. He was not punished, but summarily dismissed from his comfortable quarters and allowed to wander freely about the barracks. All went well for a time, but, later in the course of one of his rambles, Peter unluckily encountered his enemy, and, springing upon the shoulder of the irate and alarmed subaltern in the presence of a large number of officers and men, he nearly succeeded in drawing the sword of his victim, who, according to report, was not at all likely to draw it himself. The ludicrous position of the latter, amid the loud laughter of the men, served only to increase the subaltern's hatred of the popular monkey. Shortly after this, Peter was fired at and seriously injured. Though it was impossible to prove who was guilty of this cowardly act, it was naturally attributed to the subaltern, who, it was well known, had never forgiven the indignity inflicted upon him in public. Peter's friends exerted themselves to save his life;
