then prepared for being swallowed, which the creature accomplishes by pushing the limbs into the most convenient position, and then covering the surface with a glutinous saliva. The reptile commences the act of deglutition by taking the muzzle of the prey into its mouth, which is capable of vast extension; and, by a succession of wonderful muscular contractions, the rest of the body is gradually drawn in, with a steady and regular motion. As the mass advances in the gullet, the parts through which it has passed resume their former dimensions, though its immediate situation is always betrayed by external protuberance.-As already mentioned, the species of boa are peculiar to the hot parts of South America, though nothing is more common than the error of confounding the great serpents of India, Africa, &c. with the proper boa. According to the researches of Cuvier, all the boe, at present well determined, are natives of the new continent. The great serpents of the old continent belong to the genus python. It is nevertheless true, that Pliny has spoken of the huge serpents of India, and afterwards of large serpents of Italy, which were called boe, thus named from the circumstance of their being at first fed with cow's milk.Among the most celebrated species is the boa constrictor, distinguished by a large chain, formed alternately of large, blackish, irregular hexagonal spots, with pale, oval spots, notched at their two extremities, along the back. This is the largest species, and is usually confounded, by casual observers, with the python Tigris of the old world. The Boa cenchris, and the Boa scytale, et musina, attain to nearly an equal size with the constrictor (from 20 to 30 feet long,) and are all natives of the torrid and marshy regions of America. The other species are of smaller size, and some do not much exceed that of the largest common snakes. We cannot reflect upon the natural history of these great reptiles, without being struck with their peculiar adaptation to the situations in which they are commonly most abundant. In regions bordering on great rivers, which, like the Orinoco, &c. annually inundate vast tracts of country, these serpents live securely among the trees with which the soil is covered, and are capable of enduring very protracted hunger without much apparent suffering or diminution of vigor. Noxious as such districts are to human life, they teem with a gigantic and luxuriant vegetation, and are the favorite haunts of numerous animals, preyed upon, and, to a certain degree, restricted in their increase, by the boa. As their prey come within their reach, they require no deadly apparatus of poison to produce their destruction, since nature has endowed them with muscular strength surpassing that of almost every other crea ture, in proportion to their size. Once fairly involved in the crushing folds of the constrictor, the strength of the strongest man would not prove of the slightest avail; indeed, from the ease with which larger and more powerful creatures are put to death by these serpents, it is evident that any number of unarmed men would act very unwisely to provoke a combat with enemies endowed with of such dreadful energy. powers VEGETABLE SUBSTANCES-THE COW TREE. Mr. Humboldt, in his Personal Narrative gives the following account of this wonder of the vegetable world. Amid the great number of curious phenomena which have presented themselves to me in the course of my travels, I confess there are few that have so powerfully affected my imagination, as the aspect of the cow tree— Whatever regards corn, inspires an interest, which is not merely that of the physical knowledge of things, but is connected with another order of ideas and sentiments. We can scarcely conceive how the human race could exist without farinaceous substances, and without that nourishing juice which the breast of the mother contains, and which is appropriated to the long feebleness of the infant. The amylaceous matter of corn, the object of religious veneration among so many nations, ancient and modern, is diffused in the seeds and deposited in the roots of vegetables-milk, which serves us as an aliment, appears to us exclusively the produce of animal organization. Such are the impressions we have received in our earliest infancy; such is also the source of that astonishment which seizes us at the aspect of the tree just described. It is not here the solemn shades of forests, the majestic course of rivers, the mountains wrapped in eternal frosts, that excite our emotion. A few drops of vegetable juice recall to our minds all the powerfulness and fecundity of nature. On the barren flank of a rock grows a tree with coriaceous and dry leaves. Its large woody roots can scarcely penetrate into the stone. For several months of the year not a single shower moistens its foliage. Its branches appear dead and dried; but when its trunk is pierced, the flows from it a sweet and nourishing milk. It is at th rising of the sun that this vegetable fountain is most abundant. The blacks and natives are then seen hastening from all quarters; furnished with large bowls to receive the milk, which grows yellow, and thickens at its surface. Some employ their bowls under the tree itself, others carry the juice home to their children. We seem to see the family of a shepherd, who distributes the milk to his flock. I have described the sensation which the cow tree awakes in the mind of the traveller, at the first view. In examining the physical properties of animal and vegetable products, science displays them as closely linked together; but it strips them of what is marvellous, and perhaps also of a part of their charms, of what excited our astonishment. Nothing appears isolated, the chemical principles that were believed to be peculiar to animals are found in plants, a common chain links together all organic nature. NOTICES OF RECENT PUBLICATIONS. Life of Sir Isaac Newton, by Dr. Brewster. Being the twenty-sixth number of Harper's Family Library. Few species of writing are more attractive than Biography, and of late years, few have been more popular. So eager is the general curiosity to learn every thing calculated to throw light upon the characters of those who have been distinguished among their fellow men, that none who have filled any space in the public eye are suffered to pass away with their history unrecorded. Nor is the death of the individuals a necessary preliminary. We have the lives of heroes, orators and statesmen who are still in the midst of their usefulness. Still ready to lead our armies to victory, still able to charm our senates with their eloquence and to guide the councils of our nation with their wisdom. Such being the case, we hazard little in saying that the present number will be as exten sively circulated as any of its predecessors; for in it we find a full and satisfactory account of the life of one whose name has long 'been first upon the roll of fame. The claims of other men are open to dispute. The soldier may hesitate between Cæsar and Napoleon, while the votary of literature deems it sacrilege to name either in a breath with Milton, Locke, or Shakspeare, but he too would hesitate to which of that glorious band he should yield the preference. Mention the name of Newton, and each at once acknowledges his preeminence and bows the head in reverence of his genius. He is one whom all agree to venerate, for the benefits he has conferred upon his race, are so unmixed with aught of a countervailing tendency, that all must unite in regarding him as a benefactor. In the present volume we trace this illustrious character from the cradle to the grave. We find him in early boyhood evincing his taste for practical mechanics in the construction of ingenious toys; and in his windmills, his sundials, his locomotive carriages and water clocks, we perceive the dawning of that restless and inquiring mind, which afterwards discovered and investigated the mechanical laws that regulate the motions of the universe. We see him in youth advancing step by step, in the laborious aequisition of knowledge, and laying stone on stone, the sure foundation of his future usefulness, till in his twenty-seventh year we find him in the mathematical chair of the university. We have an able account of his theory of colors and of his successive discoveries in optics and the properties of light, drawn up by Dr. Brewster, himself one of the most learned philosophers in Europe and especially conversant with this department of science; we are also presented with an abstract of his astronomical discoveries, together with a sketch of the history of astronomy previous to his time, including the immortal labors of COPERNICUS, TYCHO BRAHe, Kepler and GALILEO. We now come to the glorious discovery of the law of gravity and the cause of the planetary motions; and here we will use the words of his eloquent biographer. "In the progress of the calculation, he saw that the result which he had formerly expected was likely to be produced, and he was thrown into such a state of nervous irritability that he was unable to carry on the calculation.* In this state of mind he entrusted it to one of his friends; and he had the high satisfaction of finding his former views amply realized. The influence of such a result upon such a mind may be more easily conceived than described. The whole material universe was spread out before him; the Sun with all his attendant planets; the planets with all their satellites; the comets wheeling in every direction in their eccentric orbits; and the systems of the fixed stars stretching to the remotest limits of space: all the varied and complicated movements of the heavens, in short, must have been presented to his mind, as the necessary result of the law which he had established." We will conclude this notice with one more extract from the work before us. "If the conduct and opinions of men of ordinary talent are recorded for our instruction, * See the Monthly Repository, vol. 2, page 226. how interesting must it be to follow the most exalted genius through the incidents of common life; to mark the steps by which he attained his lofty preeminence; to see how he performs the functions of the social and the domestic compact; how he exercises his lofty powers of invention and discovery; how he comforts himself in the arena of intellectual strife; and in what sentiments and with what aspirations he quits the world he has adorned. In almost all these bearings, the life and writings of Sir Isaac Newton abound with the richest counsels. Here the philosopher will learn the art by which alone he can acquire an immortal name. The moralist will trace the lineaments of a character adjusted to all the symmetry of which our imperfect nature is susceptible; and the CHRISTIAN will contemplate with delight, the high priest of science, quitting the study of the material universe, the scene of his intellectual triumphs, to investigate with humility and patience, the mysteries of his faith." POETRY & MUSIC. Written for the Monthly Repository and Library of Entertaining Knowledge, BY MRS. LYDIA H. SIGOURNEY. "MOURN FOR THE LIVING, AND NOT FOR THE DEAD." I saw an infant, marble cold Borne from the pillowing breast, They bare a coffin to its place, I ask'd them, who was there? But for that blest one do ye moan I wander'd to a new made grave, The love of Him who died to save I murmur not for those who die, |