and snail, we have a simple pouch excavated in the body of the animal, opening externally by an orifice distinct from the mouth, and generally at a distance from it; and, on the inner surface of this cavity, the vessels ramify by which the blood is carried to and from the atmospheric influence. a portion of the spiders we find a similar arrangement, but the pouches are more numerous, and the interior is more or less subdivided, so as to increase the amount of surface. Among the rest of the spiders, and in the whole class of insects, the respiratory organs consist of a series of minute and highly ramified tubes, which traverse every portion of the body, so that the air performs a circulation similar to that of the blood in the higher classes. Among the vertebrate classes, the reptiles have lungs constructed with the greatest degree of simplicity, consisting of large and hollow pouches, the surface of which is slightly subdivided into cells; such is the case with the frogs, the serpents, the lizards, and the tortoises. Those which frequent the water have large lungs, containing more air than is necessary for their immediate use, and serving as reservoirs, from which oxygen is procured while they lie concealed beneath the surface. In birds and quadrupeds, whose temperature is much higher than that of the preceding classes, and the activity of whose muscular, nervous, and circulating systems is also greater, we find lungs of the highest degree of complication, the whole interior being divided and subdivided so as to secure the greatest possible amount of respiratory surface. There is still another race of animals, which, though truly aquatic in their habits, occupy a position intermediate between the two divisions above mentioned. They constitute the order of true amphibious animals, being provided with internal pulmonary organs, and with external tufts or gills, so that they are capable of respiring either air or water. This is the case with the Proteus, the Siren, and the Axolotl. Some of the lower orders of reptiles, in their immature condition, have the same organization as the Proteus, which is intended, however, only for temporary use, the gills subsequently disappearing, but the lungs continuing to be developed, and, in the adult, the function being performed as in other air-breathing animals. The tadpole of the common frog is thus organized, the gills not disappearing until it undergoes its metamorphosis, when its extremities are fully developed, and it becomes capable of terrestrial loco motion. Having thus given a general view of the respiratory organs, as presented by the different classes, the author proceeds to an exposition of the effects of respiration; namely, its action upon the atmosphere, or upon the air contained in the water, the comparative amount of oxygen consumed, and carbonic acid exhaled, by man and the lower animals, the changes which the blood undergoes in its circulation through the respiratory organs, the causes of its change of color, in a portion of the animal kingdom, during its passage from the venous to the arterial system, and the theory of the chemical process. Lastly, he treats of the respiratory motions, and of the influence of the nerves on the different stages of the respiratory function. Having passed in review the different theories which have been advanced from time to time by Lavoisier, Laplace, Davy, and others, he sums up the present state of our knowledge on this subject as follows: "Till within the last few years, therefore, the theory of respiration was involved in inexplicable difficulties. Blood agitated with atmospheric air was known to yield carbonic acid without the influence of the living organ, becoming at the same time of a bright red color; it was believed, however, to contain no preexisting carbonic acid; and yet frogs were found to exhale carbonic acid when no oxygen was respired, and in nearly as large a quantity as in atmospheric air. "Now, however, the problem is satisfactorily solved. The excellent experiments of Professor Magnus have shown that both kinds of blood contain oxygen, nitrogen, and carbonic acid gas, that arterial blood contains more oxygen than venous blood, while carbonic acid is in larger quantity in the venous than in the arterial. During respiration, carbonic acid is extracted from the blood by the atmospheric air, oxygen being yielded to the blood in its place; a portion of the carbonic acid still remains, however, dissolved in the arterial blood. In the process which is constantly going on between the blood and the texture of the organs in the capillary vessels of the body, the oxygen, which is a vivifying stimulus for the organized substance, disappears in part from the arterial blood, and carbonic acid is formed; the venous blood, therefore, contains a larger proportion of carbonic acid, though it retains some of the oxygen. The venous blood reaching the lungs is again deprived of a part of its carbonic acid by the action of the atmospheric air. The interchange of the carbonic acid and oxygen in the lungs is wholly in accordance with the physical laws of the absorption of gases. A fluid impregnated with a particular gas does not give it out as long as its surface is subjected to the pressure of the same gas; but, if it is brought into contact with a different gas, an interchange takes place until the gas with which the fluid is impregnated, and the gaseous atmosphere which presses upon it, are equally mixed. This law affords a ready explanation for the exhalation of carbonic acid by frogs in hydrogen and nitrogen in as large quantity as in atmospheric air, as well as for the fact that hydrogen and nitrogen transmitted through blood become impregnated with the carbonic acid which it contains. "The proportion of carbonic acid contained in the blood is sufficiently large to account for the whole quantity exhaled from the lungs. "Supposing that two ounces of blood are expelled from the heart at each beat, ten pounds must pass through the lungs in a minute; and these ten pounds of blood ought to contain 27-4 cubic inches of carbonic acid, such being the volume of this gas which Allen and Pepys found to be exhaled from the lungs during a minute's respiration. But, admitting that the quantity of carbonic acid really exhaled from the lungs is less by one half than the experiments of Allen and Pepys would indicate, -and it certainly is less, and adopting the estimate of Sir H. Davy, who calculated that 158 cubic inches is the amount of carbonic acid gas exhaled from the lungs during each minute, still ten pounds of blood ought to contain nearly sixteen cubic inches of that gas. "The experiments of Professor Magnus have shown, that the blood contains at least one fifth of its volume of carbonic acid; and, since one pound of blood measures about 25 French cubic inches [one pound avoirdupois of water contains 27.7 English cubic inches, the same weight of blood about 26-4 English cubic inches], every pound of venous blood ought to contain at least five cubic inches of carbonic acid, and the ten pounds of blood which pass through the lungs in a minute, 50 cubic inches [60 English cubic inches], of which it may easily be conceived that 15.8, or even 27-4 cubic inches, may be exhaled in the respiratory process. "A small quantity of nitrogen is absorbed by the blood from the air respired, but does not appear to perform any office in the system, since its proportion is the same in arterial and venous blood. "The object of the respiratory process is evidently, first, the absorption of oxygen into the blood, which conveys that gas as a stimulus to the different organs of the body; and, secondly, the removal from the blood of the carbonic acid which is formed in the capillaries. That the latter is not the main object is clearly shown by the fact of frogs falling into a state of asphyxia when made to respire in hydrogen and nitrogen, although the quantity of carbonic acid which is exhaled in those gases is not in the slightest degree less than in atmospheric air.” — Vol. 1. pp. 357, 358. We are aware that it is impossible, from a short notice like this, to form a true idea of the whole work under consideration; to this end, nothing short of attentive study will suffice. The student who shall avail himself of the treasures contained in it, will be convinced that Professor Müller, as might have been anticipated from his high European reputation, was eminently qualified for the great task which he has undertaken; and that, before entering upon his labors, he had acquired all the preliminary information essential to his success. He has a thorough acquaintance with physical and chemical science, and the anatomy of man and the animal races; and to these qualifications must be added an acute and philosophical mind, slow to admit the opinions of others, unless supported by substantial evidence. Nearly every page affords sufficient testimony of the truth of what is here advanced. We do not wish to imply, that no objectionable opinions are brought forward; some there certainly are, perhaps many; to discuss these in detail, however, is a business that falls within the province of journals strictly devoted to medical and physiological science. With With regard to the English edition of this work, we have no other remark to make than that it is in the highest degree satisfactory, not merely from the beauty of its typographical execution, but on account of the numerous marginal illustrations and diagrams, which are indispensable for a clear understanding of many portions of the text. respect to the American edition, although we are by no means disposed to doubt the ability of its editor, or that he has performed his duty as faithfully as the circumstances would admit, we think that it is much to be regretted that any abridgment should be undertaken, especially since it often requires, as in the present case, the omission of im portant evidence, and the insertion of general and imperfect summaries. The absence of engraved illustrations in the body of the text must be regarded as a great objection to the American abridgment, and, should a new edition be called for, we trust that it will be found practicable to supply them. ART. VI. History of Europe, from the Commencement of the French Revolution in 1789, to the Restoration of the Bourbons in 1815. By ARCHIBALD ALISON, F. R. S. E., Advocate. Paris Baudry. : 10 vols. 8vo. 1841. MR. ALISON'S History has many excellent qualities, and some striking faults. It is the elaborate and highly finished work of an able and conscientious writer, who has given to it the patient toil of many years, and who may be considered as having staked his reputation upon its success. It is not a brilliant production; it does not bear the marks of genius; it is not imbued with any profound philosophy. But it is full of interest, and it embodies a great amount of information, carefully collected, and admirably digested and arranged, and presented in a way that cannot fail to absorb the attention of the reader. It is conceived on a comprehensive plan, which admits every thing that can elucidate the main subject, without violating its unity; and it is executed with a care, fidelity, and spirit, that cannot be too highly appreciated. The author endeavours to be strictly impartial, and he is generally successful in the attempt. His work contrasts very favorably, in this respect, with the Life of Napoleon, by Scott, which is so full of English prejudices and unfairness, that, notwithstanding the great merits of its execution, it can hardly be said to possess any historical value whatever. This remarkable book always appeared to us like a sort of high Tory romance, or a plea in favor of Castlereagh politics, illustrated by a half fabulous account of French Jacobinism and the crimes of Napoleon. Mr. Alison's work has far higher claims to consideration and trust. Yet his Tory principles are as violent, and carried as far, as |
