which, in a clear and dry state of the air, the direct light produces in the more or less coloured parenchyma of the leaves and fruits. In the same mean temperature of the atmosphere, the development of vegetation is retarded or accelerated according as the sky is foggy or serene, and according as the surface of the earth receives only a diffuse light during entire weeks, or is struck by the direct rays of the sun. On the state of the atmosphere, and the degree of the extinction of light, depend, in a great measure, those phenomena of vegetable life, the contrasts of which surprise us in islands, in the interior of continents, in plains, and on the summit of mountains. If we neglect these pho tometrical considerations, and do not appreciate the production of heat in the interior of bodies, and the effect of nocturnal radiation in a clear or a cloudy sky, we shall have some difficulty in discovering, from the numerical ratios of the observed summer and winter temperatures of Paris and London, the causes of the striking difference which appears in France and England in the culture of the vine, the peach, and other fruit-trees.*

When we study the organic life of plants and animals, we must examine all the stimuli or external agents which modify their vital actions. The ratios of the mean temperatures of the months are not sufficient to characterize the climate. Its influence combines the simultaneous action of all physical causes; and it depends on heat, humidity, light, the electrical tension of vapours, and the variable pressure of the atmosphere. It is the last cause which, on the tops of mountains, modifies the perspiration of plants, and even increases the exhaling organs. In making known the empirical laws of the distribution of heat over the globe, as deducible from the thermometrical variations of the air, we are far from considering these laws as the only ones necessary to resolve all the problems of climate. Most of the phenomena of nature present two distinct parts,-one which may be subjected to exact calculation, and another which cannot be reached but through the medium of induction and analogy.

* YOUNG'S Travels in France, vol. ii. p. 195.

CRITICAL ANALYSES

OF

RECENT PUBLICATIONS, IN THE DIFFERENT BRANCHES OF MEDICINE AND SURGERY.

"I would have men know, that, though I reprehend the easie passing over of the causes of things by ascribing them to secret and hidden vertues and properties; (for this hath arrested and laid "asleepe all true enquiry and indications;) yet I doe not understand but that, in the practical "part of knowledge, much will be left to experience and probation, whereunto indication cannot so fully reach: and this not only in specie, but in individuo. Yet it was well said, Vere scire "esse per causas scire."-BACON.

Elements of Medicul Logick, illustrated by Practical Proofs and Examples. The Second Edition, with large Additions, particularly in the Practical Part. By Sir GILBERT BLANE, Bart. Fellow of the Royal Societies of London, Edinburgh, and Göttingen; Member of the Imperial Academy of Sciences of St. Petersburgh; and Physician to the King. 8vo. pp. 265. T. and G. Underwood, London, 1821.

A

RECENT French critic, speaking of a new edition of SCARPA's work on Diseases of the Eye, very properly observes of it" Que ce n'est point de ces editions que la su percherie de nos libraires fabrique en recomposant la feuille du titre." Precisely the same remark may be made respecting the new edition of the work before us; for, it is not only enlarged by many useful, and in some points necessary, additions, but is judiciously modified, as we are convinced, throughout the greater part of its former arrangement. The author himself, indeed, in the advertisement prefixed to the new edition, states, that he felt bound, in gratitude and duty, from the success of the first impression, in 1819, to render the present one still more worthy of public acceptance, by large additions.

Logic, as one of the moral sciences, has been so much perverted by the schoolmen, that the very name of it excites a smile. BACON was so convinced of this, that he studiously avoided the very name of logick, and either substituted for it the synonym dialectic, or employed his own quaint peryphrasis "novum organum."

In undertaking the present work, our author has attempted to restore logic to its original dignity and utility; and, when we consider how important it is to those who are to practise physic, that they should possess the means of disciplining their minds to the right investigation of truth,-the profession will feel obliged to Sir Gilbert for having endeavoured to extend the art of discriminating good from bad evidence, to a branch of natural knowledge essentially beset with every species of fallacy.'

That such is the nature of the obligation we owe to Sir Gilbert Blane, may indeed be collected from his own declared purpose, with which the introduction terminates:

"It is the author's intention, with unfeigned diffidence and humility, to endeavour to point out in what medical truth and error consist; what are the difficulties that have obstructed the progress of the art, and what are the means of obviating them: in other words, (if he may be allowed to adopt professional technology,) to expound the. physiology, pathology, and therapeutics of the medical mind, as the result of fifty years' observation, experience, and meditation, on these subjects."

In the preliminary remarks, the author has entered into a concise metaphysical inquiry into the faculties of the mind employed in ascertaining those truths which depend on correct observation and a right interpretation of the works of nature. He asserts, in common with some other authors, that the senses may be considered as the types of universal nature; and he further remarks, that there is a like accordance with the faculties of the mind, particularly that part of the mental constitution by which we are made susceptible of habit and association.

"In tracing this still farther, we perceive that, by virtue of this correspondence or co-ordinance of the frame of the mind with the established course of nature, there is, in all the changes produced by the action of external bodies on each other and on our own bodies, a rapid and instinctive connexion between cause and effect, manifested in that part of our constitution by which it is made susceptible of habit and association, and which is indispensable to our well-being, and even our existence, particularly in early life. This may literally, and without a figure of rhetoric, be termed the mental organ; for it carries a reference to the constancy of nature, just as the eye does to the affections of light, and the ear to those of the air. Thus is every organ and function of the body, and every faculty of the mind, co-relative with, or represents and reflects, as it were, not only the elements, but the laws, of universal nature; so that the sublime images and glories of the creation are displayed to our sensitive capacities as objects of grandeur and beauty, and to our intellectual capacities and enraptured minds as irresistible evidences of harmony and design."-P. 20-21.

In the body of the work, the author sets out with professing to follow the inductive method of investigation, as less liable to error than the syllogistic. This last, however, he does not treat with the same contempt as some other modern metaphysicians; alleging, that it tends to give precision to language and thought, and to induce habits of close attention and patient ap

See this sentiment more fully illustrated in a Lecture on Muscular Motion, page 40, read before the Royal Society, 1788, by GILBERT BLANE, M.D. It is also ingeniously and appositely alluded to in Mad. DE STAEL'S account of the German poetry, in the work entitled Del Allemagne, 1815.

plication of mind;" at the same time lamenting that it should have superseded all other learning, for more than one thousand years, in the schools of Europe.

He next enters into a comparison of the different degrees of certainty and of difficulty in the ascertaining of truth in physi cal researches. Of these, Sir Gilbert thinks that chemistry is the most exact, so that a single experiment may ascertain a general truth, there being only one affecting cause, namely affinity whereas, in mechanical philosophy, and still more in all that relates to organic nature, there is a combination of many causes, which more or less tend to modify the results. With a view to such researches, therefore, he alleges, that all these causes, whether concurring or counteracting, should be specified. This, the author contends, has never been done; and he therefore attempts it, by enumerating the principles which belong exclusively to animal life, and which he not unaptly designates as the alphabet, or elementary constituents, of physiology and pathology. These elementary principles are ten in number:-1, The Generative; 2, the Conservative; 3, the Temperative; 4, the Assimilative; 5, the Formative; 6, the Restorative; 7, the Motive; 8, the Sensitive; 9, the Appetitive; 10, the Sympathetic.'

To follow our author through his detailed illustrations of each of the above principles, would be, in a great measure, to travel over the same ground we did on a former occasion, when we reviewed the first edition. We cannot, however, deny the public and ourselves the pleasure of noticing a few of the many facts and observations, some new, and some more happily demonstrated than heretofore, with which the body of the present edition abounds, and which we find arranged under the different subdivisions that treat of the elementary principles. Thus, under the "generative," there are some curious remarks of the steady proportion of the sexes, in spite of the great inequalities of individual procreation; and, in speaking of the "conserva tive" principle, Sir Gilbert remarks, that, though one of the fundamental principles of life, it has been strangely neglected, and even entirely overlooked, by some physiologists. As for the attempt made by several of them to account for this curious principle by the perpetual motion of the living fluids and solids, the author considers it as futile in the extreme. We have, under the "temperative" principle, considerable additions of importance, particularly where the author combats those opinions which assign a chemical origin to animal heat. On this subject, Sir Gilbert's remarks are worthy of attention.

"The standard of heat is very different in different species of animals. In the amphibia and fishes, it is very little above that of the surrounding medium. But the resistance which these animals give

both to heat and cold, by maintaining their specific temperature in apite of the application of higher or lower degrees of it, contrary to the law of communication in inanimate bodies, is a proof that temperature is both raised and depressed by some power essentially inherent in life. This is most observable in birds; for, in those even of the smallest size, the natural heat is ten or twelve degrees above the human. When it is considered how immeasurably greater the abstracting power of the atmosphere is in these small bodies, in consequence of the ratio of their surface being as the square of their mass, it is utterly impossible to account for this on chemical principles, and must depend on a specific generating power, furnished in various degrees to the respective species of animals; and it must be astonishingly great in small animals, to enable them to resist the strong power of abstraction in the external medium. This argument is rendered still more strong by what is found to take place with regard to some insects. Let the bulb of a thermometer be thrust into a swarm of bees, the heat indicated will be 97° or 98°, that is, as high as that of the living human body.-P. 43-44.

We also wish to recommend to our readers a number of other remarks on temperature, physiological, pathological, and practical, with which this part of the work abounds, and many of which are new.

It is under the appellation of " assimilative" principle that the author has grouped the two physiological functions of digestion and secretion. Here Sir Gilbert enters at full length into the changes produceable by the sole power of animal life, as distinguished from the chemistry of dead matter; alleging that, from the similarity of animal matter in all animals, whatever their food may be,-also from the experiments of Allen and Pepys on respiration,-the power of life in producing, or rather creating, new modifications of matter, is far more considerable than has been commonly allowed. Sir Gilbert takes occasion also to advert to the question respecting the influence of the nerves in modifying digestion and temperature, and seems unwilling to admit it in the sense and to the extent of some other physiologists; grounding his opinion, not only on what occurs in animals without brain and nerves and in vegetables, but on a distinction also which should be made between an actuating and an influential, or intervening, cause.

In a book of so much merit, and one which for reasoning power has seldom been surpassed, we are, of course, anxious that nothing should wear the appearance of wrong induction. An instance, however, of want of rectilineal induction, as it appears to us, occurs under the very head of which we have just given an analysis, and relates to the author's individual opinion regarding the influence of nervous action on the assimilating process. The author alleges, first, that "nervous power is found, in some instances, even to retard and disturb the assimilating process;" and