found a rod dipped in hydrochloric acid give white fumes when held near the cutaneous surface.

Thus it would seem that while the presence of a certain amount of ammonia in the blood is not only a normal condition, but is absolutely essential to the continuance of its fluidity, there is a provision in the pulmonary and cutaneous exhalation for the removal of any excess imparted to it by an acceleration of the ordinary rate of decomposition, as a consequence either of excessive exertion or of disintegrating disease. In the Appendix to his Essay, Dr. Richardson enters upon various considerations, which seem to connect an excess or deficiency of ammonia in the blood with particular groups of morbid phenomena, and which seem to afford indications for the rational employment of acids and alkalies in the cure of disease. Into these inquiries, however, we shall not at present follow him; since the subject has been hitherto far too little elucidated to admit the establishment of any satisfactory conclusions. Thus for example, in regard to typhoid fever, it is by no means so clear as Dr. Richardson seems to suppose, that the excess of ammonia in the blood is to be regarded as the essential phenomenon of the disease; for to us it seems more likely that it is only a result of that disintegrating change in the fluids and solids of the body which is the consequence of the action of a zymotic poison upon them. Still this portion of the work is eminently suggestive; and we trust that not only by the author himself, but by many others, will observations and experiments be systematically carried on, with the view of accumulating a body of information upon these important questions, on which valid pathological principles and sound rules of practice may be securely founded.

Although we have expressed our readiness to accept the facts which Dr. Richardson appears to have conclusively established, yet we are compelled to record our dissent from some of his inferences. He seems to conceive that in showing the coagulation of fibrin to be immediately dependent upon the liberation of ammonia, he has demonstrated that this coagulation is a purely physical phenomenon; and he does not hesitate to liken it to the coagulation of albumen by heat, to the gelatinization of a solution of gelatin on cooling, and even to the formation of a film of collodion by the evaporation of its ethereal solvent. Now to us it appears that the coagulation of fibrin cannot be rightly compared with that of either of the foregoing substances; inasmuch as the coagulum which they form is homogeneous, whilst the coagulum of fibrin presents an approximation (which becomes very distinct in particular cases) to an organic structure. Dr. Richardson has, moreover, committed that very common error, of imputing causation to the last antecedent alone, instead of looking for it in the sum of all the antecedents. We may, perhaps, best illustrate our meaning by referring to the phenomena of germination. It is well known that the extrication of carbonic acid is so necessary a condition of this process, that, if it be prevented, germination will not take place; it is further well known that a certain measure of heat is requisite for germination, which may be indefinitely retarded if this heat be withheld. Yet would Dr. Richardson or any other thoughtful physiologist assert, on these accounts, that germination is a purely physical process-ignoring the fact that it essentially consists in the growth of an organized structure, and that only a seed which retains its vitality can exhibit these phenomena? The cause of germination surely does not lie simply in the application of warmth to the seed, or in the extrication of carbonic acid; these are necessary conditions of the act, as is also the presence of nutrient material stored up for the use of the germ; but a condition not less necessary is the presence of the germ, endowed with properties, which, as being peculiar to a living being, we distinguish by the epithet "vital." In like manner, the cause of the coagulation of the blood does not rest alone in the liberation of ammonia; the presence of a substance endowed with the property of passing, in the act of solidification, into a rude form of fibrous tissue, is no less essential a condition; and so far as we at present know, that substance can only be generated by the agency of a living body. Chemists are sanguine of being

able, some day or other, to manufacture albumen; and we see no reason why they may not succeed, since albumen displays no properties which can be regarded as putting it beyond the pale of pure chemistry. But until the chemist shall have effected in his laboratory the transformation of Albumen into a substance possessing the distinctive properties of Fibrin, as evidenced not merely in the spontaneous formation of a coagulum on the escape of ammonia, but in the peculiar structure of that coagulum, we must retain our conviction that this transformation can only be effected by the agency of a living organism, that it must therefore be distinguished as "vital," and that the act of coagulation is essentially a "vital" phenomenon, dependent (like every other of the same class) upon certain physical conditions. And it is no valid reply to this doctrine, to point to the length of time during which a solution of fibrin may retain its coagulating power; for the like is true in numerous other cases, in which no physiologist (so far as we are aware) hesitates to admit that vital properties may be retained for an unlimited period. How can we explain the revivification of a dried-up Rotifer on the application of moisture, or the germination of a seed buried for thousands or tens of thousands of years deep in the earth, under exposure to warmth and air, if we do not admit that vital properties may be retained in a dormant or inactive condition for indefinite periods?

There is a great tendency at the present time, amongst those who make a special study of the Physics and Chemistry of living bodies, altogether to ignore all Vital agencies; yet nothing, as it seems to us, can be more false than to attempt to resolve the latter into the former. We are willing to go as far as any one in the prosecution of the inquiry how far Physical and Chemical forces can be held to account for the phenomena presented by living bodies; but we are of opinion that no really philosophic Physiologist will seek to refer the phenomena of Assimilation and Nutrition, Growth and Development, to any other than Vital agencies acting under determinate physical conditions. As well might we say that Heat is Electricity, or that Light is Magnetism, as affirm that the duplicative subdivision of a cell is simply a physical phenomenon, or that the action of the spermatic fluid on the germ-cell is a mere chemical change. There is nothing more hypothetical in the assumption of Vital force, than in that of Electric or Magnetic force. We know no more of the intimate nature of the latter, than we do of that of the former; each can be studied only in its phenomena; and it is the first object of all inductive inquiry, to determine what are analogous or related phenomena. For the reasons we have specified, and for many more that we might adduce, we still hold to the opinion of John Hunter, that the coagulation of fibrin is essentially a vital act, being dependent on the properties which the fibrin has acquired as a constituent of a living organism; whilst we are ready to accord the highest credit to Dr. Richardson, for the important advance he has made towards the exact determination of the physical conditions under which this change occurs.

REVIEW VI.

Traité de Géographie et de Statistique Médicales et des Maladies Endémiques; comprenant la Météorologie et la Géologie Médicales, les Lois Statistiques de la Population et de la Mortalité, la Distribution Géographique des Maladies, et la Pathologie Comparée des Races Humaines. Par J. CH. M. BOUDIN, Médecin en Chef de l'Hôpital Militaire du Roule, Officier de la Légion d'Honneur.-Paris, 1857. Two vols. 8vo. pp. 576 and 764.

Treatise on the Medical Geography and Statistics of Endemic Diseases; comprising Medical Meteorology and Geology, the Statistical Laws regulating

Population and Mortality, the Geographical Distribution of Diseases, and the Comparative Pathology of the Races of Man. By J. C. M. BOUDIN, Chief Medical Officer of the Military Hospital du Roule, &c.

THE author of this comprehensive work, who holds a distinguished position among the military surgeons of France, has been long known as an indefatigable and ingenious statistician. His labours in this field have been made public in a succession of memoirs, some of the most interesting of which appeared in the 'Annales d'Hygiène,' of which he is one of the editors.

Since the publication of his 'Essai de Géographie Médicale,' in 1843, M. Bondin appears always to have intended at some future day to resume the subject, and in the interval he has spent much time in amassing materials bearing on the various questions involved. He was thus in a favourable position to accede to a request to write such a work as the present, made by his publisher, M. Baillière, who deemed it a desideratum in professional literature.

Such appears to be the history of the development of the work, for which, therefore, we have alike to thank the industry and talent of its writer, and the enterprise of its publisher. It professes to bring together all the facts which science now possesses, bearing directly or correlatively on medical geography, and to produce a framework in which future observations may be classed and arranged.

Towards the end of the last, and in the earlier part of the present century, there were several German works on the subject, and at a later date, Van der Hoeven, Fuchs, and Mühry, have been valuable contributors. In our own language, we have many well-known works on medical and vital statistics, and on climate; and our serial literature is rich in disjointed and fragmentary contributions to the study of the geography of disease, the influence of race, and the history of endemic and epidemic ailments. Indeed, it is not without a certain degree of pleasure and pride that we observe, throughout the whole of M. Boudin's work, how frequently he has to acknowledge the labours of Englishmen, and of what value to him have been the statistical reports on the army, the annual reports of the Registrar-General, and the various memoirs published by the Statistical Society of London. Scattered over the face of the earth as are the British possessions in polar, temperate, and tropical regions, in the north hemisphere and south, including such varied races of men, some in their places of birth, others moved northwards, and others southwards from it-considering these things, it is not wonderful that Great Britain should possess the richest sources of information on questions of medical geography. She holds, in fact, within herself, elements for the solution of many of the most interesting points in such researches, and it is gratifying to find, from the prominent place they occupy in M. Boudin's work, that they have not been passed by unnoted by our army, navy, and colonial surgeons. To everything accessible in French, German, and British works, he has added that contained in Italian, Swedish, American (U. S.), Swiss, and Danish literature. The last becomes particularly interesting, as it embodies the recent researches of M. Schleisner, who was charged officially to inquire into the sanitary condition of Iceland. The author has thus recently made an effort to accomplish the task of giving a résumé of all the facts which science now possesses, and has produced a work which is almost encyclopedic in its character, discussing with more or less fulness everything which he thought could influence results in such researches. It will be no easy matter, therefore, within the scope of a limited review, to present a complete analysis of so comprehensive a work.

The author divides the work into two parts. The first treats of the Physics of the Globe, and of Medical Meteorology; and to this, the whole of the first volume and a few pages of the second are devoted. The other division considers "man in a geographical point of view," and occupies a rather greater space. Much that is in the first division may appear to have no other than a purely scientific interest; and M. Boudin in many cases does not attempt to show the way in which the

phenomena discussed affect the laws of health or disease, nor indeed to establish between them any positive connexion. But, where all is so complex and so much is obscure, he appears to have thought it wise to omit nothing which might in any way throw light upon such questions.

His first chapter he devotes to the Solar System; and he is led, from discussing the annual and diurnal movements of the earth, to a consideration of periodical changes in man, making out a striking parallelism with this double movement, and adducing numerous illustrations. "Sicut in anno continentur periodi ægritudinum, eodem modo, una die."

According to the statistics of Quetelet, Buck, Ranken, Casper, Guiette, and Virey, which he has drawn together, the maximum of births takes place between midnight and six o'clock in the morning, and the minimum between midday and six P.M.; while, from the statistics of the same author, the minimum of deaths takes place invariably between six P.M. and midnight. The maximum of deaths occurs less definitely at one period. The point of real value-the strong pointin these statistics, is the uniformity and steadiness of the results in the hands of different observers. But the whole number of observations is too small to permit the deduction of any trustworthy inference. The sum of all the observations of the period of the day at which births take place only amounts to 5841, and of deaths only to 5591. The influence of seasons, however, on the same occurrences, rests on a much wider basis. For instance, by combining the statistics of Lastri and Ferrario, he presents a document embracing 1,186,515 births, spread over four hundred years, from 1451 to 1845. The analysis of this shows:

"1. That the months of April, May, and June-which were, towards the middle of the fifteenth century, the most fruitful, are still in our period the richest in conceptions; 2nd. That since the end of the fifteenth century the month of September has not ceased to be one of the months having the lowest share of conceptions; and 3rd. That the proportion of births of the one sex to the other has never varied during the course of four centuries."

With regard to the first two of these conclusions, he shows that they hold good over long periods for other towns in Italy; the minima, however, more constantly than the maxima. France appeared first to present an exception to this rule, but by applying certain corrections, which he thinks required and just, M. Boudin elicits from them also substantially the same inference.

The influence of the seasons on the distribution of deaths he holds to be very evident. In France, the maximum of mortality corresponds to the cold period of the year the spring months being highest of all. The same is true of Great Britain, of Denmark, and Schleswig, and of Europe generally, with the exception of such places as are devastated by marsh fever. Iceland, however, appears to be an exception, the maximum there occurring in July and August (1838 to 1844). If it be true, as M. Bunsen affirms, that Iceland is a malarious country, this seeming exception vanishes. There are several conditions which may perturb the influence of season on the rate of mortality, such as race, the special features of reigning diseases, &c. Thus, he tells us that in hot countries the highest mortality among Europeans corresponds to the hot months, while it is not always or usually so with the indigenous population. And he adduces in proof the statistics of Calcutta by Colonel Sykes. Of the other source of perturbation he draws his illustration from the influence of the plague in London. During its five visits to the metropolis (1593, 1625, 1603, 1636, and 1665), the greatest mortality fell in July, August, and September; and the same occurred during intervening normal years (1606 to 1610), which were remarkable as being free from plague; while now, at a period far removed from its direct or indirect influence, the maximum has become minimum, and vice versa.

Still further, on the subject of periodicity, he shows:

"1st. That the admissions of the insane into Charenton, from 1826 to 1832, followed a pro

gression parallel with the monthly increase of temperature, making the admissions in June and July fifty per cent. higher than in January; 2nd. That from 1835 to 1846 the number of suicides in France rose and fell with the rise and fall of the thermometer, so as to acquire in June and July a daily number double of that in January and December."

In the familiar phenomena of menstruation, the rut, hybernation, &c., we have striking instances of periodicity in animals; and there are many reasons for believing that it enters more extensively than we think into the laws of animal life, although it may be in a manner which is obscure. In vegetable life its operations are more general and more manifest, but perhaps not more real or important, than in animal. Every contribution, therefore, to the study of the question is of importance.

The second book treats of Medical Geology. After describing the different kinds of soil and their physical properties under a medical aspect, the author proceeds to show "that man is in more respects than one the mere expression of the soil on which he lives ;" and then shortly notices some of the ailments which are more directly connected with soil-such as ague, vesical calculus, goître, cretinism, and cholera.

Medical Hydrology is the title of the third book. After giving a full account of the physical and chemical properties of rain, spring, sea, and river waters, he details the researches of Chatin on the presence of iodine in fresh water, and its connexion with goître, which he seems to consider doubtful. Then follows a notice of the composition and other properties of mineral waters. Marshes, drainage, and water considered as a source of disease, terminate this book, and introduce us to a similar analysis of the atmosphere, to which three books are devoted. This is, in fact, a short treatise on medical meteorology. After an account of the physical and chemical properties of the atmosphere, and the phenomena of respiration, he is led to ask, "Whether carbonic acid possesses in itself a toxic action, or simply a negative one, due to the absence of atmospheric air." It appears that Orfila, Seguin, D'Arcat, and some others, accord to it a positively deleterious action; while Bichart, Nysten, Malgaigne, Berard, and perhaps Regnault, pronounce for the negative. The last observer, he tells us, has kept animals for several hours in air containing seven per cent. of carbonic acid; and he adds, that in order to kill a dog the air must contain thirty to forty per cent. But "it is said," he adds, "that three to four per cent. would suffice under the influence of combustion, in conse quence of the presence of the oxide of carbon, which, in the proportion of one per cent., destroys life." The subject of winds he discusses briefly; although he admits that, in a medical point of view, they play an important part, "sometimes in dissipating miasmata, sometimes in serving as a vehicle for them." On the last of these points, he says that science as yet wants well-observed facts. But winds do more than this. They are in a great measure the controllers of temperature and humidity, and the promoters of evaporation; and they possess individual unexplained peculiarities which affect both vegetable and animal life.

On the influence of diminished and increased atmospheric pressure, M. Boudin has brought together the different experiences of those who have ascended to great elevations on mountains, or in balloons, and of those who have subjected themselves to the reverse condition in diving-bells, mines, &c. From these it would appear that man can tolerate both states with less disturbance or injury than is generally supposed. Sudden transitions are felt, and have palpable and important influences; but they pass away or subside, so that at any rate discomfort is not felt. There is, however, in all probability, a permanent influence, the nature of which observation has not yet indicated.

Hygrometric phenomena are also briefly discussed-more briefly, perhaps, than they merit. Although wet and dry bulbs are in the hands of almost every observer, there is a poverty of materials on this subject. Whether it is the fault of the instrument, or of the troublesome and unsatisfactory character of the deductions and corrections to be made, this is certain-that there is a tendency not to give