general, he calls those trachea arteries, which we have distinguished by the name of pulmonary trachea. The arterial trachea of Lyonnet are the same as ours, and, in fact, no others exist in caterpillars. It may be proper to observe, that the two orders of tracheæ do not always exist; but the arterial are never wanting. Perhaps in the species in which we see only arterial tracheæ, the parts require a speedy impression from the air.

(To be continued.)

ARTICLE XI.

ANALYSES OF BOOKS.

I. Researches into the Physical History of Man. By James Cowles Pritchard, M. D. F. L. S. of Trinity College, Oxford; Fellow of the Wernerian Natural History Society of Edinburgh, and of the Medical Society of London; and extraordinary Member of the Royal Medical Society of Edinburgh. London, J. and A. Arch, IS13.

The physical history of man presents a field not less interesting than unexplored, yet Dr. Pritchard is the first who has exhibited it in a connected shape. By assembling together the most important facts he has been enabled to deduce general conclusions of considerable moment, some of which are so very remarkable as to excite something more than common surprise. The naturalists of all times have overlooked, whimsically enough, the history of our own species, and have devoted the whole of their attention to inferior animals. Yet in the course of their researches they have developed certain general principles, which may be applied to all parts of animated nature. The particular application of these principles to the human race appears to have been first made by Dr. Pritchard, although the subject has occasionally and casually engaged the attention of speculative philosophers, from the days of Aristotle to those of M. de Buffon. As it might naturally be expected, a thousand crude conjectures have supplied the place of accurate observations and reasonings. It it needless to repeat them here; it may suffice that, in general, the ancients considered the human race to be of one species, and ascribed every variation in point of form and colour to the effects of climate, the particular examples of which are abundantly ludicrous. The same opinion, variously modified, has been maintained by many moderns; but with most remarkable eloquence by Count de Buffon, in his Histoire Naturelle. This last named naturalist, however, did not possess a store of facts to resolve the difficulties that press on his peculiar modification of this hypothesis. Lord Kames stands at the head of another set of philosophers who maintain that mankind have sprung from various stocks, and that each particular race is especially adapted by Providence to the region in which they exist.

Dr. Prichard, without pledging himself to any opinion, investigates in the first place the criteria by which species are to be distinguished, and after examining those already offered, particularly that of John Hunter, who considered the sterility or fruitfulness of a hybrid the proof of difference or identity of species of the parents, he endeavours to lay down a general rule, derived from analogy, which, although imperfect, yields more satisfaction to the inquirer, than any solitary assumption can do. It has, too, the sanction of two of the most eminent naturalists of the present day. The rule which Dr. Pritchard lays down is, that after having observed a number of the changes produced in living bodies by adventitious causes, when any particular deviation is found frequently to recur, all parallel diversities may be ascribed to analogous causes, although the relations between these latter causes and their effects should not be so distinctly traced as in other more ordinary events. According to this rule, all the remarkable varieties of mankind, when compared with those of the inferior animals, particularly when domestication has displayed its effects, fall within the limits of one species; and Dr. P. makes the inference, that as the strictest analogy exists between the changes which almost the whole of the inferior tribes have a tendency to assume under known circumstances, and those diversities existing among men, it is consistent with the strictest rules of philosophizing to infer, that these changes originate in the' principle of natural deviation, and furnishing no specific distinction."

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The next branch of the inquiry is how far men are to be considered as having all proceeded from one common stock. This question has been treated of by several writers purely on historical evidence; Dr. Pritchard, however, without disregarding the powerful arguments afforded by the historical researches of Sir W. Jones, Bailey, and others, still proceeds on analogy, and endeavours to solve the general problem as it regards all organized tribes, but more particularly animals. With much acuteness he has examined. the distribution of animals, more especially in those vast regions of the southern hemisphere, so little known until the important discoveries of Cook, Bougainville, Wallis, Flinders, and others, had removed the veil which was spread over Nature; and concludes by inferring, "that every existing species may be traced with probability to a certain point which appears to have been its original abode; and that few or no species have been found in countries separated from their primary seats by barriers which their locomotive powers and peculiar structure do not enable them to surmount." This inference, if true in general, includes the particular case of the human species.

Having thus established the criteria of species, and rendered it probable that species were originally confined to one point, it is necessary to determine as far as possible, what are the causes that produce the very extraordinary diversities which exist among mankind. The commonly maintained hypotheses of those who adopt

the opinion of the unity of species among men, that a change produced in the white European by heat and food becomes hereditary, is exceedingly inconsistent with notorious facts. Nor does it receive any additional weight from its antiquity; that only affords an additional proof of the facility with which even absurdity may be propagated under the sanction of illustrious names. Dr. Pritchard shows that the previous opinions are irreconcileable with fact, and supposes that certain causes exist, which, acting on the parents, "influence them to produce an offspring endowed with certain peculiar characters, which characters, according to the law of Nature, become hereditary, and thus modify the race." In order to develope those causes, Dr. P. shows that, although climates produce very remarkable variations in individuals, both in the animal and vegetable kingdoms, yet the only permanent effects seem to be derived from cultivation and domestication. Of these effects there are ample and apposite proofs in our cultivated fruits, and among domestic animals. The original stocks remain unaltered, while the most extraordinary changes are brought about by culture. Dr. P. institutes a parallel between the culture of plants, the domestication of animals, and the civilization of man; and, while he allows that some connate varieties may be produced by climate, he insists that the condition of man in social life influences more extensively the physical structure than any variety of latitude or local temperature: and concludes by ascribing those remarkable diversities among mankind, not to any moral cause, but to physical causes connected with a particular mode of life. Of this, several interesting illustrations might be cited, in addition to those given by Dr. Pritchard.

Having established the probability of these opinions, he proceeds to determine whether the original race were white or black; and having shewn that black, or at least a very dark brown, in all the inferior tribes, is the primitive colour; and that the same complexion prevails among all savages, and a gradual change towards white occurs through successive races of semi-barbarians to perfect civilization, he infers that the prototype of the human race was a Negro. However satisfactorily this conclusion may be drawn, it is necessary to afford some proof, and accordingly the author adduces numerous illustrations calculated to give considerable force to his argument. He urges with much force the singular varieties in form and complexion among the widely scattered nations of the Pacific Ocean; who exhibit almost every variety, from the savage Papuan to the highly refined European. He proves, by similarity of language, of religious rites, and other points of coincidence, their common origin; and then applies the results obviously obtained from these individuals to the whole of the human race.

The outline then of these Researches into the physical history of man, is, that as uniform diversities are produced by certain known causes; so, all similar or analogous diversities should be ascribed to analogous causes. That as an analogy does actually

exist between certain phenomena among mankind, and those which commonly occur among the tribes, they must be all ascribed to one uniform principle of Nature. That every individual species may be traced to one original birth-place, and consequently, that the human species have had an original abode. That the cause which produces the diversities among mankind is civilization, which does not produce any effect on the parent which is hereditary; but, by acting on the parent physically, influences the production of certain offspring. And finally, that the change in form and complexion has been from black to white; and that the primitive race of men were negroes. After these conclusions, the remainder of the volume is chiefly devoted to historical researches in corroboration of the last startling inference. From these inquiries it appears, that the most ancient nations of whom we have any record were negroes, that they have gradually lost their characters, and that many, or most of the now existing nations, though widely differing in form and complexion, may be traced to them.

The Hindoos and Egyptians are certainly the oldest nations of antiquity. The correspondence between them is very remarkable, and the importance of the resemblance increases as we find it increase in proportion to the antiquity of the period to which we refer. In morals, in politics, and endless superstition, the resemblance is so unbounded, as to leave no doubt of an identity of origin. The pretensions of the Babylonians, who alone rival them in antiquity, will not admit of scrutiny. It will be worth while to ascertain the physical and mutual connexion of these early races, as by doing so, some light would probably be thrown on the history of the species in general. These nations appear originally to have been absolute negroes.

It is to be hoped that Dr. Pritchard will pursue this very import ant subject through all the forms of which it is susceptible, and to which he appears so fully competent to give interest.

II. Traité des Poisons tirées des Regnes Mineral, Vegetal, et Animal, &c. A Treatise on the Poisons of the Mineral, Vegetable, and Animal Kingdoms, or a general Toxology considered as related to Physiology, Pathology, and Medical Jurisprudence. By M. P. Orfila, Pensionary Naturalist of Spain, Doctor in Medicine of the Faculty of Paris, Professor of Chemistry and of Natural Philosophy. Vol. I. Paris, 1814.

This work, if we are to form a judgment from the part of it which is already published, promises to be very complete. The author is a practical chemist, as well as a physician, and he has laid it down as a rule to give an account of no poison without an exact description of its properties, and without ascertaining by experiment the effects which it produces on animals. If we were disposed to find fault we should blame the author for the too great number of parts into which he has subdivided each article. This

has occasioned some repetition, and given rather a stiff appearance to the work. But when the novelty of many of the subjects treated of is considered, and the numerous mistakes respecting them still taught in the most recent books on medical jurisprudence, it was better to err on the side of minuteness and repetition than on that of omission.

The

M. Orfila divides poisons into six classes; namely, corrosive, astringent, acrid, stupifying, narcotico-acrid, and septic. present volume, published in two parts, includes the first two of these classes.

The corrosive poisons consist of preparations of the following substances: mercury, arsenic, antimony, copper, tin, zinc, silver, gold, bismuth. It includes likewise the following substances; sulphuric acid, nitric acid, muriatic acid, phosphoric acid, fluoric acid, oxalic acid, tartaric acid; the caustic alkalies, barytes, lime; phosphorus; cantharides. The astringent poisons are confined to preparations of lead.

The principal poisonous preparation of mercury is corrosive sublimate, or deuchloride of mercury. The chemical properties of this salt are described at great length. It may be sufficient here to say, that it is a white, heavy substance, having an acrid taste, and soluble in about 11 times its weight of water. When heated it sublimes in a white smoke, which excites coughing; but has not an alliacious smell. If a plate of clean copper be exposed to this smoke it becomes tarnished, and when rubbed assumes a white colour. The solution of corrosive sublimate is precipitated brick red by an alkaline carbonate; yellow by a caustic fixed alkali and lime-water; white by ammonia; white by prussiate of potash; black by a hydrosulphuret; white by albumen. Corrosive sublimate, when swallowed in a considerable dose, (as 30 grains) acts with great violence, occasioning evacuations both upwards and downwards, and death very speedily ensues. M. Orfila has ascertained that white of egg, dissolved in water, and administered in considerable quantity, and as speedily as possible, constitutes the best antidote to this poison.

All the preparations of arsenic are violent poisons; but the most common state in which it is administered is that of arsenious acid, or white oxide of arsenic. Its properties, and the fatal effects which it produces when taken internally, are so well known, that it would be superfluous to describe them here. When arsenic is swallowed in a state of solution, sulphureted hydrogen taken soon after is an efficacious antidote. But this poison is usually administered in a solid state, and in that case the antidote is totally inefficacious. The proper treatment is to endeavour to get the poison out of the stomach as speedily as possible, by vomiting. Great quantities of hot water, having some sugar or mucilaginous matter dissolved in it, should be swallowed, and vomiting excited, if it does not take place spontaneously, by introducing the finger, or a