Chapter I: HAVE endeavored, in the preceding part of my work, to explain and (16)

Sometimes, however, the stratum of cloud from which the thunder proceeds sinks to a distance of 5000, or, indeed, only 3000 feet above the plain.

According to Arago's investigations -- the most comprehensive that we possess on this difficult branch of meteorology -- the evolution of light (lightning) is of three kinds -- zigzag, and sharply defined at the edges; in sheets of light, illuminating a whole cloud, which seems to open and refeal the light within it; and in the form of fire-balls.*

[footnote] *Arago, op. cit., p. 249-266. (See also, p. 268-279.)

The duration of the two first kinds scarcely continues the thousandth part of a second; but the globular lightning moves much more slowly remaining visible for several seconds. Occasionally (as is proved by the recent observations, which have confirmed the description given by Nicholson and Beccaria of this phenomenon), isolated clouds, standing high above the horizon, continue uninterruptedly for some time to emit a luminous radiance from their interior and from their margins, although there is no thunder to be heard, and no indication of a storm; in some cases even hail-stones, drops of rain, and flakes of snow have been seen to fall in a luminous condition, when the phenomenon was not preceded by thunder. In the geographical distribution of storms, the Peruvian coast, which is not visited by thunder or lightning, presents the most striking contrast to the rest of the tropical zone, in which, at certain seasons of the year, thunder-storms occur almost daily, about four or five hours after the sun has reached the meridian. According to the abundant evidence collected by Arago* from the testiimony of navigators (Scoresby, Parry, Ross, and Franklin), there can be no doubt that, in general, electric explosions are extremely rare in high northern regions (between 70 degrees and 75 degrees latitude).

[footnote] *Arago, op. cit., p. 388-391. The learned academician Von Baer, who has done so much for the meteorology of Northern Asia, has not taken into consideration the extreme rarity of storms in Iceland and Greenland; he has only remarked ('Bulletin de l'Academie de St. Petersbourg', 1839, Mai) that in Nova Zembla and Spitzbergen it is sometimes heard to thunder.

'The meteorological portion' of the descriptive history of nature which we are now concluding shows that the processes of the absorption of light, the liberation of heat, and the variations in the elastic and electric tension, and in the hygrometric condition of the vast aerial ocean, are all so intimately connected together, that each individual meteorological process is modified by the action of all the others. The complicated p 338 nature of these disturbing causes (which involuntarily remind us of those which the near and especially the smallest cosmical bodies, the satellites, comets, and shooting stars, are subjected to in their course) increases the difficulty of giving a full explanation of these involved meteorological phenomena, and likewise limits, or wholly precludes, the possibility of that predetermination of atmospheric changes which would be so important for horticulture, agriculture, and navigation, no less than for the comfort and enjoyment of life. Those who place the value of meteorology in this problematic species of prediction rather than in the knowledge of the phenomena themselves, are firmly convinced that this branch of science, on account of which so many expeditions to distant mountainous regions have been undertaken, has not made any very considerable progress for centuries past. The confidence which they refuse to the physicist they yield to changes of the moon, and to certain days marked in the calendar by the superstition of a by-gone age.

"Great local deviations from the distribution of the mean temperature are of rare occurrence, the variations being in general uniformly distributed over extensive tracts of land. the deviation, after attaining its maximum at a certain point, gradually decreases to its limits; when these are passed, however, decided deviations are observed in the 'opposite direction'. Similar relations of weather extend more frequently from south to north than from west to east. At the close of the year 1829 (when I had just completed my Siberian journey), the maximum of cold was at Berlin, while North America enjoyed an unusually high temperature. It is an entirely arbitrary assumption to believe that a hot summer succeeds a severe winter, and that a cool summer is preceded by a mild winter." Opposite relations of weather in contiguous countries, or in two corn-growing continents, give rise to a beneficient equalization in the prices of the products of the vine, and of agricultural and horticultural cultivation. It has been justy remarked, that it is the barometer alone which indicates to us the changes that occur in the pressure of the air throughout all the aerial strata from the place of observation to the extremest confines of the atmosphere, while* the thermometer and psychrometer only acquaint us with all the variations occurring in the local heat and moisture of the lower strata of p 339 air in contact with the ground.

[footnote] *Kämtz, in Schumacher's 'Jahrbuch fur' 1838, s. 285. Regarding the opposite distribution of heat in the east and the west of Europe and North America, see Dove, 'Repertorium der Physik', bd. iii., s. 392-395.

The simultaneous thermic and hygrometric modifications of the upper regions of the air can only be learned (when direct observations on mountain stations or aerostatic ascents are impracticable) from hypothetical combinations, by making the barometer serve both as a thermometer and an hygrometer. Important changes of weather are not owing to merely local causes, situated at the place of observation, but are the consequence of a disturbance in the equilibrium of the aerial currents at a great distance from the surface of the Earth, in the higher strata of the atmosphere, bringing cold or warm, dry or moist air, rendering the sky cloudy or serene, and converting the accumulated masses of clouds into light feathery 'cirri'. As, therefore, the inaccessibility of the phenomenon is added to the manifold nature and complication of the disturbances, it has always appeared to me that meteorology must first seek its foundation and progress in the torrid zone, where the variations of the atmospheric pressure, the course of hydro-meteors, and the phenomena of electric explosion, are all of periodic occurrence.

As we have now passed in review the whole sphere of inorganic terrestrial life, and have briefly considered our planet with reference to its form, its internal heat, its electro-magnetic tension, its phenomena of polar light, the volcanic reaction of its interior on its variously composed solid crust, and, lastly, the phenomena of its two-fold envelopes -- the aerial and liquid ocean -- we might, in accordance with the older method of treating physical geography, consider that we had completed our descriptive history of the globe. But the nobler aim I have proposed to myself, of raising the contemplation of nature to a more elevated point of view, would be defeated, and this delineation of nature would appear to lose its most attractive charm, if it did not also include the sphere of organic life in the many stages of its typical development. The idea of vitality is so intimatey associated with the idea of the existence of the active, ever-blending natural forces which animate the terrestrial sphere, that the creation of plants and animals is ascribed in the most ancient mythical representations of many nations to these forces, while the condition of the surface of our planet, before it was animated by vital forms, is regarded as coeval with the epoch of a chaotic conflict of the struggling elements. But the empirical domain of objective contemplation, and the delineation of our planet in its present condition, do not include a consideration p 340 of the mysterious and insoluble problems of origin and existence.

A cosmical history of the universe, resting upon facts as its basis, has, from the nature and limitations of its sphere, necessarily no connection with the obscure domain embraced by a 'history of organisms',* if we understand the word 'history' in its broadest sense.

[footnote] *The 'history of plants', which Endlicher and Unger have described in a most masterly manner ('Grundzuge der Botanik', 1843, s. 449-468), I myself separated from the 'geography of plants' half a century ago. In the aphorisms appended to my 'Subterranean Flora', the following passage occurs: "Geognosia naturam animantem et inanimam vel, ut vocabulo minus apto, ex antiquitate saltem haud petito, utar, corpora vitur capita: Geographia oryctologica quam simpliciter Geognosiam vel Geologiam dicunt, virque acutissimus Wernerus egregie digessit; Geographia zoologica, cujus doctrinae fundamenta Zimmermannus et Treviranus jecerunt; et Geographic plantarum quam aequales nostri diu intactam reliquerunt. Geographia plantarum vincula et cognationem tradit, quibus omnia vegetabilia inter se connexa sint, terraetractur quos teneant, in aerem atmosphaericum quae sit eorum vis ostendit, saxa atque rupes quibus potissimum algarum primordiis radicibusque destruantur docet, et quo pacto in telluris superficie humus nascatur, commemorat. Est itaque quod differat inter Geognosiam et Physiographiam, 'historia naturalis' perperam nuncupatam quum Zoognosia, Phytognosia, et Oryctognosia, quae quidem omnes in naturae investigatione versantur, non nisi singulorum animalium, plantarum, rerum metallicarum vel (venia sit verbo) fossilium formas, anatomen, vires scrutautur. Historia Telluris, Geognosiae magis quam Physiographiae affinis, nemini adhuc tenata, plantarum animaliumque genera orbem inhabitantia primaevum, migrationes eorum compluriumque interitum, ortum quem montes, valles, saxorum strata et vemae metalliferae ducunt, aerem, mutatis temporum vicibus, modo purum, modo vitiatum, terrae superficiem humo plantisque paulatim obtectam, fluminum inundantium impetu denuo nudatam, iterumque siccatam et gramine vestitam commemorat. Igitur Historia zoolopgica, Historia plantarum et Historia oryctologica, quae non nisi pristinum orbis terrae statum indicant, a Geognosia probe distinguendae." -- Humboldt, 'Flora Friburgensis Subterranea, cui accedunt Aphorismi ex Physiologia Chemica Plantarum', 1793, p. ix.-x. Respecting the "spontaneous motion." which is referred to in a subsequent part of the text, see the remarkable passage in Aristotle, 'De Coelo,' ii., 2, p. 284, Bekker, where the distinction between animate and inanimate bodies is made to depend on the internal or external position of the seat of the determining motion. "No movement," says the Stagirite, "proceeds from the vegetable spirit, because plants are buried in a still sleep, from which nothing can arouse them" (Aristotle, 'De Generat. Animal.', v. i., p. 778, Bekker); and again, "because plants have no desires which incite them to spontaneous motion." (Arist., 'De Somno et Vigil'., cap. i., p. 455, Bekker.)

It must, however, be remembered, that the inorganic crust of the Earth contains within it the same elements that enter into the structure of animal and vegetable organs. A physical cosmography would therefore be incomplete p 341 if it were to omit a consideration of these forces, and of the substances which enter into solid and fluid combinations in organic tissues, under conditiions which, from our ignorance of their actual nature, we designate by the vague term of 'vital forces', and group into various systems in accordance with more or less perfectly conceived analogies. The natural tendency of the human mind involuntarily prompts us to follow the physical phenomena of the Earth, through all their varied series, until we reach the final stage of the morphological evolution of vegetable forms, and the self-determining powers of motion in animal organisms. And it is by these links that 'the geography of organic beings -- of plants and animals' -- is connected with the delineation of the inorganic phenomena of our terrestrial globe.

Without entering on the difficult question of 'spontaneous motion', or, in other words, on the difference between vegetable and animal life, we would remark, that if nature had endowed us with microscopic powers of vision, and the integuments of plants had been rendered perfectly transparent to our eyes, the vegetable world would present a very different aspect from the apparent immobility and repose in which it is now manifested to our senses. The interior portion of the cellular structure of their organs is incessantly animated by the most varied currents, either rotating, ascending and descending, remifying, and ever changing their direction, as manifested in the motion of the granular mucus of marine plants (Naiades, Characeae, Hydrocharidae), and in the hairs of phanerogamic land plants; in the molecular motion first discovered by the illustrious botanist Robert Brown, and which may be traced in the ultimate portions of every molecule of matter, even when separated from the organ; in the gyratory currents of the globules of cambium ('cyclosis') circulating in their peculiar vessels; and, finally, in the singularly articulated self-unrolling filamentous vessels in the antheridia of the chara, and in the reproductive organs of liverworts and algae, in the structural conditions of which Meyen, unhappily too early lost to science, believed that he recognized an analogy with the spermatozoa of the animal kingdom.*

[footnote] *["In certain parts, probably, of all plants, are found peculiar spiral filaments, having a striking resemblance to the spermatozoa of animals. They have been long known in the organs called the antheridia of mosses, Hepaticcae, and Characeae, and have more recently been discovered in peculiar cells on the germinal frond of ferns, and on the very young leaves of the buds of Phanerogamia. They are found in peculiar cells, and when these are placed in water they are torn by the filament, which commences an active spiral motion. The signification of these organs is at present quite unknown; they appear, from the researches of Nägeli, to resemble the cell mucilage, or proto-plasma, in composition, and are developed from it. Schleiden regards them as mere mucilaginous deposits, similar to those connected with the circulation in cells, and he contends that the movement of these bodies in water is analogous to the molecular motion of small particles of organic and inorganic substances, and depends on mechanical causes." -- 'Outlines of Structural and Physiological Botany', by A. Henfrey, F.L.S., etc., 1846, p. 23.] -- Tr.

If to these p 342 manifold currents and gyratory movements we add the phenomena of endosmosis, nutrition, and growth, we shall have some idea of those forces which are ever active amid the apparent repose of vegetable life.

Since I attempted in a former work, 'Ansichten der Natur' (Views of Nature), to delineate the universal diffusion of life over the whole surface of the Earth, in the distribution of organic forms, both with respect to elevation and depth, our knowledge of this branch of science has been most remarkably increased by Ehrenberg's brilliant discovery "on microscopic life in the ocean, and in the ice of the polar regions" -- a discovery based, not on deductive conclusions, but on direct observation. The sphere of vitality, we might almost say, the horizon of life, has been expanded before our eyes. "Not only in the polar regions is there an uninterrupted development of active microscopic life, where larger animals can no longer exist, but we find that the microscopic animals collected in the Antarctic expedition of Captain James Ross exhibit a remarkable abundance of unknown and often most beautiful forms. Even in the residuum obtained from the melted ice, swimming about in round fragments in the latitude of 70 degrees 10', there were found upward of fifty species of silicious-shelled Polygastria and Coscinodiscae with their green ovaries, and therefore living and able to resist the extreme severity of the cold. In the Gulf of Erebus, sixty-eight silicious-shelled Polygastria and Phytolitharia, and only one calcareous-shelled Polythalamia, were brought up by lead sunk to a depth of from 1242 to 1620 feet."

The greater number of the oceanic microscopic forms hitherto discovered have been silicious-shelled, although the analysis of sea water does not yield silica as the main constituent, and it can only be imagined to exist in it in a state of suspension. It is not only at particular points in inland seas, or in the vicinity of the land, that the ocean is densely inhabited by living atoms, invisible to the naked eye, but samples of p 343 water taken up by Schayer on his return from Van Diemen's Land (south of the Cape of Good Hope, in 57 degrees latitude, and under the tropics in the Atlantic) show that the ocean in its ordinary condition, without any apparent discoloration, contains numerous microscopic moving organisms, which bear no resemblance to the swimming fragmentary silicious filaments of the genus Chaetoceros, similar to the Oscillatoriae so common in our fresh waters. Some few Polygastria, which have been found mixed with sand and excrements of penguins in Cockburn Island, appear to be spread over the whole earth, while others seem to be peculiar to the polar regions.*

[footnote] *See Ehrenberg's treatise 'Ueber das kleinste Leben im Ocean', read before the Academy of Science at Berlin on the 9th of May, 1844. [Dr. J. Hooker found Diatomaceae in countless numbers between the parallels of 70 degrees and 80 degrees south, where they gave a color to the sea, and also the icebergs floating in it. The death of these bodies in the South Arctic Ocean is producing a submarine deposit, consisting entirely of the silicious particles of which the skeletons of these vegetables are composed. This deposit exists on the shores of Victoria Land and at the base of the volcanic mountain Erebus. Dr. Hooker accounted for the fact that the skeletons of Diatomaceae had been found in the lava of volcanic mountains, by referring to these deposits at Mount Erebus, which lie in such a position as to render it quite possible that the skeletons of these vegetables should pass into the lower fissures of the mountain, and then passing into the stream of lava, be thrown out, unacted upon by the heat to which they have been exposed. See Dr. Hooker's Paper, read before the British Association at Oxford, July, 1847.] -- Tr.

We thus find from the most recent observations that animal life predominates amid the eternal night of the depths of ocean, while vegetable life, which is so dependent on the periodic action of the solar rays, is most prevalent on continents. The mass of vegetation on the Earth very far exceeds that of animal organisms; for what is the volume of all the large living Cetacea and Pachydermata when compared with the thickly-crosded colossal trunks of trees, of from eight to twelve feet in diameter, which fill the vast forests covering the tropical region of South America, between the Orinoco, the Amazon, and the Rio de Madeira? And although the character of different portions of the earth depends on the combination of external phenomena, as the outlines of mountains -- the physiognomy of plants and animals -- the azure of the sky -- the forms of the clouds -- and the transparency of the atmosphere -- it must still be admitted that the vegetable mantle with which the earth is decked constitutes the main feature of the picture. Animal forms are inferior in mass, and their powers of motion often withdraw them from our sight. The p 344 vegetable kingdom, on the contrary, acts upon our imagination by its continued presence and by the magnitude of its forms; for the size of a tree indicates its age, and here alone age is associated with the expression of a constantly renewed vigor.*

[footnote] *Humboldt, 'Ansichten der Natur' (2te Ausgabe, 1826), bd. ii. s. 21.

In the animal kingdom (and this knowledge is also the result of Ehrenberg's discoveries), the form which we term microscopic occupy the largest space, in consequence of their rapid propagation.*

[footnote] *On multiplication by spontaneous division of the mother-corpuscle and intercalation of new substance, see Ehrenberg 'Van den jetzt lebenden Thierarten der Kreidebildung', in the 'Abhandl. der Berliner Akad. der Wiss.', 1839, s. 94. The most powerful productive faculty in nature is that manifested in the Vorticellae. Estimations of the greatest possible development of masses will be found in Chrenberg's great work 'Die Infusionsthierchen als volkommne Organismen', 1838, s. xiii., xix., and 244. "The Milky Way of these organisms comprises the genera Monas, Vibrio, Bacterium, and Bodo." The universality of life is so profusely distributed throughout the whole of nature, that the smaller Infusoria live as parasites on the larger, and are themselves inhabited by others, s. 194, 211, and 512.

The minutest of the Infusoria, the Monadidae, have a diameter which does not exceed 1/3000th of a line, and yet these silicious-shelled organisms form in humid districts subterranean strata of many fathoms in depth.

The strong and beneficial influence exercised on the feelings of mankind by the consideration of the diffusion of life, throughout the realms of nature is common to every zone, but the impression thus produced is most powerful in the equatorial regions, in the land of palms, bamboos, and arborescent ferns, where the ground rises from the shore of seas rich in mollusca and corals to the limits of perpetual snow. The local distribution of plants embraces almost all heights and all depths. Organic forms not only descend into the interior of the earth, where the industry of the miner has laid open extensive excavations and sprung deep shafts, but I have also found snow-white stalactiitic columns encircled by the delicate web of an Usnea, in caves where meteoric water could alone penetrate through fissures. Podurellae penetrate into the icy crevices of the glaciers on Mount Rosa, the Grindelwald, and the Upper Aar; the Chionaea nivalis (formerly known as Protococcus), exist in the polar snow as well as in that of our high mountains. The redness assumed by the snow after lying on the ground for soome time was known to Aristotle, and was probably observed by him on the mountains of Macedonia.*

[footnote] *Aristot., 'Hist. Animal.', v. xix., p. 552, Bekk.

p 345 While, on the loftiest summits of the Alps, only Lecideae, Parmeliae, and Umbilicariae cast their colored but scanty covering over the rocks, exposed by the melted snow, beautiful phanerogamic plants, as the Culcitium rufescens, Sida pinchinchensis, and Saxifraga Boussingaulti, are still found to flourish in the tropical region of the chain of the Andes, at an elevation of more than 15,000 feet. Thermal springs contain small insects (Hydroporus thermalis), Gallionellae, Oscillatoria and Confervae, while their waters bathe the root-fibers of phanerogamic plants. As air and water are aniimated at different temperatures by the presence of vital organisms, so likewise is the interior of the different portions of animal bodies. Animalcules have been found in the blood of the frog and the salmon; according to Nordmann, the fluids in the eyes of fishes are often filled with a worm that lives by suction (Diplostomum), while in the gills of the bleak the same observer has discovered a remarkable double aniimalcule (Diplozoon paradoxum), having a cross-shaped form with two heads and two caudal extremities.

Although the existence of meteoric Infusoria is more than doubtful, it can not be denied that, in the same manner as the pollen of the flowers of the pine is observed every year to fall from the atmosphere, minute infusorial animalcules may likewise be retained for a time in the strata of the air, after having been passively borne up by currents of aqueous vapor.*

[footnote] *Ehrenberg, op. cit., s. xiv., p. 122 and 403. The rapid multiplication of microscopic organisms is, in the case of some (as, for instance, in wheat-eels, wheel-animals, and water-bears or tardigrade animalcules), accompanied by a remarkable tenacity of life. They have been seen to come to life from a state of apparent death after being dried for twenty-eight days in a vacuum with chloride of line and sulphuric acid, and after being exposed to a heat of 248 degrees. See the beautiful experiments of Doyere, in 'Mem. sur les Tardigrades et sur leur propriete de revenir a la vie', 1842, p. 119, 129, 131, 133. Compare, also, Ehrenberg, s. 492-496, on the revival of animalcules that had been dried during a space of many years.

This circumstance merits serious attention in reconsidering the old discussion respecting 'spontaneous generation',* and the p 346 more so, as Ehrenberg, as I have already remarked, has discovered that the nebulous dust or sand which mariners often encounter in the vicinity of the Cape Verd Islands, and even at a distance of 380 geographical miles from the African shore, contains the remains of eighteen species of silicious-shelled polygastric animalcules.

[footnote] *On the supposed "primitive transformation" of organized or unorganized matter into plants and animals, see Ehrenberg, in Poggendorf's 'Annalen der Physik', bd. xxiv., s. 1-48, and also his 'Infusionsthierchen', s. 121, 525, and Joh. Muller, 'Physiologie des Menschen' (4te Aufl., 1844), bd. i., s. 8-17. It appears to me worthy of notice that one of the early fathers of the Church, St. Augustine, in treating of the question how islands may have been covered with new animals and plants after the flood, shows himself in no way disinclined to adope the view of the so-called "spontaneous generation" ('generatio aequivoca, spontanea aut primaria'). "If," says he, "animals have not been brought to remote islands by angels, or perhaps by inhabitants of continents addicted to the chase, they must have been spontaneously produced upon the earth; although here the question certainly arises, to what purpose, then, were animals of all kinds assembled in the ark?" "Si e terra exort" sunt (bestiae) secundum originem primam, quando dixit Deus" 'Producat terra animam vivam!' multo clarius apparet, non tam reparandorum animalium causa, quam figurandarum variarum gentium (?) propter ecclesiae sacramentumin arca fuisse omnia genera, si in insulis quo transire non possent, multa animalia terra produxit." Augustinus, 'De Civitate Dei', lib. xvi., cap. 7: 'Opera, ed. Monach. Ordinis S. Benedicti', t. vii., Venet., 1732, p. 422. Two centuries before the tiime of the Bishop of Hippo, we find, by extracts from Trogus Pompeius, that the 'generatio primaria' was brought forward in connection with the earliest drying up of the ancient world, and of the high table-land of Asia, precisely in the same manner as the terraces of Paradise, in the theory of the great Linnaeus, and in the visionary hypotheses entertained in the eighteenth century regarding the fabled Atlantis: "Quod si omnes quondam terrae submersae profundo fuerunt, profecto editissilimam quamque partem decurrentibus aquis primum detectam; humillimo autem solo eandem aquam diutissime immoratam, et quanto prior quaeque pars terrarum siccata sit, tanto prius animalia generare coepisse. Porro Scythiam adeo editiorem omnibus terris esse ut cuncta flumina ibi nata in Maeotium, tum deinde in Ponticum et Aegyptium mare decurrant." -- Justinus, lib. ii., cap. 1. The erroneous supposition that the land of Scythia is an elevated table-land, is so ancient that we meet with it most clearly expressed in Hippocrates, 'De Aere et Aquis', cap. 6, 96, Coray. "Scythia," says he, "coonsists of high and naked plains, which, without being crowned with mountains, ascend higher and higher toward the north."

Vital organisms, whose relations in space are comprised under the head of the geography of plants and animals, may be considered either according to the difference and relative numbers of the types (their arrangement into genera and species), or according to the number of individuals of each species on a given area. In the mode of life of plants as in that of animals, an important difference is noticed; they either exist in an isolated state, or live in a social condition. Those species of plants which I have termed 'social'* uniformly cover vast extents of land.

[footnote] *Humboldt, 'Aphorismi ex Physiologia Chemica Plantarum', in the 'Flora Fribergensis Subterranea', 1793, p. 178.

Among these we may reckon many of the marine Algae -- Cladoniae and mosses, which extend over the desert steppes of Northern Asia -- grasses, and cacti growing p 347 together like the pipes of an organ -- Avicennim and mangroves in the tropics -- and forests of Coniferae and of birches in the plains of the Baltic and in Siberia. This mode of geographical distribution determines, together with the individual form of the vegetable world, the size and type of leaves and flowers, in fact, the principal physiognomy of the district,* its characteracter being but little, if at all, influenced by the ever-moving forms of animal life, which, by their beauty and diversity, so powerfully affect the feelings of man, whether by exciting the sensations of admiration or horror.

[footnote] *On the physiognomy of plants, see Humboldt, 'Anischten der Natur', bd. ii., s. 1-125.

Agricultural nations increase artificially the predominance of social plants, and thus augment, in many parts of the temperate and northern zones, the natural aspect of uniformity; and while their labors tend to the extirpation of some wild plants, they likewise lead to the cultivation of others, which follow the colonist in his most distant migration. The luxuriant zone of the tropics offers the strongest resistance to these changes in the natural distribution of vegetable forms.

Observers who in short periods of time have passed over vast tracts of land, and ascended lofty mountains, in which climates were ranged, as it were in strata one above another, must have been early impressed by the regularity with which vegetable forms are distributed. The results yielded by their observations furnished the rough materials for a science, to which no name had as yet been given. The same zones of regions of vegetation which, in the sixteenth century, Cardinal Bembo, when a youth,*described on the declivity of Aetna, were observed on Mount Ararat by Tournefort.

[footnote] *Aetna Dialogus.' 'Opuscula', Basil., 1556, p. 53, 54. A very beautiful geography of the plants of Mount AEtna has recently been published by Philippi. See 'Linnaea', 1832, s. 733.

He ingeniously compared the Alpine flora with the flora of plains situated in different latitudes, and was the first to observe the influence exercised in mountainous regions, on the distribution of plants by the elevation of the ground above the level of the sea, and by the distance from the poles in flat countries. Menzel, in an inedited work on the flora of Japan, accidentally made use of the term 'geography of plants'; and the same expression occurs in the fanciful but graceful work of Bernardin de St. Pierre, 'Etudes de la Nature'. A scientific treatment of the subject began, however, only when the geography of plants was intimately associated with the study of the distribution p 348 of heat over the surface of the earth, and when the arrangement of vegetable forms in natural families admitted of a numerical estimate being made of the different forms which increase of decrease as we recede from the equator toward the poles, and of the relations in which, in diffrent parts of the earth, each family stood with reference to the whole mass of phanerogamic indigenous plants of the same region. I consider it a happy circumstance that, at the time during which I devoted my attention almost exclusively to botanical pursuits, I was led by the aspect of the grand and strongly characterized features of tropical scenery to direct my investigations toward these subjects.

The study of the geographical distribution of animals, regarding which Buffon first advanced general, and, in most instances, very correct views, has been considerably aided in its advance by the progress made in modern times in the geography of plants. The curves of the isothermal lines, and more especially those of the isochimenal lines, correspond with the limits which are seldom passed by certain species of plants, and of animals which do not wander far from their fixed habitation either with respect to elevation or latitude.*

[footnote] *[The following valuable remarks by Professor Forbes, on the correspondence existing between the distribution of existing faunas and floras of the British Islands, and the geological changes that have affected their area, will be read with much interest; they have been copied, by the author's permission, from the 'Survey Report', p. 16: "If the view I have put forward respecting the origin of the flora of the British mountains be true -- and every geological and botanical probability, so far as the are is concerned, favors it -- then must we endeavour to find some more plausible cause than any yet shown for the presence of numerous species of plants, and of some animals, on the higher parts of Alpine ranges in Europe and Asia, specifically identical with animals and plants indigenous in the regions very far north, and not found in the intermediate lowlands. Tournefort first remarked and Humboldt, the great organizer of the science of natural history geography, demonstrated, that zones of elevation on mountains correspond to parallels of latitude, the higher with the more northern or southern, as the case might be. It is well known that this correspondence is recognized in the general 'facies' of the flora and fauna, dependent on generic identities. But when announcing and illustrating the law that climatal zones of animal and vegetable life are mutually repeated or represented by elevation and latitude, naturalists have not hitherto sufficiently (if at all) distinguished between the evidence of that law, as exhibited by 'representative species' and by 'identical'. In reality, the former essentially depend on the law, the latter being an 'accident' not necessarily dependent upon it, and which has hitherto not been accounted for. In the case of the Alpine flora of Britain, the evidence of the activity of the law, and the influence of the accident, are inseparable, the law being maintained by a transported flora, for the transmission of which I have shown we can not account by an appeal to unquestionable geological events. In the case of the Alps and Carpathians, and some other mountain ranges, we find the law maintained partly by a representative flora, special in its region, i.e., by specific centers of their own, and partly by an assemblage more or less limited in the several ranges of identical species, these latter in several cases so numerous that ordinary modes of transportation now in action can no more account for their presence than they can for the presence of a Norwegian flora on the British mountains. Now I am prepared to maintain that the same means which introduced a sub-Arctic (now mmountain) flora into Britain, acting at the same epoch, originated the identity, as far as it goes, of the Alpine floras of middle Europe and Central Asia; for, now that we know the vast area swept by the glacial sea, including almost the whole of Central and Northern Europe, and belted by land, since greatly uplifted, which then presented to the water's edge those climatal lconditions for which a sub-Arctic flora -- destined to become Alpine -- was specially organized, the difficulty of deriving such a flora from its paarent north, and of diffusing it over the snowy hills bounding this glacial ocean, vanishes, and the presence of identical species at such distant pooints remain no longer a mystery. Moreover, when we consider that conditions during the epoch referred to, the undoubted evidences of Continental observers, on the boounds of Asia by Sir Roderick Murchison, in America by Mr. Lyell, Mr. Logan, Captain Bayfield, and others, and that the botanical (and zoological as well) region, essentially northern and Alpine, designated by Professor Schouw that 'of saxifrages and mosses,' and first in his classification, exists now only on the flanks of the great area which suffered such conditions; and that, though similar conditions reappear, the relationship of Alpine and Arctic vegetation in the southern hemisphere, with that in the northern, is entirely maintained by 'representative', and not by identical species (the general truth of my explanation of Alpine floras, including identical species, becomes so strong, that the view proposed acquires fair claims to be ranked as a theory, and not considered merely a convenient or bold hypothesis."] -- Tr.

The p 349 elk, for instance, lives in the Scandinavian peninsula, almost ten degrees further north than in the interior of Siberia, where the line of equal winter temperature is so remarkably concave. Plants migrate in the germ; and, in the case of many species, the seeds are furnished with organs adapting them to be conveyed to a distace through the air. When once they have taken root, they become dependent on the soil and on the strata of air surrounding them. Animals, on the contrary, can at pleasure migrate from the equator toward the poles; and this they can more especially doo where the isothermal lines are much inflected, and where hot summers succeed a great degree of winter cold. The royal tiger, which in no respect differs from the Bengal species, penetrates every summer into p 350 the north of Asia as far as the latitudes of Berlin and Hamburg, a fact of which Ehrenberg and myself have spoken in other works.*

[footnote] *Ehrenberg, in the 'Annales des Sciences Naturelles', t. xxi., p. 387, 412; Humboldt, 'Asie Centrale', t. i., p. 339-342, and t. iii., p. 96-101.

The grouping or association of diffrent vegetable species, to which we are accustomed to apply the term 'Floras', do not appear to me, from what I have observed in different portions of the earth's surface, to manifest such a predominance of individual families as to justify us in marking the geographical distinctions between the regions of the Umbellatae, of the Solidaginae, of the Labiatae, or the Scitamineae. With reference to this subject, my views differ from those of several of my friends, who rank among the most distinguished of the botanists of Germany. The character of the floras of the elevated plateaux of Mexico, New Granada, and Quito, of European Russia, and of Northern Asia, consists, in my opinion, not so much in the relatively larger number of the species presented by one or two natural families, as in the more complicated relations of the coexistence of many families, and in the relative numerical value of their species. The Gramineae and the Cyperaceae undoubtedly predominate in meadow lands and stppes, as do Coniferae, Cupuliferae, and Betulineae in our northern woods; but this predominance of certain forms is only apparent, and owing to the aspect imparted by the social plants. The north of Europe, and that portion of Siberia which is situated to the north of the Altai Mountains, have no greater right to the appellation of a region of Gramineae and Coniferae than have the boundless llanos between the Orinoco and the mountain chain of Caraccas, or the pine forests of Mexico. It is the coexistence of forms which may partially replace each other, and their relative numbers and association, which give rise either to the general impression of luxuriance and diversity, or of poverty and uniformity in the contemplation of the vegetable world.

In this fragmentary sketch of the phenomena of organization, I have ascended from the simplest cellI -- the first manifestation of life -- progressively to higher structures. "The p 351 association of mucous granules constitutes a definitely-formed cytoblase, around which a vesicular membrane forms ia closed well," this cell being either produced from another pre-existing cell,** or being due to a cellular formation, which, as in the case of the fermentation-fungus, is concealed in the obscurity of some unknown chemical process.***

[footnote] *Schleiden, 'Ueber die Entwicklungsweise der Pflanzenzellen', in Muller's 'Archiv fur Anatomie und Physiologie', 1838, s. 137-176; also his 'Grundzuge der wissenschaftlichen Botanik', th. i., s. 191, and th. ii., s 11. Schwann, 'Mikroscopische Untersucungen uber die Uebereinstimmung in der Struktur und dem Wachsthum der Thiere und Pflanzen', 1839, s. 45, 220. Compare also, on similar propagation, Joh. Muller 'Physiologie des Menschen', 1840, th. ii., s. 614.

[footnote] **Schleiden, 'Grundzuge der wissenschaftlichen Botanik', 1842, th. i., s. 192-197.

[footnote] ***[On cellular formation, see Henfrey's 'Outlines of Structural and Physiological Botany', op. cit., p. 16-22.] -- Tr.

But in a work like the present we can venture on no more than an allusion to the mysteries that involve the question of modes of origin; the geography of animal and vegetable organisms must limit itself to the consideration of germs already developed, of their haabitation and transplantation, either by voluntary or involuntary migrations, their numerical relation, and their distribution over the surface of the earth.

The general picture of nature which I have endeavored to delineate would be incomplete if I did not venture to trace a few of the most marked features of the human race, considered with reference to physical gradations -- to the geographical distribution of contemporaneous types -- to the influence exercised upon man by the forces of nature, and the reciprocal, although weaker action which he in his turn exercises on these natural forces. Dependent, although in a lesser degree than plants and animals, on the soil, and on the meteorological processes of the atmosphere with which he is surroounded -- escaping more readily from the control of natural forces, by activity of mind and the advance of intellectual cultivation, no less than by his wonderful capacity of adapting himself to all climates -- man every where becomes most essentially associated with terrestrial life. It is by these relations that the obscure and much-contested problem of the possibility of one common descent enters into the sphere embraced by a general physical cosmography. The investigation of this problem will impart a nobler, and, if I may so express myself, more purely human interest to the closing pages of this section of my work.

The vast domain of language, in whose varied structure we see mysteriously reflected the destinies of nations, is most intimately associated with the affinity of races; and what even slight differences of races may effect is strikingly manifested in the history of the Hellenic nations in the zenith of their intellectual cultivation. The most important questions of the civilization of mankind are connected with the ideas of races, p 352 community of language, and adherence to one original direction of the intellectual and moral faculties.

As long as attention was directed solely to the extremes in varieties of color and of form, and to the vividness of the first impression of the senses, the observer was naturally disposed to regard races rather as originally different species than as mere varieties. The permanence of certain types* in the midst of the most hostile influences, especially of climate, appeared to favor such a view, notwithstanding the shortness of the interval of time from which the historical evidence was derived.

[footnote] *Tacitus, in his speculations on the inhabitants of Britain ('Agricola', cap. ii.), distinguishes with much judgment between that which may be owing to the local climatic relations, and that which, in the immigrating races, may be owing to the unchangeable influence of a hereditary and transmitted type. "Britanniam qui mortales initio coluerunt, indigenae an advecti, ut inter barbaros, parum coompertum. Habitus corporis varii, alque ex eo argumenta; namque rutilae Caledoniam habitantium comae, magni artus Germanicam originem adseverant. Silu ram colorati vultus et torti plerumque crines, et posita contra Hispania, Iberos veteres trajecisse, easque cedes occupasse fidem faciunt: proximi Gallis, et similes sunt: seu durante originis vi; seu procurrentibus in diversa terris, positio coeli corporibus habitum dedit." Regarding the persistency of types of conformation in the hot and cold regions of the earth, and in the mountainous districts of the New Continent, see my 'Relation Historique', t. i., p. 498, 503, and t. ii., p. 572, 574.

In my opinion, however, more powerful reasons can be advanced in support of the theory of the unity of the human race, as, for instance, in the many intermediate gradations* in the color of the skin and in the form of the skull, which have been made known to us in recent times by the rapid progress of geographical knowledge -- the analogies presented by the varieties in the species of many wild and domesticated animals -- and the more correct observations collected regarding the limits of fecundity in hybrids.**

[footnote] On the American races generally, see the magnificent work of Samuel George Morton, entitled 'Crania Americana', 1839, p. 62, 86; and on the skulls brought by Pentland from the highlands ot titicaca, see the 'Dublin Journal of Medical and Chemical Science', vol. v., 1834, p. 475; also Alcide d'Orbigny, 'L'homme Americain considere sous ses rapports Physiol. et Mor.', 1839, p. 221; and the work by Prince Maximilian of Wied, which is well worthy of notice for the admirable ethnographical remarks in which it abounds, entitled 'Reise in das Innere von Nordamerika' (1839).

[footnote] ** Rudolph Wagner, 'Ueber Blendlinge und Bastarderzeugung', in his notes to the German translation of Prichard's 'Physical History of Mankind', vol. i., p. 138-150.

The greater number of the contrasts which were formerly supposed to exist, have disappeared before the laborious researches of Tiedemann on the brain of negroes and of Europeans, and the anatomical investigations p 353 of Vrolik and Weber on the form of the pelvis. On comparing the dark-colored African nations, on whose physical history the admirable work of Prichard has thrown so much light, with the races inhabiting the islands of the South-Indian and West-Australian archipelago, and with the Papuas and Alfourous (Haroforas, Endamenes), we see that a black skin, woolly hair, and a negro-like cast of countenance are not necessarily connected together.*

[footnote] *Prichard, op. cit., vol. ii., p. 324.

So long as only a small portion of the earth was known to the Western nations, partial views necessarily predominated, and tropical heat and a black skin consequently appeared inseparable. "The Ethiopians," said the ancient tragic poet Theodectes of Phaselis,* "are colored by the near sun-god in his course with a sooty luster, and their hair is dried and crisped with the heat of his rays."

[footnote] *Onesicritus, in Strabo, xv., p. 690, 695, Casaub. Welcker, 'Griechische Tragodien', abth. iii., s. 1078, conjectures that the verses of Theodectes, cited by Strabo, are taken from a list tragedy, which probably bore the title of "Memnon."

The campaigns of Alexander, which gave rise to so many new ideas regarding physical geography, likewise first excited a discussion on the problematical influence of climate on races. "Families of animals and plants," writes one of the greatest anatomists of the day, Johannes Muller, in his noble and comprehensive work, 'Physiologie des Menschen', "undergo, within certain limitations peculiar to the different races and species, various modifications in their distribution over the surface of the earth, propagating these variations as organic types of species.*

[footnote] *[In illustration of this, the conclusions of Professor Edward Forbes respecting the origin and diffusion of the British flora may be cited. See the 'Survey Memoir' already quoted, 'On the Connection between the Distribution of the existing Fauna and Flora of the British Islands, etc.', p. 64. "1. The flora and fauna, terrestrial and marine, of the British islands and seas, have originated, so far as that area is concerned, since the melocene epoch. 2. The assemblages of animals and plants compositing that fauna and flora did not appear in the area they now inhabit simultaneously, but at several distinct points in time. 3. Both the fauna and flora of the British islands and seas are composed partly of species which, either permanently or for a time, appeared in that area before the glacial epoch; partly of such as inhabited it during that epoch; and in great part of those which did not appear there until afterward, and whose appearance on the earth was coeval with the elevation of the bed of the glacial sea and the consequent climatal changes. 4. The greater part of the terrestrial animals and flowering plants now inhabiting the British islands are members of specific centers beyond their area, and have migrated to it over continuous land before, during, or after the glacial epoch. 5. The climatal conditions of the area under discussion, and north, east, and west of it, were severer during the glacial epoch, when a great part of the space now occupied by the British isles was under water, than they are now or were before; but there is good reason to believe that, so far from those conditions having continued severe, or having gradually diminished in severity southward of Britain, the cold region of the glacial epoch came directly into contact with a region of more southern and thermal character than that in which the most southern beds of glacial drift are now to be met with. 6. This state of things did not materially differ from that now existing, under corresponding latitudes, in the North American, Atlantic, and Arctic seas, and on their bounding shores. 7. The Alpine floras of Europe and Asia, so far as they are identical with the flora of the Arctic and sub-Arctic zones of the Old World, are fragments of a flora which was diffused from the north, either by means of transport not now in action on the temperate coasts of Europe, or over continuous land which no longer exists. The deep sea fauna is in like manner a fragment of the general glacial fauna. 8. The floras of the islands of the Atlantic region, between the Gulf-weed Bank and the Old World, are fragments of the Great Mediterranean flora, anciently diffused over a land consistuted out of the upheaval and never again subjerged bed of the (shallow) Meiocene Sea. This great flora, in the epoch anterior to, and probably, in part, during the glacial period, had a greater extension northward than it now presents. 9. The termination of the glacial epoch in Europe was marked by a recession of an Arctic fauna and flora northward, and of a fauna and flora of the Mediterranean type southward; and in the interspace thus produced there appeared on land the Germanic fauna and flora, and in the sea that fauna termed Celtic. 10. The causes which thus preceded the appearance of a new assemblage of organized beings were the destruction of many species of animals, and probably also of plants, either forms of extremely local distribution, or such as were not capable of enduring many changes of conditions -- species, in short, with very limited capacity for horizontal or vertical diffusion. 11. All the changes before, during, and after the glacial epoch appear to have been gradual, and not sudden, so that no marked line of demarkation can be drawn between the creatures inhabiting the same element and the same locality during two proximate periods."] -- Tr.

The different races of mankind are forms of one sole species, by the union of two of whose members descendants are propagated. They are not different species of a genus, since in that case their hybrid descendants would remain unfruitful. But whether the human races have descended from several primitive races of men, or from one alone, is a question that can not be determined from experience."*

[footnote] *Joh. Muller, 'Physiologie des Menschen', bd. ii., s. 768.

Geographical investigations regarding the ancient 'seat', the so-called 'cradle of the human race', are not devoid of a mythical p 355 character. "We do not know," says Wilhelm von Humboldt, in an unpublished work 'On the Varieties of Languages and Nations', "either from history or from authentic tradition, any period of time in which the human race has not been divided into social groups. Whether the gregarious condition was original, or of subsequent occurrence, we have no historic evidence to show. The separate mythical relations found to exist independently of one another in different parts of the earth, appear to refute the first hypothesis, and concur in ascribing the generation of the whole human race to the union of one pair. The general prevalence of this myth has cause it to be regarded as a traditionary record transmitted from the primitive man to his descendants. But this very circumstance seems rather to prove that it has no historical foundation, but has simply arisen from an identity in the mode of intellectual conception, which has every where led man to adopt the same conclusion regarding identical phenomena; in the same manner as many myths have doubtlessly arisen, not from any historical connection existing between them, but rather from an identity in human thought and imagination. Another evidence in favor of the purely mythical nature of this belief is afforded by the fact that the first origin of mankind -- a phenomenon which is wholly beyond the sphere of experience -- is explained in perfect conformity with existing views, being considered on the principle of the colonization of some desert island or remote mountainous valley at a period when mankind had already existed for thousands of years. It is in vain that we direct our thoughts to the solution of the great problem of the first origin, since man is too intimately associated with his own race and with the relations of time to conceive of the existence of an individual independently of a preceding generation and age. A solution of those difficult questions, which can not be determined by inductive reasoning or by experience -- whether the belief in this presumed traditional condition be actually based on historical evidence, or whether mankind inhabited the earth in gregarious associations from the origin of the race -- can not, therefore, be determined from philological data, and yet its elucidation ought not to be sought from other sources."

The distribution of mankind is therefore only a distribution into 'varieties', which are commonly designated by the somewhat indefinite term 'races'. As in the vegetable kingdom, and in the natural history of birds and fishes, a classification into many small families is based on a surer foundation than p 356 where large sections are separated into a few but large divisions; so it also appears to me, that in the determination of races a preference should be given to the establishment of small families of nations. Whether we adopt the old classification of my master, Blumenbach, and admit 'five' races (the Caucasian, Mongolian, American, Ethiopian, and Malayan), or that of Prichard, into 'seven races'* (the Iranian, Turanian, American, Hottentots and Bushmen, Negroes, Papuas, and Alfourons), we fail to recognize any typical sharpness of definition, or any general or well-established principle in the division of these groups.

[footnote] *Prichard, op. cit., vol. i., p. 247.