domestication can be assigned with any safety to the cosmopolitan dog, cat, duck, goose, etc. It is, however, certain that none of these latter, in the cultivated forms which we know, originated in the Americas or Australia; in these continents what domestication there was, was local and so remained; even the llama of Peru never made its way outside of the South American plateaus. The weight of probability goes to show that the development of the best breeds of both plants and animals is possible only to people of a relatively high civilization, as evidenced by density of population, sedentary life, intellectual superiority, technical skill in isolation and selection, and the like.

The artificial distribution of the domesticated flora and fauna will appear under later sections of this book (§§ 214, 234, 239, 240, 241, 242, 243). It may, however, be reiterated here that the laws of acclimatization (§§ 143, 145 above) have to be strictly observed, and that, in general, artificial distribution consists in the conveyance of the plant or animal to a region essentially identical with the original habitat, or artificially rendered so. The tree from whose bark the drug quinine is derived demanded the drenching rains of the eastern Andes; and it would not thrive elsewhere until the British had ferreted out, in their broad dominions, the almost exact counterpart of its native environment. If the new home is identical or nearly identical with the old, of course there is no hindrance to this spread; but with every difference, adjustment to which requires much artificial aid, the growing element of cost renders what is physically difficult commercially impossible.

INORGANIC MATERIALS

161. Influence of the distribution of inorganic materials. Thus far in this chapter we have considered only organic products, and we have treated of them first, inasmuch as the conditions of their life and distribution are so closely connected with the topic of climate with which we began. But there are many inorganic substances which likewise enter into trade because they serve either as repair to the waste of the body or as essential materials in the development of the apparatus of civilization. The distribution of water (§§ 81, 94) and of salt is of prime importance to man as an animal; and that of the useful rocks and ores (38) to man as a social being. The value of flint and clay deposits to early man is proved both by the series of combats for the possession of the deposits and by the extent of trade in the articles themselves (cf. § 182). The same might be said of salt, shells, and other like commodities. And when the desire to possess the precious

metals and stones became strong, the disposition of these treasures exerted a strong influence upon local and general history. For long ages the legend of the Gold and Silver Islands attracted the world, and the Discoveries Period was full of the search for sudden wealth in the shape of deposits of the precious metals or of peoples who could be robbed of the products which they had extracted from mines. Whole settlements have risen about productive lodes, and then dwindled with their exhaustion. Prospectors and adventurers rushed to the Indies, Spanish and Portuguese America, California, Australia, South Africa, Alaska, to be followed later, in some cases, by those who represented more settled occupations, and then by genuine settlers. Take especially the case of California. The rush of the " forty-niners" resulted in the creation of a wild, irregular, and lawless community. But it drew men to an almost unoccupied land, to learn of its value in lines other than those of the metal-extractive industries; and exploitation was gradually modified into rational development of resources. Development of national interests on the Pacific coast then motived those extraordinary undertakings in the construction of railroads which ended by binding together in national unity and common interest regions 3000 miles apart and separated by barriers which, except for an extraordinary attraction, would have remained long insuperable (cf. § 302). Thus the presence of the precious metals has given a start to the settlement of countries which have later taken a higher place in the making of history and in the world of trade.

The history of American mining-towns presents many examples of the determining effect of mineral deposits. Butte, Montana, is a city of 62,000 inhabitants, supported by copper underlying about one square mile of land surface. The metal forms the sole raison d'être of this considerable settlement, for in other respects the region is unproductive and unattractive; without the mines the locality would support with difficulty a population of one hundred souls. The mineral deposits of Nevada occur beneath strips of land a few hundred feet in width and in the midst of a hopeless desert, but they have formed plausible pretext for adding a State to the Union and two Senators to Congress. The decline of the lodes has now reduced Virginia City to a population of 2500, as against 11,000 in 1880, when it was one of the busiest cities in America, in the midst of a superlatively "booming" State. In 1900 Nevada was credited with a population of 42,335 — a figure somewhat under that for 1870; thus this State, with an area twice that of New England, has less population than Waterbury, Connecticut.1

But it is not alone the precious metals which have determined human history. The wealth of England has lain in good part in the

1 Gregory and Keller, "Controlling Conditions of Commerce," Harper's Monthly, March, 1908,

natural advantage it has possessed in the juxtaposition of its coal and iron deposits (§ 331), an advantage which accrued to us of America only after the development of rapid and cheap transportation had neutralized the factor of distance - when the physically difficult had been rendered sufficiently easy to become commercially possible. One might further instance the early connection of England with the Mediterranean nations, owing to the presence of tin in Cornwall; the prosperity of many sections of the world, due to the discovery of petroleum; the importance of the copper mines in the development of Lake Superior regions; and so on. The great prosperity of Pittsburg, Pennsylvania, owing to the simultaneous presence of coal, iron, petroleum, and facilities for water and land transportation, is a case of a plurality of favoring conditions.

We have now considered climate and the character of flora and fauna as natural conditions which directly influence the life and activities of man, or which call forth in him his special powers of adaptation through intellectual processes; and we have touched upon the distribution of inorganic products. The bearing of all this upon the development of trade is obvious; if it affects man's very life it certainly affects all his activities; and if it affects the sum of his activities it certainly affects trade.1 We turn now to another set of conditions still partially connected with climate, but depending more directly upon the forms of land and the presence or absence of water.

1 The data of trade assembled in the later pages of this volume sufficiently demonstrate this conclusion; it is the chief object of our writing to place behind the bald facts and statistics of commerce the underlying explanations which will render the study of the actual data something more than an exercise in ineffectual memorizing. It is manifestly impossible in this place to deal with more than generalities; but it is suggested to both teacher and student that a correct apprehension of these generalities will help them to explain local and variant cases for themselves.

CHAPTER IX

ENVIRONMENTAL INFLUENCES (Continued)

TOPOGRAPHY, DISTRIBUTION OF WATER, ETC.

162. Topographic influences in general. Diversifications of the surface of the land (§ 22 and Chapter II), determining as they do the forms of coast line, the general direction of drainage, avenues of communication, etc., exercise a very strong influence upon the life of man. The effect of elevation on climate has been explained in a former chapter; thus we may have a temperate climate within the tropics or even under the equator, and resulting phenomena of human life approximately characteristic of such climate (§§ 51, 112, 148). The only advanced civilization native to the Americas was developed upon high plateaus, in Mexico and Peru; Montezuma's capital lay at an altitude of about 7500 feet and that of the Incas was some 5000 feet higher. Altitude, however, with its accompanying thinness of air, also exerts a strong influence upon the human organism, rendering a people less energetic and progressive. Horses brought from New York could not race on the plateau of Anahuac; and men are said to be incapacitated for the most strenuous efforts. The porters of Mexico city used to carry far lighter loads than did those of Vera Cruz. The civilization of plateaus, for this and other reasons (isolation, etc.; cf. §§ 166, 170), has never reached the height of that developed in lower flat regions: contrast Mexico, Peru, or Tibet with China or Egypt. High plateaus are, as a class, the most unfruitful parts of the earth. Since "every elevation of ground diminishes the density of population, or, as it were, loosens it . . ., it is very significant that, of all the quarters of the world, Europe has the lowest mean altitude (§ 37). It is essential to all progress of culture that men should not be separated by great distances."1

Again, the influence of altitude upon the life of many virulent discase germs is very marked: yellow fever, with its insect agency of propagation, never ascended higher than about 3600 feet some say far less above the sea level; typhoid was unknown upon the

1 Peschel, Races, p. 509.

Cordilleras; lofty stations are favorable to recovery from tuberculosis of the lungs.

Man is, as it were, a deep-sea inhabitant of an ocean of air; he is limited as to his expansion, not only in a perpendicular direction but laterally over the floor of his ocean as well (§§ 55, 56, 59). He can attain great altitudes — he can climb Chimborazo (over 20,000 feet) or ascend to a height of over 35,000 feet in a balloon - but he cannot live there. His heart-beat is quickened, and the symptoms indicating that the organism is out of its proper environment are exhibited. The highest inhabited places are not of an elevation of over 15,000 feet. In Italy only 0.3 in 1000 people live at an elevation of over 5500 feet, and only 7.3 per 1000 above 3600; elevations of 0-160 feet and 320-1000 feet show figures of 264 and 272 per thousand, that is, they harbor, taken together, over one-half of the Italian population. And, significantly enough, elevations in warmer regions are of about the same populousness as the colder latitudes to which they correspond: Alpine regions of an elevation of about 1600 feet show a density of population corresponding to that of Norway; high Peru and Mexico (above 8000 feet) have the density of Spain.

The following table shows the density of population at certain altitudes in the United States (1880):

The Mohawk valley, which cuts to a depth of about 140 feet between the mountains, exhibits a strip of country numbering 45 to 90 inhabitants per square mile between two strips numbering from 6 to 18. Naturally the conditions of communication have a good deal to do with these facts, as will presently be seen; but the underlying influence of altitude is not thereby minimized.1

Other effects of diversification of land forms might be cited, for instance, that affecting rainfall and the formation of deserts (§§ 115, 120, 125). Mountains generally have a dry and a wet side, and if they shut off an interior, as in Australia (§ 361), from the vapor-bearing winds, aridity must result. In this place, however, we wish rather to

1 Most of the above figures are from Ratzel's Anth., I, 311 ff.; II, 211 ff.