built his towns. The Atlantic Ocean has a drainage basin of over 19,000,000 square miles, while the Pacific has only 8,660,000. Rivers facilitate trade and intercourse. Africa has nothing to compare with the Amazon or the Missouri. The Yangtse and Hoangho are the source of China's prosperity as was the Nile of ancient Egypt.

Islands in favorable climes are densely populated. Java has a density of 587 to the square mile; Gilbert Islands of Great Britain, 1254. The Islands of Denmark have a density of 269 as compared to 112 in Jutland on the mainland. Safety and fish are probably the two chief factors in causing this density.

Until the sixteenth century the oceans were practically impassable, until the nineteenth, impassable to all but a handful; yet man has at some time and somehow made his way to all habitable parts of the earth.

2. Occupation." Geographic conditions influence the economic and social development of a people by the abundance, paucity or general character of the natural resources, by the local ease or difficulty of securing the necessities of life, and by the possibility of industry and commerce afforded by the environment." 18 The history of America affords endless illustrations of the truth of this statement. The New England States turned from agriculture to manufacturing and shipping, they found slavery generally unprofitable and they developed the town and town meeting as their type of government; while substantially the same people in the south clung to farming largely because of the adaptability of the land to tobacco and cotton, welcomed the Negro slaves and made the county the unit of government, the scattered house

18 SEMPLE, E. T. Influences of Geographical Environment, p. 43.

hold the ideal of life. There is no more interesting contrast in our history than the antagonisms between the hill whites and the lowland slave owners, indicated by such events as the separation of West Virginia from the mother state and by the fact that some of the mountain counties of Tennessee furnished as large a percentage of Union volunteers in proportion to population as did any northern district. Since man must live on the "free goods" of nature to be had by the taking or must produce for himself, it is easy to see that the life of the Eskimo must differ widely from that of the West African Negro. In Polar regions man must even today be a fisher and hunter, living on meat alone, unless he keep in touch with other people, when he may be a miner. On the whole the temperate zones have been most favorable to him, and no great civilization has arisen as yet in the tropics. By fixing the opportunities nature goes far towards determining the type of the development.

3. Direct Physical Effects.-"We can hardly err in attributing the great lung capacity, massive chests and abnormally large torsos of the Quichua and Aymara Indians inhabiting the high Andean plateaus to the rarefied air found at an altitude of 10,000 or 15,000 feet above sea level." 19 It is well known that the different parts of the body grow and mature at different rates and times. If food, heat or clothing be lacking, a stunting may result. Alpine or boreal races are usually shorter than those of the lowlands of warmer regions. Transfer to a new country may cause marked changes for reasons not yet fully understood. In America the descendants of Europeans are seemingly considerably larger than the average at home. This was indicated by the soldiers in

the Civil War. Professor Boas of Columbia University has been studying recent immigrants. He writes: "I think, therefore, that we are justified in the conclusion that the removal of the East European Hebrew to America is accompanied by a marked change in type, which does not affect the young child born abroad, but which makes itself felt among the children born in America, even in a short time after the arrival of the parents in this country. The change of type seems to be very rapid, but the changes continue to increase so that the descendants of immigrants born a long time after the arrival of the parents differ more from their parents than do those born a short time after the arrival of the parents in the United States." 20 These changes are in the shape of the head form, hitherto considered very fixed. The Hebrew becomes more long-headed, the Italian more roundheaded. Such striking conclusions need a verification, yet lacking, before being unqualifiedly accepted. The Snake Indians of the Rockies differed much in stature from the Blackfeet or Sioux of the plains.

The environment by fixing occupation may in large measure determine physical characters. Darwin attributed the thin legs of the Indians of the Paraguay River to the constant canoe life. The man who lives in the saddle acquires a rolling gait when walking as does the sailor. The stooping shoulders of the farmer are likewise due to his trade.

A very important and practical question which cannot be finally answered at the present time is whether the blond types of humans can survive in the tropics. In part this is a question of control of disease but it has other aspects. There is some reason to believe that the

20 BOAS, F. Changes in Bodily Form, p. 52.

white races cannot permanently endure the constant heat and the effects of the actinic rays of the sun. "Consequently we find that man is invariably covered with a pigment which acts as an armor to exclude the more harmful short rays, and moreover the amount of pigment is in direct proportion to the intensity of the light of the country to which his ancestors have proved their adjustment by centuries or millenniums of survival in health and vigor. It is a simple matter of mathematics to show that the intensity of light under the zenith sun in the tropics is the greatest and that the proportion of rays per unit of surface diminishes as we go north in proportion to a function of the latitude. In addition to this the further from the tropics we go the greater is the layer of air which the rays must pass through and the more of them which are absorbed. . . .. Undoubtedly the Negro, when in the shade, is able to radiate heat better than whites and this enables him to keep cool in the tropics, but puts him at a disadvantage in the north where a white man can keep warmer with less clothing and less fire in the house. But it is a secondary cause enhancing the first, because when it comes to a question of light and cold, nature makes no mistake, but selects a color to exclude the light. Hence in all cold, light countries, i.e., steppes, plains and the arctics, there is pigmentation of a color in the lower end of the spectrum, red or yellow, with variations of brown, olive or copper. All these red and yellow colors undoubtedly enable the native to conserve his heat almost as well as the white man, and at the same time, exclude the dangerous short waves." 21 Though the individual man may prosper for a time in the tropics

21 WOODRUFF, C. W. Effects of Tropical Light on White Men, p. 85 ff.

it may be that there is some deep seated reason for the absence of third generation Europeans in India. Our experience with the polar regions is too meager to give us the basis for an opinion as to their effects on the race.

The barometric pressure at sea level is 29.38. The ordinary changes in pressure are too slight to be noted. Yet most people have momentary discomfort when descending in an express elevator from the top of a high building. Serious results ensue from sudden changes of altitude. During the construction of the tunnels under the Hudson one physician is stated to have seen 2,400 cases of "caisson disease," popularly known as the "bends," resulting from working under unusual pressure; while Younghusband's account of the British expedition to Thibet gave many amusing accounts of the attempts of sea level dwellers to march and fight at high altitudes. Railroad circulars seldom mention the danger of going to the top of Pike's Peak, but physicians are better informed. Prolonged residence in high altitudes is thought to produce definite effects, inasmuch as the blood gets more oxygen and gives off more carbon dioxid.

4. Physiological Effects.-In spite of the considerable overlapping with the purely physical effects it seems wise to consider certain types of influences under this caption. Every one is conscious that his feelings vary from day to day and that they are influenced by climatic conditions. Of Buenos Aires, Dexter writes:

"By the time the north wind has reached the city it has become so overcharged with moisture that everything becomes intensely damp. The effects produced in the human body are a general lassitude and relaxation, opening the pores of the skin and inducing great liability to colds, sore throat and all consequences of checked perspira