Climatic Values of Here again in Panama (and this is not less true of the Central American states) we find that even a moderate elevation mitigates the tropically op pressive conditions that are notorious in the lowlands. The importance of this consider ation becomes apparent when we reflect that in much more than one-half of the entire land area in the New World between the Tropics of Cancer and Capricorn nature assigns the con trol of temperatures to mere altitude or to the almost equally permanent influence of oceanic and aerial currents. But in the vast highlands of Latin America one learns by experience, if he has not learned through previous study, that the pure and rarefied air is had for any weakness of the heart, and, even when there is no such weakness, produces what is commonly known as soroche (anoxxmia or mountain sickness). It is worth while to note quite care fully the effects of the change from sea-level to these great altitudes, since the experience bears directly upon the question of the value of these uplands as regions where civilized men can live and work successfully. We ob serve, as first effects, that the skin becomes rather dry and the digestive processes arc de ranged — with consequent pains and penalties. We must add the following symptoms: lassi tude, loss of appetite, aversion to all forms of physical effort and drowsiness. The heart finds its steady job a hit harder than usual, and one gets out of breath too quickly, the air seem ing to supply the lungs with innutritious food. After a long voyage a traveler in vigorous health suffers to this extent — that is, slightly and for a few days at least — on making a rapid and radical change. But in a week or so these symptoms disappear, the traveler gets acclimated and should find no trouble in mak ing any physical effort that the situation calls for. Quite the contrary, in fact. We enjoyed mountain-climbing, long walks, long and hard riding, at altitudes of about 12,000 feet for sev eral weeks and ranging from 10,000 to 16,000 feet during two months. The impression we receive in regard to the people living in Andean towns (for example) situated at altitudes of 7,000 to 14,000 feet is that they, as a rule, with some exceptions of irregular liyes, are not in jured by the climate.
Naturally healthful regions are the follow ing: 1. The extensive region south of a line drawn from ocean to ocean through the cities of PaysandU and Valparaiso, including all of southern Argentina and Chile. 2. The uplands of southeastern Brazil. 3. The Andean habit able districts, including many valleys and cuencas, at altitudes ranging from 6,000 to 12,000 feet. 4. In Venezuela, Central America and Mexico, the districts, often fertile and ex tensive, at altitudes ranging from 2,500 or 3,000 to 7,000 feet, more or less. 5. Portions of the West Indies receiving the full benefit of the trade winds and ocean currents. Unfortu nately it is necessary to note the prevalence of such diseases as typhoid fever in cities and towns whose favorable situation in temperate uplands does not safeguard them against the consequences of neglecting sanitary regulations. The tropical conditions in the low-lying parts of Central America and the northwest coast of South America (to and including the Gulf of Guayaquil) are unfavorable to health chiefly be cause enormous deposits of alluvion and exces sive rainfall offer ideal conditions for the prop agation of disease-bearing insects. Yellow fever and malarial fevers have therefore long been regarded as endemic. Similar conditions are found in the great Amazon Valley and on the tropical Brazilian coast between the Atlantic and the highlands of the interior. Successful efforts to combat and control these fevers have been made at focal points — at Santos and Rio de Janeiro, at Panama, etc.— hut much still re mains to he done. Annual rainfall is most ex cescive in amount at Pernambuco and Iquitos in Brazil, at Greytown in Central America, and in the territory of Magellan, in southern Chile; it is least on the Peruvian littoral and in north ern Chile (q.v.) ; it is as a rule moderate in the interior of Argentina. Dense fogs, called garfias, supply the place of rain (but only to a slight extent) in the arid west coast regions just mentioned. Ever since the discovery of the New World the fact has been observed that the most vigorous races gained their de velopment in the extreme south (region number I) and in the temperate or relatively cold up lands (regions 3 and 4). It is not less interest ing to observe that the most progressive and vigorous element of which we have any record in the early history of Brazil had its home in region number 2. For the exceptionally fine
and temperate climate of Uruguay, see the article devoted to that country.
Fauna and The highlands of the northern and central portions of Mexico are included in the Nearctic Region and their fauna is classed with that of all temperate and Arctic North America; but naturalists, grouping to gether all other parts of Latin America, in the wider sense of that term, distinguish the group (thus composed of Central America and Panama, the Mexican lowlands, the West Indies and South America) as the Neotropical Region. A valuable study entitled Zoolog. ical Expedition to South America,' by W. E. Agar (in Royal Philosophical Society of Glas gow Proceedings, Vol. XL, pp. 53-65, 1909), contains an expression of its author's opinion to the effect that the Neotropical is, of all those regions into which zoologists divided the world in accordance with their fauna, by far the most interesting. And this is true although only four families of the ungulates are represented: the pigs by the peccary, the cervidte by a few species of deer, the camels by the llama, and finally there is the tapir; while the beasts which we may call characteristic of the country are such forms as the opossum, armadillo, ant eater and sloth, all very lowly organized ani mals.
Our interest in this fauna is deepened when, at the suggestion of the same writer, we ex amine its history in past geological ages. °The past history of the mammals [in general, i.e., in all regions] shows us that, broadly speaking, most new forms arose in the North Polar regions (which we know were much warmer then than now) and spread thence southwards, exterminating to a large extent the more primi tive earlier forms, and being sometimes ousted in their turn by new forms migrating south wards. Now, the primitive mammals which arose in the Northern Hemisphere seem to have reached South America, not across the Isthmus of Panama — for we known that the whole south portion of North America was sub merged at this period — but probably by means of a land connection across the Atlantic with Africa. Whatever may have been the exact nature of this connection between South Amer ica and the other land-masses of the globe toward the end of the secondary geological epoch, it is certain that it was soon broken through and that South America was com pletely isolated during the whole of that period in which the most active evolution of mammalia was taking place in other parts of the world. The few low mammals which had reached South America before it became isolated evolved a very peculiar mammalian fauna, including such forms as the giant sloth or Megatherium, and Glyptodonts like gigantic armadillos, which, however, never reached a very high grade of development, such as the mammals in the more desperate struggle for existence that was going on in other parts of the world were attaining?) But finally a new path of approach to this com pletely isolated continent was constructed. Dur ing the end of the Miocene period the emer gence of the Isthmus of Darien or Panama allowed the influx of more highly specialized forms from the Northern Hemisphere; and accordingly we find that fossiliferous beds dating from this period hold the remains of lions, the sabre-toothed tiger, dogs, bears, llama, deer, horses, tapirs and peccaries — animals that had been abundant in other parts of the globe for ages before, but had been unable to reach South America for the reason mentioned. These invaders °established themselves to a great extent at the expense of the old typical South American fauna. Remains of this original fauna, however, still survive in the opossum, armadillo, ant-eater and sloths, while the new forms, which are now far more abun dant, both in numbers and species, include such forms as the deer, tapir, peccary, puma, jaguar, wildcats, dogs, etc." Ex-President Roosevelt invites our attention particularly to the fact that South America has the most extensive and most varied avifauna of all the continents. The rhea, or American ostrich, and the fur seal were studied with true interest by Dr. John Augustine Zahm in Uruguay. For the dis tinctive fauna and flora of an important part of the west coast, see CHILE. On the other hand the countries of Central America, forming borderlands between the greater North and South, naturally show some results of the orox imity of the former; nevertheless the influence of the latter has been in these respects so much the more potent that Central America is with good reason assigned to the Neotropical Region, as we have said above.