' According to the estimates of the Rockefeller Sanitary Commission about 940,000,000 of the 1,600,000,000 people of the world live in areas where hookworm disease is prevalent. Half the people within the tropics probably suffer from the disease at all times, and many others have it at some time during their lives. It stunts the growth of children, retards their mental development, and makes adults anemic and incom petent. In Costa Rica 66 laborers before being treated for hookworm disease normally cultivated 563 acres of coffee monthly. After treat ment they cultivated 750 acres. In India the amount of work increased 20 per cent on one estate and 50 per cent on another, and on both was of better quality than before the laborers were treated; reports from British Guiana indicate that the efficiency of the laborers employed by one company increased from 25 to 50 per cent after measures to eradi cate the hookworm were put into operation.
The harm done by insects and bacteria in tropical countries can scarcely be measured. Yellow fever, which formerly killed people by the hundred thousand, is carried by a mosquito which thrives only in low latitudes. Essentially the same is true of malaria, which occurs sporadically and of mild character in cool countries but becomes even more dangerous than the hookworm disease within the tropics. The old idea that tropical people are immune to such diseases is no longer accepted by students of tropical medicine. Adults, to be sure, are often immune, but frequently at the expense of vitality. Vast numbers of children die in infancy and early childhood from malaria or from diseases to which the weakening effect of malaria renders them liable. Others suffer and recover, but they bear the results with them to the grave in the form of enlarged spleens, anemia, and dulled mentality. Add to these diseases the irritating bites of flies, ticks, and other noxious insects and it is evident that a community afflicted with such disorders cannot be efficient or rise high in the scale of civilization.
(d) Ignorance and Lack of Hygiene.—The poor diet, debilitating climate, and prevalence of diseases prevent tropical people from im proving their own condition. They may know that keeping clean, procuring a varied diet, and suppressing mosquitoes and vermin would greatly improve their health, but they lack the mental and physical vigor to do these things. They live in a vicious circle where climate causes poor diet and debilitation, and favors harmful parasites. These cir cumstances lead to disease, and the diseases weaken the people still more so that they have not energy enough to improve their own con dition. Many good authorities believe that unsanitary practices
are the most important and also the most easily overcome of all the tropical handicaps.
(7) Difficulties of Tropical Transportation.—In most tropical coun tries transportation is very backward. Heavy rains, superabundant vegetation, weakness among the animals, and lack of vigor and inven tiveness among the people make it difficult to build and maintain roads, or to lay up the capital which is essential if the means of transportation are to be permanently effective. For example, on the Madras Railroad in India 40 per cent of the ties have to be renewed each year; on the Tehuantepec Railway work had to be suspended because of the loss of workers through disease; and during the building of the Indian railway from the Portugese port of Goa to the main British system 63,000 patients were treated. Because of such conditions tropical countries contain scarcely a mile of macadam road, tram line, or railway which has not been either built with capital and machinery from outside the tropics or superintended and equipped by people from cooler climates.
(8) The White Man in the Tropics.—The preceding sections show that conditions of race, climate, vegetation, health, and transportation have prevented tropical people from making any important contribution to the world's business when left to themselves. Nevertheless tropical regions are today the greatest unused reservoir of wealth. Such tropical products as sugar, rubber, quinine, cocoa, dye-wood, and coffee are becoming an absolute necessity, while tropical lumber may soon be of great importance. The only way to procure such products is for white men to go to tropical countries and live there, at least temporarily. This raises the following questions which are among the most important problems of tropical business: (1) What is the effect of a temporary sojourn within the tropics upon white men in positions of responsibility? (2) Can white laborers and farmers permanently colonize within the tropics, and is it advisable that they should do so? (3) In what ways can the efficiency of the native people be most improved? There is some difference of opinion as to the answers to these ques tions, partly from lack of knowledge and partly because relatively health ful and invigorating islands like Hawaii are as different from the un healthful forests of the Amazon as England is from Egypt. In what follows we shall speak of the regions such as the East Indies, southern India, and northern South America, where the possibilities of plantation agriculture are greatest.