"There are five general problems which the laborer or employer in tropical countries, who is anxious to build cheap but proper houses, has to meet. The first is to provide adequate protection against the heat. As in northern countries it is necessary to shut out the cold winds and generate and conserve artificial heat within the house, so in tropical countries it is equally important to let in the breezes and to clear out any artificial heat that may arise. "The second problem is to provide protection against the frequent tropical rains. This is especially important in tropical countries that have a protracted rainy season, as it is often difficult to shut out the rain without also shutting out the fresh air. "The third problem is the provision of adequate sanitary facilities. Due to the heat in southern countries and to the humidity that prevails during certain seasons of the year, this problem is more difficult of solution and likewise more important than in countries farther north. "The fourth problem is that of securing cheap and durable building materials. In a land like Porto Rico where tropical shrubs and the palm are practically the only woods that the laborers are able to obtain, we must not expect the same solid, commodious habitations which are found in northern countries where the pine and hemlock abound. "The fifth problem, perhaps as important as any of the preceding and certainly as difficult to remedy, arises partly from the generosity of nature herself. People can live in tropical countries in almost any form of habitation. Cold winters have not obliged the poorer classes to be adepts in house construction. Poverty has forced them to live as cheaply as possible. Naturally, the laboring classes engaged in tilling the soil still make their homes in the cheapest forms of huts. This problem has, therefore, three aspects--an over-indulgent climate, poverty, and a lack of opportunity by the poorer classes to learn better methods of house construction. "In Porto Rico we have, in addition to the problems mentioned above, two special conditions which have influenced the form and quality of our laborers' houses. The first is that the seasonal character of many of our agricultural industries forces the laborers to migrate from one section to another in order to find work and, naturally, they are not inclined to go to the expense and exertion of building substantial homes. The second, and more important, arises from the fact that the greater part of our laborers do not own the land their houses are placed upon and, being subject to ejection at the will of their landlords, they have no incentive to beautify or improve their homes.