T RADITIONAL theories of international trade have explained the existence and composition of trade between countries in terms of international differences in production functions and factor endowments. More recently, increasing attention has been paid to other influences, which lie at the fringe of the traditional theory. These include the specific character of factors such as natural resources, the influence of tariffs and other restrictions on trade, and differences in size of country. Empirical studies of the composition of international trade have tended to test hypotheses about only a single one of these determinants. Yet it seems unlikely that they are mutually exclusive; one should expect several different influences simultaneously to play a part in shaping any given flow of trade. Accordingly, we have carried out an analysis of a particular trade flow to try to assess their relative empirical importance. The specific trade flow with which we are concerned is that between the Republic of Ireland and the United Kingdom. We have chosen to analyse this trade flow for the following reasons: First, we are fortunate to have detailed data on the flows of merchandise trade between Ireland and the United Kingdom. This information can be linked to the input-output tables of each country, which are comparable at a classification level of forty-seven sectors. We also have detailed and reliable estimates of Irish factor endowments.' Secondly, Irish trade with the United Kingdom forms a large part of her total trade (70 per cent of merchandise exports, and 50 per cent of merchandise imports in 1964). Exports from individual Irish sectors of production frequently account for a large share of sector output, while imports generally form a high proportion of the output of the domestic sector with whose products they are competing. Thirdly, the Irish economy is a small tradedependent economy whose exports have a large primary commodity content. The composition of its trade with its much larger and industrialised trading partner may not be untypical of the position in which so many developing countries find themselves with respect to their more advanced trading partners. It is worth emphasising that the small trade-dependent economy is typical of the great majority of countries. We begin with an empirical test of the Ricardian hypothesis of comparative advantage in its classical two-country, multi-commodity formulation. In the second section of the paper, we present the results of a number of tests concerned with hypotheses about factor proportions. The third section examines the influence of natural resources, and the paper concludes with an account of the role of trade restrictions.

T NHE structure of production of an economic system, represented by the matrix of input-output coefficients, has traditionally been held to be determined by technology. Thus the coefficients are sometimes called coefficients. If this is, in fact, the case one should expect to discover a productive structure which is common to all economic systems having a like technology.' For example, one should expect to find certain characteristics of the input-output matrices of all industrialized countries, which have a technological origin. Previous studies have compared the productive structure of different economic systems in purely economic, or even arithmetic terms, so that they may fairly be described as taxonomic. On the other hand, this paper suggests that there are certain fundamental elements which may be found in the productive structure of modern economic systems which are purely technical in character. It is demonstrated that the economic systems of Japan and the United States, although superficially dissimilar, contain almost identical patterns of industries which are strongly interrelated. This pattern, or framework, of productive relations has several interesting properties, which are found to be shared by the pattern of interindustry relations in other economies. The theoretical implications of this discovery are briefly discussed.

"Biodiversity prospecting" has been touted as a mechanism for both discovering new pharmaceutical products and saving endangered ecosystems. It is unclear what values may arise from such activities, however. Evidence from transactions is incomplete and existing theoretical models are flawed. We calculate an upper bound on the value of the "marginal species." Even under favorable assumptions this bound is modest. Slightly modified assumptions lead to drastically lower estimates. We extend our findings to the value of the marginal hectare of habitat and find that the incentives for habitat conservation generated by private pharmaceutical research are also, at best, very modest.

"Biodiversity prospecting" has been touted as a mechanism for both discovering new pharmaceutical products and saving endangered ecosystems. It is unclear what values may arise from such activities, however. Evidence from transactions is incomplete and existing theoretical models are flawed. We calculate an upper bound on the value of the "marginal species." Even under favorable assumptions this bound is modest. Slightly modified assumptions lead to drastically lower estimates. We extend our findings to the value of the marginal hectare of habitat and find that the incentives for habitat conservation generated by private pharmaceutical research are also, at best, very modest.

Wassily Leontief, Alison Morgan, Karen Polenske, David Simpson, Edward Tower, The Economic Impact--Industrial and Regional--Of An Arms Cut, The Review of Economics and Statistics, Vol. 47, No. 3 (Aug., 1965), pp. 217-241