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Background: This comparative study hypothesize there are differences betweenultrasound guided retroclavicularand proximal infraclavicular approaches for brachial plexus block for surgeriesinvolving lowerpart of arm, elbow, forearm and hand with the use of tourniquet.Method: About 36 patients randomly allocated into 2 groups, first group block done through retro-clavicularapproach (RCB) and the other group done by using proximalinfraclavicular block (PIB).In RCB groupneedle inserted posterior to the clavicle and directed posterior to the first part of axillary artery. In PIBneedle inserted from lateral to medial after abduction of the arm more than 90° where the cords are clusteredtogether.Results: Block performance time was (6.11±2.58) and (6.05±2.61) for RCB and PIB, respectively withoutsignificant difference (p= 0.94). The onset of sensory was (12.8±1.4) and (11±2.3) for RCB and PIB,respectively. For motor onset (17.4 ±2.3) and (15.3±3.3) and there is significant difference between bothgroups (p=0.009 and 0.04), respectively. There was no significant difference in block-related pain betweenthe two groups (p=0.809) VRS for RCB was (1.41±0.712) and for PIB was (1.32±0.67). Tourniquetpainreported by the patientfor RCB was 1.24±0.56 and for PIB was 1.11±0.315, there is no significant differencebetween both groups (p=0.392)Conclusion: Ultrasound guided BPB by retro-clavicular and proximal approaches are with a comparablequality of surgical anesthesia for operations of the lower arm, elbow, forearm and hand with the use oftourniquet, the onset of surgical anesthesia is earlier for PIB, the RCB is preferred for patients who cannotabduct the arm.

The numerical simulation of MHD mixed convection due to a rotating circular solid cylinder in a trapezoidal enclosure filled with a Cu-water nanofluid saturated with a porous media was presented in the current paper. The midpoint of the top wall of the enclosure is considered as a center of a cylinder which has a different radius. The remaining of this wall is considered adiabatic. The bottom wall is heated with the temperature of Th and moving to the right hand, while sidewalls are kept isolated and stationary. The Hartmann number, thermal conductivity ratio, angular rotational velocity, Richardson number, inclination angle, cylinder radius, Darcy number, nanofluid concentration vary in the ranges of 0 to 100, 1 to 10, -5 to 5, 0.01 to 100, 0° to 90°, 0.2 to 0.4, 10−5 to 10−1 and 0 to 0.1, respectively. While the convection heat transfer coefficient is considered constant at (h = 5). It was found that, the vertical magnetic field decreases the stream function values more than the inclined and the horizontal fields. Also, the inclination angle of the magnetic field has a profound influence on the thermal performance inside the enclosure. The average Nusselt number rises by raising the Hartmann number, thermal conductivity ratio, cylinder radius and Darcy number, while it decreases by increasing the Richardson number. It was found also that, when the cylinder rotates in a counter clockwise direction (i.e., Ω = 5) and (Kr = 10), the Nuave decreases by about (90 %) when the (Ri) increases from 0.01 to 100. While, it increase by about (35 %) when the (Ha) increases from 0 to 100.

Kepulauan Seribu is a group of islands located in the north of Jakarta. which consist of several sensitive areas such as National Marine Park. settlement. coral reefs. fisheries. and tourism areas. The activities of oil & gas industries and shipping lanes in Kepulauan Seribu could potentially lead to oil spill pollution to waters and coast of Kepulauan Seribu which causing damage to sensitive areas. Past incidents of oil spills in Kepulauan Seribu has causing damages to fisheries. corals reef. and tourism activities. Therefore. appropriate oil spill preparedness and response are required since they are they are regulated by government and are important measures to minimize the negative impacts of an oil spill.

In developing country production environment, farm production efficiency is often measured in terms of on-farm resources and producer characteristics. In this paper we postulate that input and output market related factors also influence farm production decisions hence its efficiency. Stochastic frontier production function was used to assess technical efficiency and its determinants including input and output market variables for a sample of 1962 pig farms in Vietnam with data collected in 1999. There are significant differences in production behavior and efficiency level between the North and the South, among farms producing different breeds, between mixed and specialized farms, between household and commercial farms, and among producers located in different agro-ecological regions. Access to better output market, land size, herd size, and education of household head significantly reduced inefficiency, while access to government supplied inputs, age of household head, female headed households and family supplied crude feeds significantly increased inefficiency in both the regions. The direction of influence on efficiency differs between the two regions for access to credit, proportion of output sold at market rather than at farm gate and family labor supply. Generally, market related factors had more consistent influence on production efficiency in the South of Vietnam where the experience of market economics is longer compared to the North. Policy actions on providing better extension, more timely access to better quality inputs through the private sector, making credit more easily accessible to smallholders and opportunity to sell output at better priced secondary markets are expected to increase productivity and reduce inefficiency.

In this paper, the hypothesis that performance of trading firms depends on their assets (physical, financial, human capital and social capital) and trading practices is tested with data from a sample of 131 live animal traders in 38 rural Ethiopian highland markets. Most traders used own capital as access to credit, especially formal credit, was limited. The livestock market was characterised by non-standardised products and lack of information in the public domain about supply, demand and prices. Consequently, livestock trading was largely a personalised business though brokers and regular buyers and sellers, a form of social capital, were sometimes used for gathering information, searching buyers/sellers, price negotiation and contract enforcement. Business relationships with these intermediaries were principally based on trust, without strong ethnic, religious or family ties. Although most transactions were conducted in the physical presence of parties, contract violations were common, which were settled mainly through informal means as formal legal systems were either absent or time-consuming. Estimated costs and margins of most recent transactions showed low returns, and losses in some cases. Market levies, transport, travel and feeds were major items of variable cost, with some variation between cattle and small ruminants. Multiple regression analysis showed that traders' financial and human capital and trading practices such as use of brokers and regular suppliers and customers had varying effects on margins and costs of cattle and small ruminant trade. Unstable price, multiple taxes, non-transparent tax system, limited access to credit and weak demand for the quality of the products traded were perceived by traders as major problems of marketing. All the problems were amenable to public policy to improve the market environment and marketing efficiency. Copyright 2008 The author 2008. Published by Oxford University Press on behalf of the Centre for the Study of African Economies. All rights reserved. For permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.

World agriculture is based on a small number of animal species and a decreasing number of breeds within each species. Several breeds of West African shorthorn cattle ( Bos taurus brachyceros) are now at high risk of extinction due to interbreeding. The West African shorthorn breeds are particularly important resources because of their superior abilities to resist diseases, particularly trypanosomosis, and be productive under high humidity, heat stress, water restriction and with poor quality feed. An analysis of farmers' breeding practices and breed preferences in a sample area in southwest Nigeria confirmed a strong trend away from trypanotolerant breeds, especially Muturu, and identified the traits farmers find least desirable in these breeds relative to zebu ( Bos indicus ) breeds. An analysis of cattle market prices found that buyers have preferences for specific breeds for specific purposes and that though in general price differences due to breed are small, in some cases, buyers pay significantly different prices for certain breeds consistent with their preferences. The best hopes for increased utilization of breeds at risk such as Muturu is likely in other areas of West Africa, for example in southeast Nigeria, where the Muturu is better suited to the farming systems and there is a large market for this breed to provide incentives.

It is argued that information on farmer knowledge about characteristics, adaptability and management needs of different species and breeds of domestic animals, and farmer preferences about these traits are useful inputs in designing breeding policy and conservation strategy. The argument is reinforced with several examples. At present, animals meet about 30%t of human requirements for food and agriculture. About 40% of the total land available in developing countries can be used only for some form of forage production and about 12% of the world's population live in areas where people depend almost entirely on products obtained from ruminant livestock. Animal genetic diversity is essential to sustain the productivity of agriculture and the livelihood of people. Ever increasing loss of animal genetic diversity erodes our capacity to maintain and enhance livestock production, productivity and sustainable agriculture. It reduces the ability to respond to changing conditions. In this paper, we will enumerate some of the reasons for the loss of animal genetic diversity, the arguments for conservation, and the role that farmer knowledge and preferences can play in developing strategy for breeding policy and coservation. Reasons for loss of diversity Genetic diversity is being lost because of human activity and changes in production systems, people's preferences and attitudes, market conditions, and opportunities. Some of the specific reasons for the loss of genetic diversity are

World agriculture is based on a small number of animal species and a decreasing number of breeds within each species. Several breeds of West African shorthorn cattle (Bos taurus brachyceros) are now at high risk of extinction due to interbreeding. The West African shorthorn breeds are particularly important resources because of their superior abilities to resist diseases, particularly trypanosomosis, and be productive under high humidity, heat stress, water restriction and with poor quality feed. A study was undertaken in the derived savanna area of southwest Nigeria to determine the prospects for conservation through use and possible improvement of the Muturu, a West African shorthorn breed known to be in decline throughout southern Nigeria. An analysis of farmers’ breeding practices and breed preferences confirmed a strong trend away from Muturu and identified the traits farmers find least desirable about the Muturu relative to other breeds. An analysis of cattle market prices found small, but significant, price differences by breed. The best hopes for increased utilization likely in other areas of West Africa, such as southeast Nigeria, where the Muturu is better suited to the farming systems and there is a large market for this breed.

A survey of two rural markets in southwest Nigeria over 14 months showed that supplies, sales and prices of sheep and goats varied widely during the period with a sharp peak during the Muslim festival of Eid-el-Kabir and a smaller peak during the Christmas-New Year period. Local West African Dwarf (WAD) sheep and goats and northern Y'ankasa sheep and Red Sokoto goats were traded in the markets and animals were purchased for rearing, trading, ceremonies, butchering/catering, sacrifice, and festivals. There were significant differences between species/breeds purchased for various purposes. A hedonic price model was fitted to determine factors influencing price. After adjustments were made for age, weight, sex, time of transaction and market, WAD sheep commanded higher prices than WAD goats and Red Sokoto goats for all purposes except for butchering/catering; Red Sokoto goats commanded similar or lower prices than WAD goats depending on the purpose for purchase; and Y'ankasa sheep, principally purchased for the Eid-el-Kabir festival, commanded marginally higher prices than WAD sheep. The market share of WAD sheep is currently small and is under competition from northern sheep and goats, so increased production of WAD sheep in the south will benefit both producers and consumers in the area. In general, the results indicate that buyers have preferences for specific breeds and species for specific purposes, so producers and sellers may benefit by targeting specific buyer categories and times of the year.

The moist savannah zone in sub-Saharan Africa is regarded as a high potential area for crop and livestock production. Currently, human labour is the principal source of power for crop production and the level of commercial energy use is very low. Agropastoralism and pastoralism are the principal methods of livestock production. Crop-livestock mixed farming, in which manure and animal power are important energy sources in the production process, is only now emerging. The integration of crops and livestock and the implications for agricultural energy sources are related to population pressure and labour intensity, the intensification of crop production with and without livestock, the role of traction in general and in specific niches, the contribution of livestock to the development process in terms of food or other inputs, and the role of public policy and intervention in development.

In this study subsidies are treated as both an element of government expenditure and a source of household income. The impacts of reallocating existing subsidy expenditure to selected alternatives are estimated upon factors such as growth, employment, personal saving indirect tax and import using a semi-closed input-output model. The results indicate substantial scope for deriving additional benefits by reallocating the existing subsidies on foreign wage earnings and urban food ration (enjoyed by the richer classes) to fertilizer, foodgrain procurement or rural food rations (enjoyed by the poorer classes). Reallocation of fertilizer or rural food ration subsidies have no benefits. The benefits of reallocation to production activities are higher than for consumption activities.

Stochastic frontier production function was used to assess technical efficiency and its determinants for a stratified sample of 1118 poultry farms in Vietnam for which data were collected in 1999. In general there are significant differences in the production behaviour and efficiency level between the North and the South, among farms producing different breeds of poultry, between mixed and specialized poultry farms, between household and commercial farms, and among producers located in different agro-ecological regions. Sale at market place rather than at farm gate, market distance and flock size significantly reduced inefficiency in both the regions. Contract farming or sale, number of visits by extension staff, family labor supply, land size and education of household had significantly reduced inefficiency in the North but had no significant effect in the South. The direction and significance of influence on efficiency differ between the two regions for credit use, inputs from government, ratio of home produced of crude feed, producer age and gender of household head. Therefore, opportunities exist for improving average efficiency through interventions in a number of product and input market domains and household characteristics that may improve access to information, technology and management decisions.

Hedonic price models were fitted to a sample of 1397 sheep and 1293 goats respectively for which data were collected from nine markets in Ethiopia over a 12 month period. The objective was to determine seasonal and inter-market differences in prices after controlling for the effects of different attributes of the animals, the buyers and the sellers. Results indicate that, controlling for attributes of the animals and of the buyers and sellers, there were significant differences in prices between seasons and markets. Seasons in which farmers faced severe cash shortages exhibited the lowest adjusted prices for animals they sold, indicating that although livestock may provide a fall back position for cash in times of crisis, terms of trade may be worst when farmers need cash the most. In general, there was no clear progression in price of sheep along the primary to terminal market chain ending in Addis Ababa as would be normally expected except that the farthest market had the lowest price. The reason for higher prices in some intermediate terminal markets could be partly explained by the fact that exporters and processors buy animals in these markets and they pay premium prices for best quality animals, and left over second or third grade animals may end up in Addis Ababa market, which then virtually becomes a sink market. In case of goats, price differences between markets followed to some extent the expected differences between primary, secondary and terminal markets. One possible reason is that in general highland is not a major production or consumption area for goats, so supplies come mainly from the lowlands, so the price movement followed the market chain from primary markets in pastoral areas to the terminal market in Addis Ababa,.

This article tests the hypothesis that anthropometrical outcomes in preschool children are a function of complex interaction between food, nutrition, health, and other physical environmental conditions within which children live and grow. A system of simultaneous equations is used to test the above hypothesis using data from an Ethiopian highland community. The results show that a child's nutritional and health status are jointly determined by dietary intake, well-being of the mother as the primary caregiver, and the state of the physical environment for agricultural production and healthy living. Among other factors, children were found to be in better health with an increase in the number of cows in their households’ livestock herds. The revealed interrelatedness and complexities of cause and effect clearly dictate the need for a multi- or transdisciplinary approach to research and development addressing health, nutrition, sanitation, agricultural production practices, among other factors for alleviatin...

Agricultural intensification in West Africa is at an early stage and the process is taking place through various pathways. Population pressure and market access are generally considered as major factors driving intensification and crop-livestock interaction. In this paper both ecology and economic factors and their interactions are hypothesized as driving forces in intensification and crop-livestock interaction. Analyses of a survey involving farming households in Nigeria confirm the hypothesis and show that the degree of intensification is higher in the Sudan savanna than the Northern Guinea savanna. Intensification is occurring mostly through higher land and labor use intensity, higher livestock stocking rates and application of more manure per hectare. It is concluded that policies to enhance market access will facilitate the process and that different technological options need to be pursued in the two agroecological zones to facilitate intensification.

Farmer participatory tillage trials were conducted in a highland Vertisol area of Ethiopia during the 1999 and 2000 cropping seasons. This participatory initiative clearly demonstrated that incorporating farmers’ knowledge, ideas and preferences could improve the wheat production package. A traditional practice of Chefe Donsa farmers—applying ash from their homesteads to their fields to enable early-sown crops to withstand frost—led to the verification of the yield-enhancing effect of inorganic potassium fertilizer on wheat. Farmer adoption of a minimum tillage production system increased the gross margin of wheat production by US$ 132 per hectare—based on 1999 prices—relative to the traditional flat seedbed system. The minimum tillage system was characterized by a much lower level of soil manipulation relative to the traditional flat seedbed system, and, as a consequence, markedly reduced the total human labor and draft oxen requirements for wheat production. Thus, the minimum tillage system could be an effective intervention for soil conservation due to early-season vegetative cover of the soil surface. Also, the early crop harvest associated with the minimum tillage system was highly beneficial for small-holder farmers—since the early harvest coincided with the cyclical period of severe household food deficits and high grain prices in local markets.

World agriculture is based on a small number of animal species and a decreasing number of breeds within each species. Several breeds of West African shorthorn cattle (Bos taurus brachyceros) are now at high risk of extinction due to interbreeding. The West African shorthorn breeds are particularly important resources because of their superior abilities to resist diseases, particularly trypanosomosis, and be productive under high humidity, heat stress, water restriction and with poor quality feed. An analysis of farmers’ breeding practices and breed preferences in a sample area in southwest Nigeria confirmed a strong trend away from trypanotolerant breeds, especially Muturu, and identified the traits farmers find least desirable in these breeds relative to zebu (Bos indicus ) breeds. An analysis of cattle market prices found that buyers have preferences for specific breeds for specific purposes and that though in general price differences due to breed are small, in some cases, buyers pay significantly different prices for certain breeds consistent with their preferences. The best hopes for increased utilization of breeds at risk such as Muturu is likely in other areas of West Africa, for example in southeast Nigeria, where the Muturu is better suited to the farming systems and there is a large market for this breed to provide incentives

Based on analysis of credit supply in Ethiopia, Kenya, Uganda and Nigeria, it is shown that public credit institutions do not have sufficient funds to meet the demand for livestock credit and cannot mobilize savings from their clients or other commercial sources for one reason or another. In addition, available credit does not reach those who need it the most and with whom it could have the greatest impact due to the application of inappropriate screening procedures and criteria to determine creditworthiness. The analysis of demand based on borrowing and nonborrowing sample households using improved dairy technology, it is shown that not all borrowers borrowed due to liquidity constraint while some borrowers and some nonborrowers had liquidity constraint but did not have access to adequate credit. Logistic regression analysis show that sex and education of the household head, training in dairy, prevalence of outstanding loan and the number of improved cattle on the farm had significant influence on both borrowing and liquidity status of a household, though the degree and direction of influence were not always the same in each study country. Based on the findings it is suggested that combining public and commercial finance could solve the problem of inadequate credit supply while inventory finance to community level input suppliers and service providers might help in getting credit to worthy and needy smallholders at lower cost than providing credit to smallholders directly.

The main aim of land preparation is to modify and manipulate the land features so as to create favorable environment for seed establishment and crop growth. The research and development in this field must take into account the traditional practices used by the farming community. This paper gives a brief description of farmers’ management of Vertisols and soils with 'vertic' properties and the development of the low cost broadbed maker (BBM) for facilitating surface drainage. Other attachments like planters and cultivators to the BBM for minimum tillage system which are going to be tested on-farm are also discussed.

The Multi-purpose Tree (MPT) species have the ability to fit into the farming systems of the East African region where low agricultural productivity, widespread land degradation and hence a diminishing capacity to support the growing human and livestock population are major problems. GIS has been used to develop a spatial representation of the recommendation domains of five MPT species (Calliandra calothyrsus, Sesbania sesban, Leucaena diversifolia, L. pallida and Chamaecytisus palmensis) in Ethiopia, Kenya and Uganda. The recommendation domains were selected based on climatic, edaphic and topographic factors. The likelihood of adoption, within the agro-ecologically suitable areas for each species, has been defined by weighing and combining three factors: the type of land cover/land use, the human and cattle population densities.

Vertisols are important underutilized resources in the East African highlands because of their inherent waterlogging problem. In this paper, group experience in the design, development and diffusion of a technology package through farmer participation for improving management and productivity of Vertisols is described. The results indicate that farmer knowledge, capacity and incentives are important considerations at every step in technology generation and diffusion. Results also indicate that technology adoption is not a one-off decision rather farmers move from acquisition of knowledge to adoption to continuous or discontinuous use. The set of factors influencing each decision may be also different. The experience also indicates that for effective use of technologies that are complex and may create externality, household level decisions are not adequate, rather involvement of the community in watershed or landscape management may be required. Participation of individual households in such collective action for common resource management is most likely to be influenced by the potential benefit to the participants. The experience of the project also indicates that introduction of component technologies and other interventions in a haphazard manner may not lead to sustained improvement in productivity and human welfare and maintenance of the ecosystem. An integrated and holistic approach incorporating biophysical, economic and social dimensions of any ecosystem is more appropriate for achieving those goals. Background Highlands (1500 masl) cover about 10% of tropical Africa, mostly located in the East Africa region, but they support close to half the human and about 30% of the total livestock populations. Major problems encountered in the highlands of this region are poverty and malnutrition, low crop and livestock productivity, widespread land degradation, and underutilization of some resources due to specific constraints The highlands of Ethiopia make up over 60% of the East African highlands and account for more than 80% of the agricultural lands. In addition, they serve as the major catchment for many tributaries that feed the river Nile. The majority of agricultural production is in the hands of the peasant sector, and farm technology has undergone little change for hundreds of years. As in other countries in the region, the smallholder farmers in the Ethiopian highlands are poor, individual land holdings are no more than 0.5 to 2.5 ha, family sizes are large, land productivity is low; thus food requirements are not met. Deforestation is common, steepslope cultivation and over grazing have become rampant in response to the increasing

Previous farm-level studies have shown that adopting improved feeding and management strategies improves livestock productivity and, in particular, increases the milk production and income of resource-poor smallholder mixed-crop and livestock farmers. This paper analyses the impact of the introduction of crossbred cow and improved feeding and management technologies in the Ethiopian highlands in terms of direct changes in household income, patterns of food and non-food expenditure, and caloric intake. Using a recursive econometric model that takes into account the seasonal variability of consumption patterns, the analysis indicates a positive relationship between household income and adoption of the improved dairy technologies. The incremental increase in household income translates directly into higher expenditure on food and non-food items. Caloric intake is also positively related to adoption of crossbred cows and improved feed technologies. This indicates the significant role that improved smallholder livestock technologies can play in improving food security and nutrition as well as alleviating poverty.

The aim of this study was to assess the process and extent of sedentarisation among Fulani cattle owners in the derived savannah zone of south-west Nigeria. The results, based on a survey of 66 randomly-selected cattle owners, indicate an on-going process of settlement. Previously cattle owners visited the zone for dry season grazing but an increasing number were found to be settling and becoming mixed livestock/crop farmers. Generally herd sizes were larger among recent settlers but with longer duration of settlement and with cattle rearers' involvement in crop production, the herds became less mobile between seasons and herd size decreased and the proportion of farms with mixed zebu/trypanotolerant cattle herds increased. There was also evidence that some indigenous Yoruba crop farmers were becoming mixed farmers by purchasing cattle, hiring Fulani herdsmen for management, then taking up the management themselves.

The incorporation of livestock into alley farming systems, in which food or forage crops are grown between hedges of multipurpose trees that are regularly pruned for mulch and/or forage, has been studied for over 10 years in Africa. Prunings from leguminous trees such as Leucaena and Gliricidia can be used for mulch, increasing crop yields, but the trees may also be pruned for fodder, especially during fallow periods. The major benefit from supplementing the diet of free-roaming small ruminants in West Africa with the foliage of leguminous trees is increased survival, and the forage is best directed at late pregnant and lactating females. In East Africa crossbred dairy cows show a significant response in milk production to supplementation with Leucaena. Economic analyses of livestock production show that continuous alley farming is more profitable than alley farming with fallow, or conventional no-tree farming, even when the cost of clearing trees at the end of their useful life is included.

Cattle rearing in humid west Africa was nearly impossible in the past owing to the prevalence of trypanosomiasis, a disease caused by the tsetse fly. However, in recent times, with population pressure, jungle clearance, crop cultivation and tsetse control measures, the challenge has been reduced. Consequently there has been an influx of transhumant cattle rearers who used to visit the zone for dry season grazing and return to the safer sub-humid and semiarid zones in the wet season. An increasing number of them have begun to settle in the humid zone and are adopting crop-livestock mixed farming. There is also a tendency among some local crop farmers to adopt livestock in the farming systems. Consequently new farming systems are evolving in the zone. The potential of this evolving farming system and its implications for systems oriented research by national and international centres are examined.

(1988). The limitations of cross‐breeding for improvement of cattle in Bangladesh. Oxford Agrarian Studies: Vol. 17, No. 1, pp. 29-56.

The problem of treating management as an explanatory variable in agricultural production function has not yet been solved satisfactorily mainly because of the lack of a generally accepted cardinal measure. Only a few agricultural production function analyses are known to have included management as an explanatory variable. These investigations have specified management in different ways under a diversity of assumptions and obtained different kinds of results even with comparable situations. The objective of this article is to present a critical review of the theoretical meaning of management and of the effectiveness of different ways of treating management in empirical investigations. I The term management is conventionally considered as consisting of two parts: coordination or entrepreneurship and supervision. The existence of the firm as a decision making unit and the need for co-ordination grows out of dynamic situations, changes in factor and product prices, and other uncertainties. Important steps in co-ordination include expectation about the future, plans, action, and acceptance of consequences. If everything were known with certainty, the firm as an entity would not arise and there would be no need for co-ordination although production would still take place. Once the basic decisions about production are made, the managerial activity reduces to routine management or supervision. Therefore, co-ordination or strategic management may be taken as true management (4, pp. 67-8; 12, pp. 465-7; 19, pp. 386-405). Practically, it may be difficult to distinguish clearly between co-ordination and supervision but, theoretically, from Marshall’s (21, pp. 618-24) classification of profits as consisting of two parts: normal profits or wages of routine management which enters into long-run supply price, and extraordinary profits, it follows that the premium for co-ordination or risk taking is in reality a ‘quasi rent’ or ‘producer’s surplus due to rare natural qualities.