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The internet makes it easier for buyers to purchase goods from distant sellers. However, the inability of the buyer to examine the merchandise results in asymmetry of information. This paper develops a the oretical model to analyze the relationship between quality and price in a setting of asymmetrical infor mation. In the spirit of Akerlof (1970), the model predicts that higher quality goods are less likely to be sold in the market. Since buyers have difficulty distinguishing quality, sellers would have to accept lower prices for their highest quality items. The model is tested using data from internet coin auctions.The results show that coins that are claimed to be of higher quality are less likely to sell and when they do sell do so at lower prices relative to their market value.

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In 1937, Hallock and Benson demonstrated a progressive loss of aortic distensibility with aging (1). Their observations on the pressure-volume relationship in segments of human aortas from five age groups are shown in Figure 1. The curves which represent the less distensible older aortas have a greater slope (d P/d V). The slope of each curve is not fixed, however, and it changes by bending toward the pressure axis as pressure increases. The rate of this change in slope (or the curvature) also is greater in the curves of older aortas.The present report deals with an indirect clinical index of the curvature of arterial pressurevolume curves, using the ratio of the change in pulse pressure to the change in diastolic pressure following the inhalation of amyl nitrite. This index is referred to, arbitrarily, as one of "arterial rigidity." A study of Hallock and Benson's curves made it apparent to us that the change in the slope of each curve is associated with a corresponding change in pulse pressure at different diastolic pressures. If the pressure-volume curve is relatively straight, as it is in the young, the curvature and the index will be near zero (Figure 2). If the line curves greatly toward the pressure axis, the index will be positive and large (Figure 3). If it curves the other way, the index will be negative. In vitro indices were derived from each of the five aortic distensibility curves and were found to correlate with age ( Figure 4). This observation suggested that the values of this index in "normal" subjects also should increase with chronological age. MATERIALS AND METHODSSelection of subjects. The subjects for this investigation were patients from the wards and members of the professional staff of Milwaukee County Hospital. One hundred fifteen subj ects varying from 8 to 95 years of age were studied. They were separated into nine age groups. Seven subjects, aged 8 to 19 years, comprised the first group; 4 subjects were 20 to 29 years of age; 18 were 30 to 39 years; 24 were 40 to 49 years; 21 were 50 to 59 years; 13 were 60 to 69 years; 16 were 70 to 79 years; 9 were 80 to 89 years; and 3 were 90 to 95 years. A careful clinical examination and review of the hospital records disclosed normal retinal vessels,1 "normal" blood pressures 2 and freedom from heart disease, overt periph- 1 Silver wiring and tortuosity were accepted as normal retinal changes in subjects over 60 years of age.2 All the subjects under 60 years of age had blood pressures below 140/80 and all those over 60 years had blood pressures below 170/90. 933

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Although the count of circulating lymphocytes in the blood stream remains constant, more lymphocytes enter the blood from the thoracic duct during 24 hours than are present in the blood at any one time. This excess of lymphocytes is not destroyed in the blood stream. The cells migrate from the blood vessels into the mucous membranes and through them to their surface. This occurs chiefly in the gastrointestinal tract, and it is apparently in the mucosa and especially within the intestinal lumen that the function of the lymphocyte is normally performed.