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Phosphate plays a role in a number of body functions: calcium phosphat'e is a prominent constituent of skeletal structures; organic phosphate complexes are of importance in energy transformations within cells; and, as the chief buffer component of the urine, inorganic phosphate aids the body in balancing its acid base requirements. Since the urine is the major portal of exit for excess phosphate of dietary origin, the renal mechanisms controlling loss or conservation of the body's stores of inorganic phosphate are of prime interest. Recent investigators (2, 7, 12, 19, 22) concede that phosphate is filtered through the glomeruli, a part is reabsorbed by the renal tubules and the excess is excreted. Upon the characteristics of the reabsorptive process, which fundamentally determine the balance between conservation and elimination, there is less agreement. Harrison and Harrison (7) claim that the capacity of the renal tubules to reabsorb phosphate is limited in the same sense as Shannon and Fisher (16) had previously shown glucose reabsorption to be limited. Thus, if phosphat'e is presented to t,he renal tubules in the glomerular filtrate in amounts exceeding their capacity to reabsorb, the excess appears in the urine. The limited range of plasma phosphate concentration in their studies, i.e., from 3 to 10 mgm. of phosphate phosphorus per 100 cc., is insufficient to establish their conclusion definitely. Smith, Ollayos and Winkler (19) reinvestigated the problem and arrived at the opposite conclusion, namely: that the capacity of the tubules to reabsorb phosphate increases progressively with increasing plasma concentration over a range from 3 to 40 mgm. per 100 cc. Their experiments were complicated by rapid falls in plasma concentration and by sharply declining rates of glomerular filtration. Coupled with their few experiments, these factors render their conclusion unconvincing. As a preliminary to a study of the renal mechanisms for the regulation of acid base balance, we have found it necessary to determine the properties of the renal tubular reabsorptive mechanism for phosphate. Our results indicate that the capacity of the renal tubules to reabsorb inorganic phosphate is limited and that the mechanism is relatively st,able and unaffected by considerable shifts in electrolyte and acid base balance of the organism. METHODS. Our experiments have been carried out on 5 trained female dogs loosely restrained on a comfortable animal board. Water, in amounts of 50 cc. per kilo, was administered by stomach tube at the start of the experiment to ensure adequate hydration of the animal. Urines were collected by catheter and the bladder washed out with distilled water at the end of each 10 minute 648

This article revisits the question of voter turnout in American presidential elections from the perspective of political generations. We extend previous analyses by examining the entire period between 1952 and 1996 by further specifying the turnout model and, most important, by incorporating a generational component. We hypothesize that the direct effect of membership in the cohort born prior to 1932 is to increase voter turnout and the indirect effect of membership in this cohort is to increase the impact of party-related variables in accounting for turnout. Finally, we hypothesize that the indirect effect of membership in the cohort born after 1932 is to increase the impact of socioeconomic, media-related, and candidate-related variables. Our findings strongly suggest that generational effects account for a significant component of the decrease in turnout among American citizens. The impact of generations is most pronounced in the first half of the voting life cycle.In Democracy in America, Alexis de Tocqueville alluded to the difference between a subject and a citizen. The former passively allows the government to initiate and carry out public policy; the latter actively participates in the rituals of democracy. In many ways the legitimacy of a democratic polity can be cast as a function of the ratio of citizens to subjects. It would seem that a relatively obvious sine qua non of citizenship is voting. Applying this admittedly minimalist view of citizenship to American presidential elections, the citizen0 subject ratio is now in the neighborhood of unity. While the polity may not be in danger, it may well be in need of some introspection. Why are more and more of us not voting?Americans have long voted at a relatively low level. This level declined over the last half of the twentieth century, reaching 49% of those eligible in the 1996 presidential election. This decline has been difficult to explain in the context of an electorate seemingly better prepared to participate. Brody's (1978) prescient observation that the decline in voter turnout had occurred in the face of increased education generated a voluminous amount of scholarship by those attempting to solve the "puzzle of participation" (see Abramson and Aldrich 1982;

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In dogs anesthetized with chloralose, innervated loops of intestine were isolated so as to permit periodic interruptions of blood flow to record pressure-volume diagrams from the venous bed. Pressor reflexes were found to produce alterations in the venous distensibility diagrams which, on the basis of comparison with distensibility changes produced by constrictor drugs, are interpreted as direct evidence of venoconstriction accompanying pressor responses of the cardiovascular system. I NVESTIGATIONS of the functional role of the venomotor system have been handicapped by the lack of an adequate method for assessing its activity. Changes in the caliber of veins have been observed under various conditions, 1 but this is not adequate evidence of venomotor function unless these observations are correlated with an analysis of the associated hemodynamic factors. In the over-all regulation of the cardiovascular system, however, indirect evidence justifies the inference that there must be an important venomotor contribution to circulatory homeostasis, in addition to the well demonstrated adjustments of cardiac output and arteriole resistance. • 3Opportunities for a direct attack on this problem have been developed from studies of the distensibility of the splanchnic venous system 4 and the analysis of the influence of constrictor drugs on this distensibility.5 Such distensibility determinations appear more relevant to the problem of venomotor activity than would flow resistance studies of the type employed in assessing arteriolar constriction, since A'enous capacity is a more significant variable than is venous resistance to blood flow. 6 The following observations on splanchnic venous distensibility in anesthetized dogs demonstrate directly the constriction of venous elements as part of the response observed in the common pressor reflexes.From the Department of Physiology, Medical College of Georgia, Augusta, Ga.This investigation was supported by grunts from the National Heart Institute, U. S. P. II. S., and from the Life Insurance Medical Research .Fund.Received for publication April 26, 1954. METHODSAs described previously, 5 the physical characteristics of the splanchnic venous system demand rigorously controlled rates of distension and exact intervals between measurements if comparable distensibility determinations are to be obtained. This has been achieved in these experiments by injecting blood into the venous system of intestinal loops at the rate of 50 <:c. per minute by means of a motor-driven syringe, all injections being spaced accurately at JO-minute intervals for both control and experimental observations. The injection procedure described below required less than 30 seconds; for the remainder of the 10-minute interval between injections, perfusion of the loop was maintained by the dog at its existing arterial blood pressure.To preserve the sensitivity of cardiovascular reflexes, the dogs were anesthetized with chloralose following morphine sedation, employing 75 ing. of chloralose per kilogram for inducti...