In all determinations of the circulating plasma volume by dye methods, it is. necessary to allow sufficient time to elapse for complete mixing of the dye with the plasma before withdrawing a sample for estimation of the concentration. During the mixing period a certain amount of dye disappears from the circulation, and in order to try to arrive at a value for the mixing time and to determine the loss of dye during this period, dye-disappearance curves have been plotted.

The opinion is widely held that oatmeal may have a detrimental effect upon Ca absorption because of its high content of phytate-P. The only investigation undertaken specifically to study this effect in man is-that of Burton (1929-30), who compared absorptions and retentions of Ca and P in children and adults receiving wheat and oatmeal diets. This worker found better retentions of Ca when wheat diets were taken. The children were irradiated with ultraviolet light, and in four cases out of six the Ca absorptions and retentions were several times the normal values established by Duckworth & Warnock (1942). Further, the Ca intake was not equalized, so that in all subjects but one the Ca intake was greater on the wheat than on the oatmeal diet. Steggerda & Mitchell (1939), who incidentally used a basal diet rich in oatmeal to keep the Ca intake low, found Ca absorption and requirement within normal ranges. Since McCance & Widdowson (1935, 1942) found that, under their experimental conditions, adult man excreted approximately half the ingested phytate-P of wheaten flour and that the phytates seriously interfered with the absorption of dietary calcium, it appeared desirable to investigate the utilization of phytate-P in oatmeal at various levels of Ca intake. At the same time it was thought desirable to follow the balances of Ca and Fe. METHODS The general pattern of the diet was made to conform, as far as possible under the conditions of the experiment, with that found by Cathcart, Murray & Beveridge (1940) to prevail in the Scottish Highlands. To keep the Ca content of the diet low, cheese was eliminated and milk intake reduced. Since the oatmeal intake in the Highlands is lower today than hitherto, the allowance was increased to bring it closer to that consumed during last century (Hutchison, 1868). This led to a corresponding reduction in flour intake. To simplify the experimental procedure, to reduce the amount of analysis, and to minimize the variability of factors other than Ca intake, a constant diet was eaten throughout the study. This was made possible by the collaboration of the Low Temperature Research Station and the Torry Research Station, both of the Department of Scientific and Industrial Research, to whom our thanks are due for generous gifts of dehydrated foodstuffs and frozen fish.

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THE purpose of this research was to determine whether or not the heart in the absence of circulating carbohydrate would utilize added amino acids, and to secure further evidence for the direct oxidation of fat by the heart.That ammonia appears in muscle and in fluids by which muscle or organs have been perfused has been demonstrated by many [Warburg, Posner, and Negelein, 1924;Winterstein and Hirschberg, 1925;Embden, 1927;Embden and Schumacher, 1929; Lehnartz, 1929;and Clark, Gaddie and Stewart, 1931]. Meyerhof, Lohmann and Meier [1925] and Reinwein [1928] have stated that with good oxygenation sections of liver, in contrast to muscle, are capable of forming ammonia from amino acids. But when dead or dying tissue is used in thin sections one is confronted with the fact that other than living processes are at work. That the living kidney will produce ammonia has been demonstrated by Nash and Benedict [1921], Gottlieb [1928] and Embden and Schumacher [1929].The work of Krebs [1933] would go to show that the amino acids are deaminated not only in the liver but also in the kidney of the rat and that the formation of ammonia is 3-10 times greater from the non-naturally occurring amino acids than from the natural amino acids. Gyorgy and R6thler [1927] have shown that liver, kidney, thymus and muscle, as well as extracts of these tissues, are capable of forming ammonia from sodium nuclein (Merck) and adenosine under conditions in which for the liver the optimum pH is 5-2-5-5. They also state that, for several kinds of tissue, ammonia arises either from known amino acids by methods in a manner incompatible with the known laws of autolytic production of ammonia in tissues as by enzymes or, and this they regard as certainly unlikely, from protein, urea or by deamination of amino acids during PH. LXXXVI.

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