A perfused organ should provide a useful tool for metabolic studies, especially for investigation of the significance in the metabolism of the whole organ of reactions known to occur in broken cell preparations. Perfusion of rat livers with saline solution through the vena cava has confirmed the importance ofpyruvate in transamination reactions (Bristow & Kerly, 1964) (1951). Unfortunately not only do Miller and his co-workers give insufficient information on some important experimental points (e.g. the method of filming the blood in the oxygenator), but they have varied the conditions, such as the composition of the perfusion medium, from one set of experiments to another. Other authors have introduced modifications so that experimental conditions have varied considerably and few studies, even from the same laboratory, are strictly comparable. Therefore before attempting a study of amino acid metabolism in livers perfused with blood it was necessary to develop a standard technique which would allow the liver to be maintained as nearly as possible in a normal physiological condition for several hours and then to investigate changes in amino acid composition of liver, perfusion medium and bile under basal conditions. The results of this investigation are described below.

for the acetonedried powder of Nicotiana tabacum.

IN the course of an investigation on glycogen, the solubility of a sample prepared in the usual way by boiling tissue with 60 % KOH was compared with that of a sample prepared from an aqueous extract of tissue dehydrated by alcohol, and it was observed that the former sample reached a stable value very much more rapidly than the latter. It was therefore decided to prepare glycogen from several sources, without boiling with potassium hydroxide and to determine the solubilities of the products obtained. In the course of the work it was found necessary to revise the method employed for estimating glycogen, and, in order to do this, the solubility of glycogen in aqueous alcohol was investigated.

uterus has been shown to vary with the phase of the oestrous cycle. Raab [1929], working with human uterine mucosa, found variations in metabolism with the phase in the menstrual cycle, but Adler [1930] was unable to confirm these results. Victor et al. [1936] have shown that the respiration rate of rat-liver slices is increased during oestrus, whereas kidney slices from the same animals showed no cyclic changes. Victor & Andersen [1936], working with anterior pituitary gland (from rats), found respiration and anaerobic glycolysis to be higher during the pro-oestrous and oestrous phases of the cycle, but they were not able to show significant changes in aerobic glycolysis.The experiments presented here show that the anaerobic glycolysis of isolated rat uterus also varies similarly to the respiration, and that aerobic glycolysis varies, but in the opposite sense to respiration and anaerobic glycolysis.

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