THE influence of the temperature upon the dissociation curve of oxyhaemoglobin has been investigated by Barcroft and A. V. Hill(1), and their results are summarised in the curves given by Bar croft (2), which show that the rectangular hyperbolas, which represent the relation between oxygen tension and percentage saturation with 02 of a solution of haemoglobin, are much increased in steepness by decreasing temperature. The relations between the temperature and the dissociation curves of Hb as determined by Barcroft and Hill are given by the formulee ,I Tta -T, Kx~~~~~T .2 T,(1) 1-O=I+K and (2) Ke2 12T 10 +Kx~Ke of which the first is the equation of a hyperbolic dissociation curve and the second expresses the relations of the constants of two dissociation curves valid at the absolute temperatures T2 and T1. In (1) y is the percentage saturation of the Hb with oxygen and x the oxygen pressure in mm. Hg. In (2) q is the heat evolved when one gram-molecule of oxygen combines with one gram-molecule of Hb. q has been determined by Barcroft and Hill as 28,000 gram calories and shown to be constant over a range of temperatures from 160 to 49°. In the following we have assumed it to be -constant also below 160. Barcroft and Roberts(3) determined the value of K at 380 as 0*125. From these data a curve for the dissociation of oxyhsemoglobin can be calculated for any temperature.Each hyperbola is characterised by the value of K. We have found it much more convenient however to use R as a characteristic, since it can be easily shown that k corresponds to the 02 pressure at which the Hb is just half saturated with oxygen'. This 02 pressure we denote as the We have at the point of half saturation y =50 and hence from (1) 50Kx 1 100 = 1-+-Ex or x =

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THE study of iodine metabolism has been retarded by the technical difficulty of estimating accurately the small amounts of iodine which occur in foodstuffs and in tissues and body fluids. Kendall's method [1914, 1920], which is that most widely used at the present time, is admirably suited for the analysis of thyroid tissue, which contains roughly from 0-01 g. % to 0 5 g. % of iodine, and, as modified by Kelly and Husband [1924], it is in routine use at this Institute for that purpose. The method has, however, a lower limit of detectable iodine of 5y (y = 0-000001 g.). For the estimation of iodine in human blood, therefore, Kendall required 100 cc., since the content is only 13 y %. The method is

AberdeenshireIt seems to me sometimes that famous dicta of famous men, if repeated often enough, have the unfortunate effect of sterilizing thought instead of enlivening it. For instance the dictum of Claude Bernard that 'La fixit6 du milieu interieur c'est la condition de la vie libre', by focusing the attention of physiologists and biochemists on the static aspect of the composition of bodies, and on physiological devices and dietary requirements to maintain the static equilibrium, may have contributed to a somewhat rigid attitude of mind. So many are still reluctant to recognize that the equilibrium of the milieu intirieur may be set at different levels in the same organism and they continue to regard as pathological much of the amazing range of variation that is, in fact, compatible with healthy life. Pregnancy offers an outstanding example of this. Twenty years agoWhen Garry & Stiven (1935-6) wrote the first review of metabolism in pregnancy for Nutrition Abstracts and Reviews, 20 years ago, it was customary to assess the normality of the pregnant woman, for instance in respect of composition of the blood and basal metabolic rate, by comparison with accepted standards for non-pregnant women, and inquiries about diet were concerned with how much extra protein or calcium or iron the pregnant woman might require to supply the foetus and additional maternal tissues. And this attitude persisted although it had already been demonstrated that, on any ordinary diet in this country or America, the pregnant woman stored nitrogen and structural minerals in amounts far in excess of those in foetus and maternal accessory tissues. 'The diagnosis of anaemia' the review says 'will depend on the "normal" standard adopted for non-pregnant women, which is difficult to define, since the range of variation is wide'. And, of course, a diagnosis of anaemia meant the prescription of iron.On the other hand, we have this pearl of wisdom following a review of studies of birth weight: 'Hence, it is possible that, under any but extreme conditions, the birth weight of the child depends less on the food intake of the mother than on its https://www.cambridge.org/core/terms. https://doi

Optimum Calcium Requirement SIR,-In sour issue of January 11 (p. 49) a paper by Dr. l. Harris and Messrs. J. T. Ireland and G. V. James is published in which the conclusions are drawn that "with a high degree of certainty it can be affirmed that the calcium intake under the present dietary regime is ample" and that there is no indication for increasing it. In addition the suggestions are made that high calcium intake may be a contributing cause of arteriosclerosis and that it seriously increases the work of the kidney. These conclusions and suggestions are so unusual and so important, if established, that the evidence requires