KAY [1930] showed that in certain bone diseases in man the plasma-phosphatase activity is considerably higher than normal. This served as an impetus for investigation into the activity of the enzyme in plasma and tissues under different conditions in man and experimental animals. The literature has been reviewed by Kay [1932] and by Robison [1932], and it is unnecessary to go into it in great detail here. Briefly, it may be said that in healthy young animals the activity of the plasma-phosphatase is higher than it is in the adult, but with the completion of rapid bone formation the value drops to the adult level. This is well illustrated by the observations of Stearns and Warweg [1933] with children. During the healing of rickets or other bone diseases the initially high plasma-enzyme activity tends to return to the normal for animals of that age and class. Abnormally high values may be observed in jaundice [Roberts, 1933] and possibly also after the ingestion of a high carbohydrate meal [Bodansky, 1934]. When proper precautions are taken it would seem that estimation of the plasmaphosphatase activity may serve in many mammals as a somewhat earlier indication of faulty Ca and P metabolism than do serum-Ca or inorganic P determinations, although high phosphatase values cannot be considered specific for any one disease. Clinically, estimations of tissue-phosphatase activity have a more limited value. Bone-phosphatase activity is high in rickets: it is diminished under prophylactic, and still more under excessive, treatment with vitamin D. Hypervitaminosis D also results in a decrease in the activity of the kidney-phosphatase. It has been shown that the tissue-phosphatase of fowls reacts in a manner similar to that of mammals [Hall and King, 1930-31; King and Hall, 1931]. Within the species, the individual variation of the plasma-phosphatase activity of normal adult mammals is not great [Kay, 1930; Auchinachie and Emslie, 1933]. From the values reported by Common [1934] it would appear that the normal range is wide in adult fowls. From the three values he gives for cockerels one might consider the range in these birds to be narrow, but the laying pullets vary from 6*9 to 27-7 Bodansky [1933] units, or approximately 0'23-0*92 Kay [1930] units'. These birds were considered to be strictly normal White Wyandotte pullets (personal communication) and the question naturally arises as to whether estimations of the plasma-(or serum-) phosphatase activity wiRl give any indication of faulty Ca and P metabolism in fowls, or whether there is normally such variation that phosphatase estimations have only a limited significance at the present time. 'Assuming one Kay unit to be equivalent to approximately 30 Bodansky units.

The work recorded in this paper forms part of the general investigation on nutrition in relation to disease recently outlined by Orr, Macleod, and Mackie(1).

RECENT work on the role of phosphatase has made it clear that the enzyme is closely concerned in the metabolism of calcium and phosphorus and in bone formation. Thus, it has been shown that an increased plasma-phosphatase content accompanies certain bone diseases in human beings [Kay, 1930], that a rise in value also occurs during the healing of fractures [McKeown and Ostergren, 1931], and that, during the healing of rickets in children, the phosphatase values are still abnormally high even after the serum-Ca and blood-inorganic P have returned to normal [Smith and Maizels, 1932]. Bodansky and Jaffe [1931] observed that certain dietary deficiencies were accompanied by changes in the serum-phosphatase of rats.In view of the marked changes which have been found in the serum-Ca levels of sheep suffering from experimentally produced "bent-leg" [Auchinachie and Fraser, 1932], it was considered desirable to determine whether the plasmaphosphatase of sheep fed on the same or similar diets would be affected in any way.EXPERIMENTAL. Blood samples were drawn at monthly intervals, and the plasma-phosphatase, serum-Ca, and blood-inorganic P values were determined. Plasma-phosphatase was estimated by the method of Kay [1930], serum-Ca by Tisdall's modification of the Kramer-Tisdall technique, and inorganic P by Havard and Reay's modification of Briggs's adaptation of the Bell-Doisy method. The sheep were also weighed at monthly intervals.Exp.

THE process of absorption of soluble substances from the intestine has generally been investigated by determining either the amount of substance which disappears in a given time after placing the solution in an isolated or T hiry Vella loop in the living animal, or its concentration in the absorbing fluid. On account of the obvious difficulties, both experimental and chemical, standing in the way of successful application of the latter method, when the blood of the portal vein is used, we have sought for some other means by which the behaviour of absorbed substances might be studied, and the present paper embodies the results.Diffusion is allowed to occur through the walls of isolated portions of intestine kept alive in a bath of oxygenated saline solution at body temperature. We shall show that under such conditions there is distinct evidence of selective absorption, and that this cannot be explained by known physico-chemical laws. Since there is no blood supply in the walls of the gut under these conditions and since, as Co ri, C ori and G olt z(1) have shown, soluble substances are absorbed from the peritoneal cavity in obedience to physico-chemical laws, it seems permissible to assume that the selective property is a function of the mucous membrane. We were led to the use of this method through the observation, made by one of us (H. E. M.) in association with Southgate(2), that the movements of isolated pieces of intestine are but little affected by marked changes in the chemical composition or the H-ion concentration of solutions placed in the lumen, whereas, as is well known, they are extremely sensitive to changes in the outer fluid. These workers also showed that destruction of the vitality of the lining epithelium, by preliminary treatment with weak sodium fluoride solution, increased the permeability so that the movements became immediately susceptible to the influence of solutions placed in the lumen.

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