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Eight wheat varieties which normally produce grain of different final percentage nitrogen content were grown under field and glasshouse conditions. The final percentage grain nitrogen of the field grown varieties ranked in the expected order; however, total nitrogen/grain, DNAIgrain, RNA/grain and non-protein nitrogen/grain during grain development differed between varieties. DNA/grain reached a maximum value in all varieties between 21 and 28 days post- anthesis, suggesting a longer period of cell division than previously reported. There was no apparent relationship between final percentage grain nitrogen and either DNA, total grain RNA or the concentration of grain amino acids during development. Heads from glasshouse grown wheat were detached at 8 days postanthesis and grown in liquid culture under conditions where the nitrogen concentration of the culture medium was varied. Fresh weight/grain, DNA/grain, RNA/grain and total grain nitrogen all increased with increasing nitrogen concentration in the culture medium, but grain dry weight remained constant at the different nitrogen concentrations. The changes in fresh weight/grain, DNA/grain and RNA/grain were not the same for all varieties. A possible relationship between total grain nitrogen and DNA/grain and RNA/grain during seed development exists for heads grown in culture for individual varieties. This apparent relationship for individual varieties cannot be used to explain intervarietal differences in total grain nitrogen because in some cases different varieties grown under identical culture conditions, although producing grain of equivalent total nitrogen, had widely differing levels of both DNA and RNA per grain.

The nitrogen increase which often accompanies the initial stages of vascular plant decomposition cannot be attributed solely to an increase in microbial protein. Evidence from litter bag experiments carried out in terrestrial, freshwater and estuarine environments indicates that as much as 30% of the nitrogen content of aged detritus may exist in the form of non-protein nitrogen compounds. Possible sources of these compounds include: (1) amino sugars such as glucosamine and chitin, (2) complexes such as phenol-protein, protein-lignin or protein-chitin, (3) complexes of inorganic clays and amino groups, and (4) nitrogen containing humic acids. Chitin, presumably originating from fungal cell walls was shown to constitute from 25 to 50% of the non-protein nitrogen contained in detritus which had decomposed under aerobic conditions. It is suggested that these non-protein nitrogen containing compounds, because of their resistance to chemical degradation, may not be easily digested and assimilated by many detritivores. This, in turn, may raise questions concerning the usefulness of detrital C/N ratios as food value indicators.

Urea as a Protein Supplement Edited by Michael H. Briggs. Pp. xi + 466. (Oxford, London and New York: Pergamon Press, 1967.) 140s.; $18.

Into a centrifuge tube, pipette 10 cc. of Folin's micro-tungstic acid solution. Make a reasonably deep wound in the finger to be assured of an adequately free and natural flow of blood, as squeezing appears to contaminate the sample. Using an accurate, capillary-bore pipette, draw up 0.1 cc. of blood. Carefully discharge the blood at the bottom of the centrifuge tube, and rinse the pipette with the clear supernatant solution; mix thoroughly. Allow to stand 2 or 3 minutes, and centrifuge. Decant the clear solution and apply a 4% correction for solution in the precipitate (or use a 5 cc. aliquot) and conduct a micro-Kjeldahl digestion. Collect the ammonia by distilling into 5 cc. of 0.1 N HCl. Fill the receiver tube containing the HCl up to the 25 cc. mark with distilled water, and add 5 cc. of Nessler's solution drop by drop while stirring. Add 5 cc. of the Nessler's solution to 25 cc. of the standard ammonium sulfate solution which should contain 0.1 mg. of nitrogen. Nesslerize the unknown and the standar...

During recent years, we have accumulated considerable data on the general question of nitrogen retention in the blood during the late toxemias of pregnancy; and, in view of the divergent opinions that prevail concerning the value of such determinations in the differential diagnosis and prognosis of these conditions, it seems that they should be recorded. Our investigations have led us to believe that blood chemical studies are at present of little or no practical assistance in the clinical management of these cases, and that the older methods of examination—urinalysis, blood pressure readings and ophthalmoscopy—yield the most valuable information concerning the patient's condition. Previous workers (Folin,1Caldwell and Lyle,2Killian and Sherwin,3de Wesselow4and others) have demonstrated that the substances studied (total non protein nitrogen, urea and uric acid) occur in normal concentrations in the blood during normal gestation. They have, moreover, pointed out that there

Tests for renal function fall into three general groups depending on: (1) The ability of the kidney to excrete from the circulation abnormal substances, such as dyes or drugs which are introduced into it; (2) analysis of the products of metabolism retained in the blood as a result of faulty eliminative powers of the kidney; (3) abnormalities in the physical and chemical properties of the urine. The phenolsulphonephthalein test is an excellent example of the first group. Rowntree and Geraghty 1 have found that the amount of this dye excreted in the urine after its intramuscular or intravenous injection varies almost in proportion to the degree of injury existing in the kidneys. This test is used so generally by clinical and experimental observers that its value in the study of the renal function can be accepted without further comment. Of substances studied in the blood of nephritics the

Ever since the time Prevost and Dumas, 1 who in 1823, first demonstrated an increase of the urea of the blood after extirpation of the kidneys in animals, the total non-protein nitrogen and the urea of the blood have been the subject of repeated investigations, and have been accorded considerable importance in the diagnosis and prognosis of Bright's disease. Owing, however, to the fact that the methods employed have been various and more or less subject to error, the results obtained have been conflicting. This may be readily seen when we find that the total non-protein nitrogen in the normal person is given as anywhere from 25 to 60 mg. per hundred c.c. of blood. The brilliant methods recently devised by Folin 2 render possible the accurate estimation of these substances in a small amount of blood, from 2 to 5 c.c. sufficing for all the analyses. The increase in

Last year one of us 1 in conjunction with Drs. Fitz, Folin and Denis compared the phenolsulphonephthalein excretion test in the urine with the non-protein nitrogen content of the blood in rabbits, in which an acute nephritis had been produced by the injection of uranium nitrate. It was found in this study that, although these two tests for renal function in a general way responded similarly in acute experimental nephritis in rabbits, there were certain variations. The excretion of the dye in the urine seemed to be a very fair indication of the rabbit's renal ability at the time of injection. On the other hand, the amount of retained non-protein nitrogen in the blood could be used as an indication of the renal efficiency at the moment only, provided the previous condition of the kidney was considered. No conclusions were drawn with regard to the prognostic value of these two

The nitrogen-containing crystalloids of blood have interested physiologists and clinicians for almost a century and in some respects the questions at issue are but little clearer to-day than in the time of Bright. Methods of research have changed and the data secured are more accurate, but it is remarkable in reviewing the literature that many of the conclusions of the later investigations are a simple rewording of the earlier. The facts have, however, been amplified and our knowledge made more complete without as yet any unaminity of opinion as to the significance of these facts. The amount of data at our disposal now is not inconsiderable and it may not be a useless task in the beginning to survey this field. Urea was first detected in the urine ( matiere savonneuse ), by Rouelle, Jr., in 1773, and in 1821 Prevost and Dumas observed an accumulation of urea in the blood of

Until the theories of nephritis are reduced to one and until that one has been conclusively proved to be correct, continued investigations, both clinical and experimental, seem to be demanded. These studies in nephritis deal on the one hand, with the accumulation or retention in the blood of the end-products of protein metabolism and glucose concentration in the blood, and on the other hand, with the functional capacity of the kidneys in so far as the latter may be determined by the elimination of phenolsulphonephthalein. In short, the purpose of this paper is to study : The relation of protein feeding to nitrogen retention in the blood. The relation of nitrogen retention to renal function. The relation of blood-sugar, blood-pressure, phenolsulphonephthalein elimination and nitrogen retention. So far as we can ascertain, there have been no studies covering all of these phases simultaneously and the possible

One of the important problems in connection with the study of nephritis is the determination of the ability of the kidneys to remove the metabolism products which normally find their way into the urine. Three different lines of investigation have been pursued in the study of this problem, namely, (a) urine analysis, the direct determination of urinary constituents, nitrogen, urea, chlorids, etc.,(b) blood analysis, the determination of similar products in the blood, particularly the so-called uncoagulable nitrogen and the urea, (c) the determination of the ability of the kidney to eliminate certain foreign substances, such as potassium iodid or dyes, indigo-carmin, rosanilin, phenolsulphonephthalein, etc. The first of these lines of investigation, urine analysis, has contributed very little, except in relation to the elimination of chlorids and water. To anyone familiar with the uncertainties and variations as well as the difficulties involved in nitrogen equilibrium experiments, this

The present study is based on the supposition that by the use of the recently acquired accurate methods for estimating the non-protein nitrogen of the blood, it might be possible to determine with greater precision than formerly the effects of sweat baths on the blood in nephritis. The sweat bath, advocated first for the removal of fluid from individuals with diseased kidneys, has more recently been extensively employed for the purpose of increasing the elimination of such solids as are normally excreted by the kidneys. Certain early observations seemed to afford a basis for such a procedure. It was found that in some nephritics, after sweating, a deposit was present on the skin which on analysis proved to be rich in urea. It was soon shown, however, that this phenomenon occurs only in agonal states or in conditions of extreme collapse when the permeability of the capillaries is quite abnormal