a smaller proportion of the absorbed nitrogen than did the rabbits fed inorganic phosphorus. With a few exceptions, the daily balances were positive. The rabbits fed organic phosphorus excreted less phosphorus through the kidneys than did those fed inorganic phosphorus, but they retained a larger proportion of the absorbed phosphorus. PRINCIPAL FEEDING PERIOD. The percentages of absorbed nitrogen retained in the case of the rabbits fed inorganic phosphorus show a wide variation, the average figure being practically the same as that for rabbit No. 1 fed organic phosphorus, rabbit No. 2 being excluded from the average. Accordingly, it is impossible to establish any effect produced on the nitrogen metabolism by the two forms of phosphorus fed. A larger proportion of the ingested phosphorus was eliminated by the kidneys in the cases of the rabbits fed inorganic phosphorus than where the rabbits were fed organic phosphorus. The proportion of absorbed phosphorus retained is greater for the rabbits fed on organic phosphorus. The daily balances were positive with the exception of rabbit No. 2, which died two weeks before the close of the experiment. The ether-alcohol-soluble phosphorus balances show that more phosphorus in this form was eliminated in the feces where phytin was fed than where inorganic phosphorus was fed. No ether-alcohol-soluble phosphorus was found in the urine in any case, and it is doubtful if any organic phosphorus is present in the urine of a normal rabbit. A smaller proportional amount of calcium was eliminated in the urine by the rabbits fed on inorganic phosphorus, but a larger proportiona! amount was retained in the body than in the cases of the rabbits fed on organic phosphorus. The same statement is true of magnesium. POST-MORTEM EXAMINATION. A large proportion of the phosphorus of the fresh intestines of rabbits is dissolved by water during the process of cleaning preparatory to analysis. The bones of rabbits fed on phosphorus for several months, either organic or inorganic, show a higher content of ether-soluble matter than do the bones of normal rabbits, and they form a larger percentage of the body weight than in the case of normal rabbits. The livers of the rabbits fed on organic phosphorus for several months show fatty degeneration as well as fatty infiltration. Of the livers of the inorganic phosphorus fed rabbits No. 4 shows both fatty degeneration and fatty infiltration; in the case of No. 3, only slight fatty infiltration is shown. The livers are enlarged and contain considerably more nitrogen and phosphoric acid than normal livers when calculated to a water and fat-free basis. In these experiments the degeneration and infiltration were most marked when organic phosphorus was ingested. The brains and nerves of the rabbits fed on organic phosphorus yield a larger percentage of ether-alcohol soluble phosphorus than those of normal rabbits, while the brains and nerves of those fed inorganic phosphorus show lower figures. There is also a larger percentage content of ether-soluble material in the brains and nerves. of the phosphorus-fed rabbits than is normal. The tendency of organic phosphorus, especially in the form of phytin, to produce fat was strikingly indicated in this experiment as in the work of Jordan, Hart, and Patten. The autopsies showed that all the phosphorus-fed rabbits were in an abnormal condition, the livers being especially affected, and the histological examination confirmed the autopsy findings. LIST OF TABLES. TABLE I. Nitrogen and phosphorus metabolism—preliminary period.... III. Nitrogen and phosphoric acid balances-principal period............. V. Ether-alcohol-soluble phosphoric acid balances-principal period... IX. Analysis of bones calculated to a fat- and water-free basis. Page. 34 37 38 39 42 44 47 49 50 51 |