organic framework is poor in calcium. The calcium content of the flesh and blood shows no variation and the brain but a slight variation from the normal. Following some experiments made by Sanford and Lusk at the Yale Medical School on new-born pigs, Wilson studied the influence of diet on the growth of young pigs. Three pigs were killed and analyzed at birth and three were reared on a skim-milk diet. To the diet of one pig, lactose was added; to that of the second, dextrose; and the third was given the skim milk without any added substance. The lactose-fed pig thrived best, while the pig fed on skim milk alone showed the least progress after sixteen days. The analyses showed that the pig fed on skim milk used 52 per cent of the calcium in the food for growth; the lactose-fed pig used 70 per cent; and the dextrose-fed pig 64 per cent. The calcium content of the bodies of the pigs at the end of the experiment was 8.29, 8.03, and 8.13 per cent, respectively. Calcium storage evidently depends on the development of the animal rather than on any specific influence of the milk constituents. Herter found striking retardations in the development of the skeleton of older pigs fed on skim milk for many months, but no evidence of rickets was seen. C W. Camerer, jr., finds that the calcium content of mothers' milk is barely sufficient to cover the needs of the nursing infant if the percentage composition of the five-months-old baby were the same as that of the new-born baby. The percentage of calcium in the newborn pigs above noted averages 9.4 per cent at birth and is 8.15 per cent at the end of two and one-half weeks' feeding. If the pigs fed on lactose and dextrose had contained 9.4 per cent calcium at the end of the two and one-half weeks' test, an almost complete calcium absorption would have taken place. Patterson states that when an animal is deprived of all inorganic salts in its food profound constitutional disturbances, resulting in death, are produced. The salts of the blood must not only be present in sufficient quantity to bring the osmotic pressure of the blood to a constant value, but they must also be present in certain definite ratios. Every living cell of the body must be washed by a fluid containing salts of certain monovalent and divalent metals in an unvarying ratio, otherwise a disturbance in the intracellular ionproteins (Loeb) or colloidal salts (Osborne) is produced. Bearing in mind this necessity for a constant ratio between the various salts of the blood, a number of interesting questions are raised by Patterson in regard to the probable effects of depriving an animal, com a Amer. J. Physiol., 1902, 8: 197. bJ. Exper. Med., 1898, 3:293. eZts. Biol., 1902, 43: 1. d Bio-Chem. J., 1908, 3:39. e Dynamics of Living Matter, New York, 1906. /J. Physiol., 1906, 34:84. pletely or partly, of one particular metal, say calcium. If the proper ratios are not maintained in the blood, then: (a) Is the excretion of calcium checked wholly or partially? During the progress of his research an article appeared by Goiteina which disposes of this question by showing that if a rabbit received less than 0.16 grams of calcium per kilo per day in its food, there was a steady loss of calcium from the body. Lehmann and others have shown that in starvation the calcium excreted exceeds the amount of this substance present in the drinking water taken. (b) Are the other salts of the body reduced pari passu by increased excretion? This would entail a considerable fall in the total molecular concentration of the blood, and as the living cells of the body and also the red corpuscles are extremely sensitive to osmotic changes this question may also be answered in the negative. (c) Is the deficiency in the food made good by certain tissues of the body giving up a portion of their calcium to the blood and so keeping the proper inorganic balance in this fluid? That this would be the most probable contingency may be inferred from a number of facts. Forster, who was the first to make observations on the effect of insuflicient calcium in the food, found that the muscles lost. 56 per cent of their calcium content, while the bones also showed a considerable diminution. Voitd found that on a calcium-poor diet the bones were more brittle, the skeleton showed a smaller percentage of dry weight than in the normal animal, and that the quantity of calcium in all organs of the body was more or less diminished. In the experiments in which rabbits were fed on oatmeal and maize meal, a diet which admittedly leads to calcium starvation, the ratio of the calcium of the blood to the total ash of the blood remained the same as that found in the normal animal. That is to say, the blood underwent no loss of calcium relative to the other salts in the time allotted to the experiment-a result which one might anticipate from the immense importance of the salt ratios of the blood. The ratio of calcium to the total mineral matter in the bones was, however, inconstant, and showed fairly wide fluctuations even in the normal animal. The bones can, without doubt, act as storehouses of calcium and possibly of magnesium. That they lose calcium when the animal is placed on a calcium-poor diet has been proved conclusively. Voit's results, however, tend to show that the bones can lose calcium relatively to the other salts, that is, by a selective autolysis. The experiments on his own body metabolism show that calcium can be readily stored during nitrogen retention. Arch. gesam. Physiol., 1906, 115:118. የ Maly's Jahres-Ber., 1873, 3:251. dZts. Biol., 1880, 16:55. More interesting, however, are the experiments involving rectal feeding, calcium being stored despite a continuous drainage of nitrogen from the body. In the latter case, as the protein absorbed from the food was insufficient, the muscles and glands must have diminished in bulk, and yet calcium was retained. This fact rather points to the bones as the place where calcium is stored. In the experiments on himself, and in those with rectal feeding, with a fixed diet the urinary calcium varied but slightly, and the variations, such as there were, ran parallel with the total amounts of urine excreted. This result is not remarkable if it is assumed that the kidney, in order to lighten its work against osmotic pressure, allows a fraction of each of the salts of the blood to escape into the urine. The greater the volume of the urine, therefore, the greater the amount of salts eliminated. The following theories have been published by Albu and Neuberga concerning the cause of rickets: 1. An insufficient amount of calcium in the food. 2. An inadequate absorption of the calcium salts of the food. 3. A disturbance of calcium retention in the bone-building tissues. 4. A disturbance of calcium absorption in bones themselves (Pfaundler), b 5. A connection between rickets and blood pressure based on the theory (Stöltz ner) that calcium metabolism is regulated by a secretion of the kidney. Similar theories as to the cause of osteomalacia were enumerated by the same author as follows: 1. A lack of calcium in the food. 2. A lack of calcium absorption from the food. 3. A decreased alkalinity of blood, following an excess of free acids in the blood which dissolve the calcium salts of the bone. 4. A perversion of metabolism, (Fehling), resulting from a diminished activity of the ovaries, which in time affects the calcium balance. 5. Hoennicke classes osteomalacia as a metabolism disease, the phosphorus metabolism being also affected. In pathological cases the results and opinions are many and diverse in regard to calcium elimination. For example, Beneke found increased calcium elimination in fever, while Senators obtained opposite results. In characteristic bone diseases, osteomalacia and rickets, the same state of affairs is found. Calcium and magnesium occur in the urine for the most part as phosphates. The quantity of earthy phosphates eliminated daily is a Mineralstoffwechsel, Berlin, 1906. b Münch. med. Wochenschr., 1903, 50: 1577. Arch. Gynaek., 1890 -1, 39: 171; 1894-5, 48: 472. e Berlin, klin. Wochenschr., 1904, 41: 1154. f Grundlinien der Pathologie des Stoffwechsels, Berlin, 1874. g Centrbl. med. Wissensch., 1877, 15: 357. somewhat more than 1 gram, and of this amount two-thirds is magnesium and one-third calcium phosphate. In acid urines the simple as well as the double acid earthy phosphates are found, and the solubility of the former (among which the calcium salt, CaHPO1, is especially insoluble) is particularly augmented by the presence of double acid alkali phosphates and sodium chlorid in the urine (Ott).a The quantity of alkaline earths in the urine depends upon the composition of the food. MAGNESIUM COMPOUNDS. The relative ratio of magnesium to calcium as eliminated by the body is 18 or 1: 9, and consists largely of magnesium phosphate, Mg,(PO1),. The amount of magnesium required by the body per day is 0.6 gram. As in the case of iron, though magnesium is necessary to health, but little magnesium is found in the child's food, namely, milk. The need of magnesium in the system has been studied by Bunge. The magnesium balances have been studied by Blauberg, Cronheim and Müller, Bertram, and Renvall, but are ́not considered as important as the calcium. Moreover, little study has been given to the elimination of magnesium under pathological conditions. с The elimination of phosphoric acid, calcium, and magnesium depends principally on the character of the food and the relative proportion of animal and vegetable food digested. A FEEDING EXPERIMENT WITH RABBITS. PLAN OF THE EXPERIMENT. In these experiments four female rabbits were used, the diet containing as little phosphorus as possible. To two of the rabbits organic phosphorus in the form of crude phytin was fed, and to the other two an equivalent amount of phosphorus in the form of sodium phosphates was given. It was intended to keep these four rabbits on their respective diets for three or four months, in order that they might become accustomed to the added phosphorus and, further, that it might be completely anabolized, and then to mate them and feed the young rabbits on the same kind of food and on phosphorus in the same respective combinations as that fed to the mother rabbits. When the young a Zts, physiol. Chem., 1886, 10 : 1. bZts. Biol., 1874, 40: 111, 295. C Ibid., 1900, 40: 1. dZts. diät, physik. Therapie, 1902-3, 6: 25, 92. Abs., Chem. Centrbl., 1879, 10 : 526. Skand. Arch. Physiol., 1904, 16: 94. rabbits had lived for several weeks on these diets, it was planned to kill them and to examine their bodies in minutest detail for various combinations of nitrogen and phosphorus. The same procedure was to be carried out in the case of the four female rabbits, and in addition, normal rabbits were to be examined as controls. Unfortunately, it proved impossible to obtain young rabbits under these abnormal conditions, that is, living in closely confined quarters (cages) and fed on an artificial diet. a The work was begun early in November, 1907, and concluded the middle of March, 1908. Complete nitrogen and phosphorus balances were determined during a period of nearly five months. Moreover, the inorganic phosphorus was estimated in the urine by the uranium acetate method throughout the entire time. In addition, during the last four weeks, calcium, magnesium, and ether-alcohol soluble phosphorus (lecithin) balances were included to make the study of the phosphorus metabolism more complete. At the end of the period the rabbits were chloroformed, and the bones, teeth, blood, livers, nerves (including the spinal cord) and brains were analyzed for nitrogen, total phosphoric acid, lecithinphosphoric acid, calcium, magnesium, water, ash, and ether extract. Two normal female rabbits were chloroformed and the same procedure followed as in the case of the rabbits artificially fed. In all cases post-mortem examinations were made and slides of the various tissues were prepared and histological changes noted. PREPARATION OF FOOD. The food consisted of carrots, gluten, a mixture of starch and sugar, olive oil, and salt solution. The above constituents seemed to furnish a well-rounded ration, supplying sufficient protein, fat, and carbohydrate for the needs of the body. The rabbits to which the inorganic phosphorus salts were fed received daily 5 cc of a standard salt mixture consisting of 450 grams of sugar, 4 grams of calcium chlorid, 15 grams of sodium chlorid, 30 grams of potassium chlorid, and 1 gram of magnesium sulphate, made up to a volume of 2,000 cc and containing 0.0492 gram of phosphoric acid, in the form of disodium hydrogen phosphate and sodium dihydrogen phosphate, per cubic centimeter. The rabbits to which the organic phosphorus was fed received daily 5 cc of a salt mixture made so as to supply an equivalent amount of the above mineral salts, allowance being made for the presence of calcium, magnesium, potassium, and phosphorus in the phytin. In this way an equal amount of calcium, magnesium, potassium, and a All the nitrogen work was done by the nitrogen laboratory, Mr. T. C. Trescot in charge. |