762 URINE. 



phoric acid. The total quantity of phosphoric acid varies and depends on 

 the character and the quantity of food. The average quantity of P2Os 

 is in round numbers 2.5 grams, with a variation of 1-5 grams per day. 

 A small part of the phosphoric acid of the urine originates from the 

 burning of organic compounds, such as nuclein, and phosphatides 

 within the organism; on exclusive feeding with substances rich in nuclein 

 or pseudonuclein the quantity of phosphates is essentially increased; 

 still it is undecided to what extent the excretion of phosphoric acid is 

 a measure of the absorption and decomposition of these bodies. 1 The 

 greater part originates from the phosphates of the food, and the quan- 

 tity of phosphoric acid eliminated is greater when the food is rich in 

 alkali phosphates in proportion to the quantity of lime and magnesium 

 phosphates. If the food contains much lime and magnesia, large quan- 

 tities of earthy phosphates are eliminated by the excrement; and even 

 though the food contains considerable amounts of phosphoric acid in these 

 cases, the quantity excreted by the urine is small. This is especially 

 true of herbivora, in which the kidneys are the chief organs for the 

 excretion of alkali phosphates. In man, according to EHRSTROM, the 

 content of lime in the food seems to play no important role, as in his exper- 

 iments about one-half of the phosphoric acid taken as CaHPC>4 was 

 absorbed, still the extent of phosphoric-acid excretion through the urine 

 depends in man not only upon the total quantity of phosphoric acid in 

 the food, but also upon the relative amounts of the alkaline earths and the 

 alkali salts of the food. In carnivora, in which phosphate injected sub- 

 cutaneously is eliminated by the intestine (BERGMANN), the urine is 

 habitually poor in phosphates. 2 



As the extent of the elimination of phosphoric acid is mostly dependent 

 upon the character of the food and the absorption of the phosphates 

 in the intestine, it is apparent that the relation between the nitrogen and 

 phosphoric-acid excretion cannot run parallel. This is in fact so, and, 

 according to EHRSTROM, the organism has the power of accumulating 

 large quantities of phosphorus for a relatively long time independent of 

 the condition of the nitrogen balance. With a certain regular food the 

 relation between nitrogen and phosphoric acid in the urine can be kept 

 almost constant. Thus on feeding with an exclusive meat diet, as 

 observed by Vorr 3 in dogs, when the nitrogen and phosphoric acid 



1 gee A. Gumlich, Zeitschr. f. physiol. Chem., 18; Roos, ibid., 21; Weintraud, 

 Arch. f. (Anat. u.) Physiol., 1895; Milroy and Malcolm, Journ. of Physiol., 23; Roh- 

 mann and Steinitz, Pfliiger's Arch., 72; Loewi, Arch. f. exp. Path. u. Pharm., 44 and 45. 



2 Ehrstrom, Skand. Arch. f. Physiol., 14; Bergmann, Arch. f. exp. Path. u. Pharm., 

 47. 



3 Physiologie des allgemeinen Stoffwechsels und der Ernahrung in L. Hermann's 

 Handbuch, 6, Thul. 1, 79. 



