POODS — HUMAN NUTRITION. 463 



phosphates, hypophosphites, nucleic acid, phytin, and glycerophosphates. The 

 pigs were given a basal ration low in phosphorus, consisting of pearl hominy, 

 blood albumin, wheat gluten, and salt, to which were added the pliosphorus com- 

 pounds studied. In some experiments corn bran and small amounts of other 

 substances were added to the ration to relieve feeding difficulties. 



Detailed tabulated data are given regarding the gain in weight of the animals 

 in relation to food consumed; the weight and composition of various tissues and 

 organs of the slaughtered animals ; the development and strength of the bones ; 

 the chemical balance of mineral elements; the digestibility coefficients of the 

 l)roximate food constitutes; and the determination of nitrogen, ammonia, and 

 creatinin in the urine. 



In the discussion of the results of these experiments the authors bring out the 

 following facts: The results of one series of experiments indicated that "phos- 

 phorus from orthophosphates; hypophosphites, and yeast nucleic acid, when 

 added in the pure form to rations low in phosphorus but capable of maintaining 

 phosphorus equilibrium, may all be absorbed by swine, and may be retained in 

 considerable quantity for at least 10 days", and although not proved, it seems 

 possible that this retention may be permanent. Analyses of slaughtered animals 

 showed that the mineral constituents and ether extract of the blood, as well as 

 the relative proportions of the bone salts, varied consistently as affected by 

 the food. 



There was no evidence for the belief that phosphates and glycerophosphates 

 have different effects upon the gross composition, growth, and metabolism of 

 the animals. Glycerophosphates, however, are much better tolerated than are 

 phosphates. These experiments show that " with a low-phosphorus ration it 

 seems to be impossible to make up the deficiency of phosphorus by the addition 

 of readily soluble phosphates in the pure form." 



The phosphorus compounds studied are rated in the order of their decreasing 

 acceptability to swine when in amounts supplying equal quantities of phos- 

 phorus as follows: Glycerophosphates, phosphates, phytin, nucleic acid, and 

 hypophosphites. 



From difficulties encountered in feeding yeast nucleic acid, commercial phytin, 

 and the related compounds of wheat bran, the authors conclude that the isola- 

 tion of such compounds changes their therapeutic effects so that it is impossible 

 to determine from the experimental feeding of the pure compounds what is the 

 nutritive value of these substances as they occur naturally in foods. 



These experiments do not show that the organic phosphorus compounds 

 studied (nucleic acid, phytin, and glycerophosphates) are superior to the inor- 

 ganic compounds (orthophosphates and hypophosphites) as regards nutritive 

 value. "It would seem, therefore, that for purposes of growth, the usual diet 

 of animals must contain a sufficiently large proportion of organic to inorganic 

 phosphorus. In this relation, then the important consideration is simply one 

 of the total phosphorus of the ration, and any such supplemental phosphorus 

 as is to be added to the diet of the healthy, growing animal may be added as 

 inorganic phosphate. 



" It seems unlikely that, with grown or growing animals, any ration composed 

 from natural foods, and supplying the niti'ogen requirement, will fail to furnish 

 enough total phosphorus to maintain phosphorus equilibrium. That many 

 rations compounded from common foods are lacking in the amount of phos- 

 phorus essential to maximum retention and growth, however, is as certainly 

 true." . . . 



" The addition of comparatively small amounts of corn to rations compounded 

 from simple manufactured products of i^lant and animal origin may enhance the 

 nutritive value of such rations to an extent out of proportion to the amount of 



