128 W. M. Wallace, W. B. Weil and A. Taylor 



regression line on the X axis defines the amount of phosphorus 

 present in 100 g. of calcium-free protein. This value should 

 reflect primarily the phosphorus content of muscle tissue. 

 From the statistical analysis of the calcium-phosphorus 

 relationship, a correlation coefficient of + 0-90 was derived. 

 Further, by the analysis of variance technique, it has been 

 determined that the regression curve is a straight line, des- 

 cribed by the equations calcium = 1'70 phosphorus— 51*1 

 and phosphorus = 0-48 calcium -f 43-6 when both are 

 expressed as m-mole/100 g. protein, and calcium = 2-19 

 phosphorus —2-04 and phosphorus = 0-37 calcium + 1*35 

 when both calcium and phosphorus are expressed as g./lOO g. 

 protein. The X intercept is between 30-3 and 43-6 m-mole 

 phosphorus/100 g. protein or between 0-93 and 1-35 g. phos- 

 phorus/100 g. protein. It is of interest that the calcium/ 

 phosphorus ratios of the four groups of rats studied by Light 

 and co-workers (1934) and the infants analysed by Widdowson 

 and Spray (1951) also lie on this regression line when their 

 values are calculated in this manner. This indicates that the 

 changes in phosphorus content of the various groups are 

 related to the changes in calcium and to the total amount of 

 protein present. The phosphorus concentration is constant in 

 the "soft tissue" (calcium-free protein), and the phosphorus 

 has a constant ratio to the calcium in the " skeleton " (calcium- 

 containing tissue). 



It is also apparent from the figure that the calcium to 

 protein ratio is highest in the low-protein, high-electrolyte- 

 fed animals and lowest in the high protein, low electrolyte 

 group. 



Discussion 



The present data, like the very similar data of Widdowson 

 and McCance (1957) and Stanier (1957), indicate no real 

 evidence for storage or depletion of protein with varying 

 intake. The basis for such a judgment is made by examination 

 of data calculated using either a kilogram of fat-free whole 

 body or 100 g. of fat-free dry solids as a standard of reference. 



