IXTEKACTIOX OF PLASMA PHOSPHATE WITH THE PHOSPHOKUS COMPOUNDS 477 



corpuscle inorganic P, but in this way the rate of penetration would l)e 

 underestimated for the following reason : While active esters are forming 

 in the corpuscle a corresponding amount of non-active P ester decom- 

 poses, producing non-active inorganic P which dilutes the active in- 

 organic P present. (We denote as specific activity the activity per 

 mgm P). Therefore, to arrive to a proper figure for the rate of penetration 

 into the corpuscles we have to consider the total acid-soluble P present 

 in the corpuscles. As already mentioned, one part of the organic P of 

 the corpuscles reaches exchange equilibrium very rapidly while the other 

 becomes activated at a slow' rate ; and therefore the ratio of the specific 

 activities of the corpuscle inorganic P and total acid-soluble P does not 

 become = 1, but 1.8. This figure is only valid for the blood of the rabbit, 

 while a different figure will presumably be obtained for blood containing 

 appreciably more or less hydrolysable phosphorus. In the following 

 discussion the calculation of the penetration of HPO^, and of a mag- 

 nitude which we will call a penetration coefficient and denote as a will 

 be demonstrated (Comp. the list of symbols). 



CALCULATION OF THE COEFFICIENT OF PENETRATION 



The total activity of the plasma (ap) is equal to the product of the 

 specific activity (Sp) and the amount of phosphate (p) present in the 

 plasma. (Definition of the specific activity.) 



c denoting the total acid-soluble P of the corpuscles. During the ex- 

 change process a^ -fa,, remains constant, and therefore 



- Zl s = — Zl s, . 

 P 



At the beginning of the experiment the specific activity of the corpuscles 

 P was = and, accordingly, when denoting the specific activities at 

 the end of the experiment as S^ and S^, we arrive at a value of the spe- 

 cific activity of the plasma phosphateat the beginning of the experiment 



Sp = Sp+ySc- 



The rate of activation of Ihe corpuscle P being proporl ional to Sp — Sj- 

 we can write: 



